BIOL 252 MWF (12-12
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Date Created: 05/14/15
BIOL 252 Anatomy and Physiology MWF 121250 82014 How and why do we get sick and die Fathers of Anatomy Hippocrates 400 BCE Father of Western Medicine Sought natural causes for disease Aristotle 300 BCE Taught students to seek out information and observe on their own Galen 100 AD Proponent of 4 humors as source of disease accepted as doctrine for centuries ViVisectionist performed animal dissections Avicenna amp Maimonides Studied deviations from Galenic structure Andreas Vesalius 1500s Skeptic and showed aws of Galen Started to draw human anatomy accurately 82514 Nervous System Neuroglia of CNS 1 astrocytes nutrient and ion reservoirs connect neurons to blood vessels transports nutrients and waste between blood and neural support cells 2 oligodendrocytes produce myelin sheath 3 ependymal secretes cerebrospinal uid 4 microglia phagocytosis of debris involved in growth and regeneration of CNS cells Neuroglia of PNS 1 Schwann cells produce myelin sheath 2 Satellite cells like astrocytes and microglia of CNS Myelin Sheath Myelination occurs primarily in axons much less near dendrites and soma Why are parents told to feed babies whole milk for at least 2 years 0 No myelination at birth 0 Myelination progresses rapidly through adolescence at least I Requires lots of fat intake in first few years Multiple Sclerosis 0 Lose oligodendrocytes 0 Adult loses myelin sheath Tay Sach s 0 Inclusion of proteins in myelin corrupts it and renders useless Structure of Neurons Axon hillock signal converted to electrical impulse Resting Membrane Potential RMP 0 Inside large anions that are stuck inside cell too large to escape through channels 0 Na leak into cell across gradient 145 mEqL outside 12 mEqL inside 0 K ions leak out of cell constantly 150 mEqL inside 4 mEqL outside I Moves down chemical concentration gradient 0 Resting potential of 70mV inside 0 SodiumPotassium Pump I 3 Na pushed out of cell for 2 K into cell uses 1 ATP per cycle I Maintains gradient against leakage I Builds up an electrical gradient more negative in cell Local Potential 0 Na allowed to diffuse quickly into cell through ligandgated channel 0 In ux of ions depolarizes soma locally to 55 mV I Triggers action potential upon reaching threshold voltage Action Potential 0 Full depolarization of neuron occurs 0 Voltagegated Na channels open to allow Na to enter neuron quickly I Rapid increase more positive in cell potential At 35 mV Na channels shut and voltagegated K channels pump K out of cell Dumping of K ions repolarizes membrane H yperpolarization cell potential overshoots 70 mV before reequilibrating NaK pump restores ions to prior concentrations Refractory membrane after action potential membrane unable to be triggered OOOOO again for a short time until RMP is established signal can only go in 1 direction 0 1 ms for action potential refractory period lasts up to 50 ms I Requires NaK ATPase pump to restore chemical gradient Myelination and Action Potentials Allows action potentials normally 120 ms to speed up Action potential not triggered in myelinated regions Nodes of Ranvier unmyelinated region where action potential can be triggered 0 Acts like repeater towers boosts signal so it can be propagated with fewer action potentials O Ions don t have to move across entire length Requires fewer ions and less ATP Cost extra energy for support cells more space required Warmer temperatures higher activity of proteins and ion movement Local Potentials In dendrites and soma due to ligandgated ion channels Ligands neurotransmitters Bind to ligand gated Na channel I depolarization locally I accumulation breaches threshold I action potential Local vs Action Potentials O Ligand gated channels voltage gated channels 0 Depolarizing or hyperpolarizing always depolarization then repolarization O Proportional to signal strength a11ornone O Reversible prior to threshold irreversible 39 Decisionmaking 0 Local selfpropagating Synapses Chemical communication between neurons Synaptic knob of presynaptic neuron I dendrite of postsynaptic neuron Action potential I Caz vesicles open I release of neurotransmitter into synaptic space I diffuse amp bind ligandgated ion channels I trigger local potential 82714 Complex Actions Emerge from Simple Components One neuron can have 10000s of synaptic connections Synapse Synaptic clefts are 15 nm in width Can either depolarize excite or hyperpolarize inhibit postsynaptic neuron 0 Add positive ions to inside of cell excite membrane Presynaptic Inhibition O Presynaptic neurons can only in uence postsynaptic neuron I Many thousands of presynaptic connections I if the signals are counteractive then no action taken 39 Signals have to be in agreement to trigger event in postsynaptic neuron I Input from multiple synapses is summed at axon hillock where decision to fire or not is made based on total buildup of charge 0 Without inhibition it would not be possible to control somatic motor neurons O Inhibitory neuron releases neurotransmitter that hyperpolarizes synaptic knob of presynaptic neuron I prevents release of neurotransmitters to postsynaptic neuron I Allows for randomunplanned action potentials from acting I If many signals arrive repeatedly I overcome hyperpolarization and cause neuron to fire actives release of neurotransmitter into postsynaptic neuron 0 Can have synaptic knobs connected at neurosoma not just at dendrites Summation of Stimuli 0 Temporal summation 1 presynaptic neuron stimulates intenselyrepeatedly in short period of time I triggers postsynaptic neuron excitement 0 Spatial summation multiple presynaptic neurons stimulate trigger zone I overcome threshold and trigger action potential Neural Circuits and Integration Diverging 0 Single input causes action potential in many postsynaptic neurons 0 In skeletal motor control Converging 0 Multiple presynaptic neurons lead to excitation of multiple postsynaptic neurons 0 Sensory neurons Reverberating 0 Input from a single presynaptic neuron produces responses in postsynaptic neurons I One neuron down circuit excites initial neuron to continue firing I Positive feedback loop Inhibitory synapse at some point to stop Parallel After Discharge 0 One action potential triggers many postsynaptic neurons to fire in diverging parallel paths that eventually converge I Some paths are slower than others triggers prolonged excitatory response over time from 1 initial action potential The Spinal Cord Grey matter center surrounded by White matter myelinated axons Contains synapses of sensory and motor neurons With interneurons and CNS Nerve Fibers amp Nerves 0 Nerve bundle of axons bundled in fascicles made of perineariam I Also contains blood vessels Schwann cells and satellite cells 0 Ganglia PNS and Nuclei CNS I Present in dorsalposterior nerves I Contain neurosoma 82914 Autonomic Nervous System PNS I motor amp sensory I Visceral motor Sympathetic amp parasympathetic amp somatic motor Sympathetic fight or ight Parasympathetic rest and digest Spinal Nerves Rootlets combine to form spinal nerves 0 Dorsal roots carry sensory neurons cell bodies contained in dorsal ganglia I Filter and organize sensory input before it gets to CNS 0 Ventral roots caries motor neurons cell bodies in ventral horn of spinal cord Re exes Re ex arcs are behaviors that protect tissues in the body Fast stereotyped involuntary actions in response to stimulation of a sense receptor Skeletal re exes sensory neuron stretch receptor I dorsal ganglion I dorsal horn I motor neurons stimulate activation of 1 muscle inhibits antagonist Stretch Re ex 0 Primarily protects connective tissues that don t heal well tendons ligaments 0 Have minimal number of synapses 2 sets eliminate slowest step in signal Flexor amp Crossed Extension Re exes 0 Signal to dorsal horn I move foot up same as stretch path 2 syanpses 0 More complex 2nd signal additional synapse I Extension of muscles in opposite leg amp lean I keep you standing up I Signal decussates to opposite dorsal horn Strong selection for and retention of mechanisms Autonomic Re ex Arcs O Visceral muscle and glands slower than skeletal re exes 0 Stretch receptors in carotid artery amp aorta detect increased blood pressure I medulla oblongata I vagus nerve I signal to heart pacemaker to decrease heartbeat 0 Sympathetic motor myelinated preganglionic fibers I synapses in autonomic ganglia spinal cord I unmyelinated postganglionic nerve fiber I effector I Allows for prolonged response from single stimulus I Acetylcholine in preganglionic synapse I Norepinephrine released to effector by postganglionic system 0 Parasympathetic motor myelinated nerves all the way to ganglion adjacent to organ I bathes target tissues in neurotransmitter I Acetylcholine in preganglionic synapse and released to effector Autonomic tone 0 Parasympathetic and sympathetic systems act in concert to maintain normalcy 0 Ex pupil I Stimulate dilation and contraction simultaneously to maintain pupil size 0 Ex vasoconstriction I signal only sent by sympathetic nervous system l Without signal automatically relax 9314 How do simple neural mechanisms produce cognition Barriers Maters and Maters 3 meninges surround brain to cushion it from hitting skull Provide blood and nutrients to brain Bloodbrain barrier amp BloodCSF barrier protects brain from harmful compounds in blood Arachnoid mater creates loose exible bubble full of cerebrospinal uid around brain 0 Only connected to skull in a few places allows movement to prevent trauma White matter lots of glial cells myelination interior of brain Gray matter somas dendrites and synapses brain surface pockets in center of brain Regions of Brain Cerebrum O Gyri and sulci allow more surface area for more gray matter 0 Corpus collosum white matter bridge connecting two hemispheres Cerebellum 0 Contains folia and sulci that increase surface area 0 Vermes connects two hemispheres of cerebellum O 10 of brain mass 50 of neurons in brain 0 Motor coordination compares intention of action with sensory information to adjust movements for fine coordination Brainstem O Oldest part of brain evolutionarily 0 Full of tracts of white matter and ganglia or gray matter 0 Medulla oblongata decussation occurs here 0 Pons carries signals through to brainstem I Nuclei control ANS movements Midbrain O Retina develops from this part of brain 0 Coordinates vision with head movements filters pain 0 Substantia nigra produces dopamine to inhibit basal ganglia Diencephalon 0 Contains thalami process sensory info relay to cerebrum involved in memory emotion motor control 0 Hypothalamus control center for autonomic regulation instinct Reticular Formation 0 Web of gray matter in white matter of midbrain and brainstem 0 Cardiovascular tone consciousness sensory habituation pain etc Limbic System O Inferior cerebrum of each hemisphere amygdala basal nuclei hippocampus O Singuloid cortex and amygdala may be correlated With controlling reason vs emotion issue Cerebral Tracts 0 Projection Tracts I Bundles of axons that carry info tofrom cerebrum to rest of body 0 Commissural Tracts I Carry info from one side to other parts of the cerebrum Neocortex cerebral cortex 0 Thin but makes up much of brain 0 Where most of integrative synapses occur only 6 soma deep 0 Large pyramidal cells project to other parts of brain and spinal cord 0 Small pyramidal cells most of processing and integration I Stellate cells connect the pyramidal cells Cerebral Cortex 0 Association areas near primary cortex 0 Somatosensory association area information compared with memory intent motor functionality 0 Prefrontal cortex rapid decisionmaking integrates signals from throughout neocortex 0 Associated With subtleties of personality decisionmaking O Cerebral Lateralization regions tend to specialize in certain tasks I Left categorical process numbers language structured thought I Right imagination insight artistic ability 0 Concussion I Trauma all over the brain signals from pyramidal cells from angular momentum I Axon stretching damage to plasma membrane inability to hold membrane potential I Impairs ability to send signals 9514 General Senses Touch pressure temperature pain stretching etc Labeled line code brain can differentiate Which modality is being received by Which nerve is stimulated Postcentral gyrus part of cerebral cortex for receiving sensory information from body 0 Cortical magnification Areas with more refined feeling amp refined movement get larger area I Based on density of sense receptors in body Precentral gyrus cerebral cortex area responsible for creating motor movements 0 Similar magnification based on how fine motor movement is in area Somatoreceptors Unencapsulated 0 Free nerve endings dendrites can have different triggers based on what they detect I Located mostly everywhere except brain I Temperature tissue damage pain etc 0 Tactile disc nerve ending with starshaped tactile cell above it epidermis I Responds to light touch edges and type of movement direction 0 Hair Receptors wrapped around hairs very sensitive Encapsulated O Tactile corpuscle sensitive to very light touch in dermal papillae End bulb same as above in mucous membranes Bulbous corpuscles heavy pressure deeper in tissue amp joints Lamellar corpuscle same as above Muscle spindle amp tendon organ proprioception stretch in muscletendon OOOO Pressure deforms capsule I increases membrane potential until depolarization 0 2nd action potential fired when sensation ends Receptive Fields Area a single neuron can detect sensory info More neurons in smaller area ability to distinguish location better smaller field for each neuron Speed of sensory neurons 0 Phasic fire quickly and only for a short time 0 Tonic respond slowly respond continuously as sensation continues Projection Pathway Pain bypasses reticular formation directly to thalamus spinal gating O Forebrain can impose inhibition between 1st order sensory neuron and 2rld order 0 In midbrain inhibitory signal sent to synapse receiving pain signal in pre and postsynaptic inhibition by endorphins endogenous opioids enkephalins Referred Pain 0 Pain coming from one area but brain thinks it s coming from elsewhere I Brain takes mostlikely source of pain info Carried along same 2rld order nerve fiber 0 Sphenopalatin ganglioneuralgia brain freeze 39 Overstimulate cranial nerve V by cold temperature I perhaps referred pain Special Senses Why is taste less acute than olfaction O Smell has to detect chemicals at much lower densities than taste I Stronger selection for smell more important for survival 0 Spinal cord amp medulla have changes little in vertebrates different sections of brain specialized in processing senses O Humans lack area in nose capable of detecting large molecules produced by others of species I pheromones l We re not sure how we detect or manipulate others With chemicals I Forebrain extended chemical processing to other senses 982014 Gustation Bitter alkaloids tend to be dangerous chemicals Umami amino acids Gustation Chemoreceptors 0 Around 10000 taste cells 0 Some foods trigger nociceptors sense of pain thermoreceptors heatcool 0 Projection of taste hairs in taste pore to taste cells transmit signal to neurons Olfaction Chemoreceptors O 10 million cells 0 Odor molecules must cross hydrophilic barrier of mucus to contact olfactory hairs 0 Signal passes to glomeruli that are specialized in specific molecules Olfactory Projection 0 Signal reaches forebrain first I Only sense that is processed in forebrain first Audition most demanding physical challenge for transduction relatively unusual in invertebrates largely vertebrate phenomenon in a uid hearing requires detecting vibrations in air most energy lost in transferring signal to liquid medium Transduction 0 Every 6 dB 1 order of magnitude of energy 0 Above 120 dB feel pain 0 Outer Ear I Focuses and concentrates sound onto tympanic membrane 0 Middle Ear I Eustachian tube equalizes pressure in ear connects With nasal cavity Can get infectionbackup I prevents equalization I Stapes incus and malleus transmit vibration of membrane into oval window concentrates air vibrations into liquid vibrations Reduce area of vibrations I Mechanism prevents sound transduction When making sound to prevent destruction of ear 0 Inner Ear I Semicircular canals provide sense of momentum I Cochlear nerve transmits more info than vestibular nerve I Cochlea Scala vestibuli perilymph cochlear duct endolymph scala tympani perilymph Auditory Projection Hair cells embedded in basilar membrane receive signal Vibrations travel through scala to transmit signal to basilar membrane causes hair cells to vibrate Outer hair cells form vshapes to tune mechanism increase accuracy of response 0 Can tighten up to anchor tectorial membrane with tips near areas of vibration I allows ear to focus vibrations in particular locations on cochlea isolate specific frequencypitch Inner hair cells transduce signal to brain 0 Tip link tops of cells connected so they respond in kind 0 As cells bend mechanicallygated channels open to release K into cells I action potential High frequency proximal cells low frequency distal cells Equilibrium 0 Vestibule organs saccule vertical mvmt amp uticle horizontal mvmt I Saccule contains macula patch of epithelium embedded in otolithic membrane filled with Ca2 derivatives make it heavy Membrane moves in response to movement or gravity I causes hair cells to bend 0 Semicircular ducts I Run in 3 different planes I Detect movement of uid through cupola gelatinous membrane over hair cells 0 Judge signals from both ears to determine What movement is occurring 0 Vestibular Projection 91014 Vision Receptor Cells all receptor cells have hair cells With cilia eyes are different I rodscones are very specialized evolved hair cells Vision amp the eye is flawed can lead to high youth mortality defective vision is extremely common Optic Components cornea mostly collagen epithelial cells maintain water balance amp hear cornea to keep it clear amp uniform in thickness aqueous humor fills anterior and posterior chambers provides support to shape cornea iris pigmented muscle that controls light that enters lens lens suspended by ligaments focuses light on retina ciliary body muscular structure that tensions ligaments to change lens shape vitreous body hyaloid canal blood vessel in fetal development to lens becomes adjustable chamber in eye allows change in vitreous body Refraction most refraction occurs at aircomea boundary 138 I aqueous humor 133 I lens 140 I vitreous body 133 little refraction after light his cornea bc of large difference in index of refraction lead to bending of light spherical aberration fuzziness at edges because of significant refraction Neural Components optic nerve retina optic disc fovea centralis emmetropia eye is relaxed pupil dilated lens is thin when focus is gt 6 m away 0 light runs parallel into eye near eld vision 0 convergence eye point inward toward object so light strikes middle of eye 0 papillary mi0sis iris contracts to shrink pupil cuts down blurriness nonparallel light movement amp spherical aberration 0 lens accommodation lens thickens to refract light more Flawed Vision emmetropia all light focused on fovea centralis on retina hyperopia farsightedness light focuses behind retina myopia nearsightedness light focuses before retina presbyopia minimum focal distance moves further away 0 lens becomes less adjustable Retina fovea centralis has high density of cones to provide high resolution images 0 Sits in macala latea at center of eye Derived from CNS tissue during development Light passes through ganglion cells then bipolar cells and photoreceptors buried in pigment epithelium 0 Very inefficient way to see Optic disc blind spot on retina where nerves and blood vessels pass into eye 0 Eye moves very quickly to keep anything important from getting lost in optic disc Rods and Cones Rods Rods measure amplitude of light sensitive to low amounts of light sc0t0pic Get bleached in high intensity light Pigment rhodopsin Low resolution because many rods stimulate l bipolar cell convergent circuit 39 Can see very low levels of light but low resolution Cells are larger than cones Rods inhibit bipolar cells with glutamate in absence of light 0000 DO Cones O Respond to specific frequencies of light ph0t0pic Vision Pigment forms of photopsin change conformation when stimulated by photons 0 Signal from each cone transmitted to its own ganglion cell no real neural O convergence I Also inhibit bipolar cells with glutamate in absence of light I Produce much greater resolution but less sensitivity 0 S cones short wave peak in violet O M cones peak in bluegreen O L cones peak in green extends to red Stereopsis and Retina O Stereoscopic vision gives brain info about location of object I Light strikes medial to fovea distant I Light strikes fovea Fixation point I Light strikes lateral to fovea near field 0 Requires fine motor control of eye movement Visual Projection Pathway O In motor and somatosensory system decussation in medulla 0 Hemidecussation only half of signal crosses over I Right brain gets info from right side of each eye Nobel Prize of 1981 Medicine 0 Coordination of eye movement END OF EXAM 1 91514 Endocrine System Endocrine vs Nervous Chemical communication through bloodstream vs neurons Nervous system 0 Fast signaling onset and offset Endocrine system 0 Slower longerterm signaling 0 Able to enact signaling efficiently only small concentrations required 0 Can be very specific or very nonspecific 4 Forms of Signaling Aatocrine cell targets itself Signaling across gap junctions between adjacent cells Paracrine local signaling across gaps between cells Endocrine cell targets distant cell through bloodstream Exocrine vs Endocrine Endocrine releases substances into bloodstream through capillary system Exocrine invagination releases chemicals into nearby tissues through ducts Both derived from epithelium Individual cells can act as exocrine glands or endocrine glands O Goblet cells histaminereleasing cells 0 Liver cells can do both 3 Types of Hormones Steroids lipid cholesterol derivatives lots of interconversion of structures 0 Produced in gonads and adrenal glands Monoamines amino acidderived retain NHR group relatively small molecules 0 Communicate in bloodstream and in neuronal synapses as neurotransmitters I Melatonin dopamine norepinephrine Peptides derived from amino acid chains wide range of sizes often large and complex 0 Mostly specialized for specific processes I Erythropoietin EPO leutenizing hormone LH follicle stimulating hormone FSH thyroid stimulating hormone TSH Why do hydrophobic hormones need hydrophilic transport proteins 0 Need a hydrophilic carrier protein often produced in liver to carry some peptides and steroids through blood 0 Carriers reduce rate of filtration and breakdown of these hormones in body I Allow the hormones to persist Signal Ampli cation Hormone I receptor I cAMP and protein kinases I secondary enzymes I metabolic product Hormones trigger cellular processes through gene expression that work internally on cell or for distribution around the body Target cells and Receptors 0 Peptide Hormones I Too large to cross cell membrane mostly hydrophilic I Bind hormone receptor coupled with membrane enzyme I Triggers activation of CAMP or are carried inside cell by receptor I Enzymes activated 0 Steroid hormones I Hydrophobic able to diffuse across membrane and into cell I Tend to target nucleus of target cells I activate transcriptiontranslation 0 UpRegulation I Target hormones lead to greater expression of receptor proteins 0 Increases cell sensitivity to hormonal signal by increasing number of receptors 0 DownRegulation I Target cell produces fewer receptor proteinsbreak down receptors I Desensitizes cell response to hormone 0 Occurs often with hormone therapies Control of Hormones Because of persistence of hormones need careful regulation Excretion transport and clearance are regulated by negative feedback 0 Target cells produce hormone 2 to turn off hormone lproduction once they receive signal from hormone 1 Major Endocrine Organs Pineal Hypothalamus Pituitary Thyroid Parathyroid Thymus Adrenals Pancreas Gonads 91714 Endocrine Lecture 2 Persistent signal over period of time Need immediate response that persists over a period of time Hydrophobic hormones need transport proteins to carry them in blood Peptides and monoamines need transport protein through membrane or trigger 2nd signaling protein Hypothalamus amp Pituitary pineal gland converts serotonin I melatonin While we sleep reverse When we wake up 0 too little melatonin sleep deprived too much irritable seasonal affective Hypothalamus O descending fibers regulate heart rate blood pressure GI tract activity body thermostat thirst amp hunger internal clock emotional arousal etc 0 strong in uence on pituitary o Hormones I Excitatory or inhibitory for other hormones esp in anterior pituitary Pituitary Gland 0 Anterior Pituitary I Hypophyseal portal system hormones produced by hypothalamus transferred to anterior pituitary to regulate secretion through series of capillary beds I Endocrine gland releases hormones in response to other hormones 0 Posterior Pituitary I Connected to hypothalamus by nerves stores hormones produced in hypothalamus I Essentially an extension of hypothalamus I Trigger quick release of large amounts hormones little latent period for situations When you can t wait for rampingup of hormone production HypothalamicPituitarytarget Axes Hypothalamus triggers more specialized glands to release hormones at a higher rate I creates faster overall responses Amplifies signal at each step hypothalamus I anteriorposterior pituitary I gland PRH prolactin releasing hormone amp prolactin inhibiting hormone GnRH I LH FSH I targets testis and ovaries 0 LH amp FSH spike at ovulation estrogen spikes prior to ovulation O Progesterone is high from ovulation until menstruation ADH antidiuretic hormone decreases water loss by increasing reabsorption of water by kidneys triggers thirst TRH Thyroid Releasing hormone I TSH thyroid stimulating hormone anterior pituitary I growth of thyroid amp TH thyroid hormone O Increases cellular metabolic rate inhibits release of TSH and some TRH negative feedback 0 If negative feedback too strong hypothyroidism I Coldness fatigue weight gain poor appetite 0 Also hyperthyroidism low Iodine levels HGRH HGIH HGH somotropin I targets liver 0 High levels during childhood level declines With age 0 Short halflife in body 0 In liver triggers production of insulinlike growth factors IGFs I Effects like HGH but longer halflife 0 In milk rBSTB GH may act like HGH in human body CRH I ACTH I cortisol Most hormones involved in complex feedback loops With 23 glands and Widespread effects Posterior Pituitary ADH increases water retention by kidneys triggers thirst Oxytocin labor contractions milk release sexual affection matechild bonding Exceptions to signal amplification I need fast onset of effects 91914 Stress Reason for using endocrine vs nervous system 0 Less energy more efficient pathway 0 Tradeoff speed of onset and dissipation of signal What is stress 0 Response to something we can t control in our environment I Temperature blood loss attack loss of homeostasis 0 Physical infectious agent temperature dehydration etc 0 Mental 0 Change in autonomic tone to favor sympathetic nervous system Parasympathetic v Sympathetic O Somatic myelinated from ventral horn I synapse Ach I skeletal muscle 0 Sympathetic short myelinated I ganglion ACh I longer unmyelinated to organ Norepinephrine 0 Parasympathetic long myelinated nerve I synapse ACh I ganglion close to target organ ACh 0 Autonomic Varicosities I Sympatheticparasympathetic system don t have clean synapses with cells I Varicosities bulges With synaptic vesicles that release neurotransmitters onto surrounding cells less targeted than motor Parasympathetic Innervation O Arises in brain and sacral spinal region spinal nerves 3 7 9 10 O Relatively little convergence of these nerves 1 preganglionic I 5 postganglionic I Relatively good targeting Sympathetic Innervation 0 Lots of convergence 1 preganglionic I 1020 postganglionic I Faster in uence on tissues because there are more signals I Fewer synapses speeds up signals General Adaptation Syndrome 0 Alarm I A stressor perturbs homeostasis shock I Body reacts to stressor countershock I Adrenal Medullas amp Alarm I Ganglion of sympathetic nervous system 0 Fearaggression signals in amygdala communicate With hypothalamus that uses sympathetic fibers to excite adrenal medulla to release hormones O Medullas excrete adrenalines epinephrine and norepinephrine through chromafin cells weird no dendrites or axons O Assists With conversion of glycogen to glucose 0 Preganglionic fibers use Acetylcholine instead of norepinephrine to excite medullas 0 Resistance I In longerterm response I Adrenal Cortices I Cortisol release stimulates breakdown of lipids and proteins into energy sources starts gluconeogenesis 0 Hypothalamus releases CRH to cause pituitary to release ACTH adrenocorticotropic hormone to cause adrenal cortex to release cortisol 0 Promotes in ammation and damage repair 0 ACTH inhibits release of CRH by hypothalamus I Cortisol inhibits release of ACTH and CRH 0 Exhaustion I Immune system suppressed 92214 Endocrine System Hormonal birth control has revolutionized industrial society Most animals males competing females are choosy sex HypothalamicPituitaryOvarian Axis Regulated by positive amp negative feedback loops Maturing ovarian follicle ovum surrounding tissue secretes estradiol Estradiol triggers release of Gonadotropinreleasing hormone GnRH from hypothalamus Anterior pituitary releases Leutenizing Hormone LH and Follicle Stimulating hormone FSH Maturing of dominant oocyte ovum becomes more F SH sensitive While other follicles become less sensitive High levels of estradiol downregulate GnRH Testosterone Aromatase amp Estrogen Testosterone O Secreted by gonads 0 Remains high in males 0 Converted by aromatase into estradiol in females Effects I Excites muscle and bone tissue growth promotes aggression I Suppresses immune system strains heart tissue and blood vessels 0 Levels reduced over time because of poisonous effects 0 We treat decline in testosterone as a disease I it s just old age 0 FDA wants to restrict offlabel use of testosterone I Greatly increase risk of heart attack stroke etc As GnRH is inhibited less FSH secreted by anterior pituitary but more LH is secreted in middle of follicular phase 0 Most follicles degenerate except for the 1 that upregulated sensitivity Near day 14 estradiol then LH and F SH cause rupture of follicle amp release of mature egg Hormones during Pregnancy Human chorionic gonadotropin enormous spike after conception O Stimulates growth of corpus luteum I placenta Placenta and corpus luteum release high levels of estradiol and progesterone inhibit GnRH F SH LH no ovulation Medications simulate pregnancy to prevent ovulation on college campuses there have been ovulatory and nonovulatory cohorts of students due to birth control 0 allow for lots of studies Ovulation and male attractiveness 0 women in nonbirth control group amp likely ovulating I prefer males with higher testosterone levels Ovulation and female attractiveness 0 find female faces less attractive right before ovulation than right after ovulation Tshirt Experiments 0 Men wear shirts to infuse them with scent women select attractiveness by smell 0 women more likely to choose males with distinct immune genes from their own 0 men can detect whether woman is ovulating or not just from smell I more apparently attractive O secretions of apocrine glands include chemicals that advertise hormonal conditions pheromones Major Histocompatibility Complex Highlyvariable regions of vertebrate genome critical to antibodyresponse and cellbased immune response Code for variability allow T cells to recognize self vs nonself Antibodies can bind to exogenous threats more variable recognize more external substances faster immune response healthier Swiss Study Women not on hormonal birth control prefer men with more different MHC genes 0 When looking for a mate women look for better genetic match Women on hormonal birth control preferred men with MHC genes that were more similar 0 Prefer company of kin when they are pregnant Implications mate choices made when on the pill can cause problems when no longer on the pill Kin Af liation Study Women who are ovulating spend less time talking with dad based on phone records Endocrine Disruptor Ex BPA phthalates Act like estrogen bind estrogen receptors reduce sensitivity Much of what we consume can interfere with endocrine systems Ignobel Award Paper Exotic dancers earn much more during estrusovulation than when not during peak fertility What might explain a preference for similar MHC genes during pregnancy Sexual partner more testosterone more dominant likely to have lower fidelity Social partners less dominant lower testosterone better parental care Appears to be a hormonal basis for lovesickness after copulation 92414 Only real difference between endocrine amp nervous system is release into blood stream vs release at synapse Integumentary System Integument includes skin glands nails hairs etc 0 Binds and protects body from external environment 0 Allows for thermal regulation through vasoconstriction and vasodilation Layers of Skin Epidermis 0 Primarily made of keratin structural protein 0 Produced by keratinocytes I dead on surface of epidermis OOOOO Dermis 0000 O I Roughly 40 day life cycle until sloughed off body I Also produce vitamin D Only bare nerve endings in epidermis in hair follicles etc Dendritic cells initiate immune response Tactile cells detect light touch with high resolution Melanocytes produce 2 types of melanin to be taken up by keratinocytes Stratum Corneum Lucidum I Outer layer of dead skin cells I Lucidum only found in thick skin in soles of feet and palm of hand I Prune skin hydrophilic layer of skin in stratum corneum absorbs water and forms waves 0 Will not form without afferent innervation Stratum Granulosum Stratum Spinosum Stratum Basale Connective tissue base for epidermis Most Somatoreceptors exist here Largely collagen Lamellar corpuscles detect deeper touch encapsulated Papillary layer I Lots of blood vessels provide nutrients to epidermis by lamellar papillae Reticular layer I Stretch marks and tearing of collagen can occur between two layers Hypodermis O 0 Hair Adipose connective tissue I subcutaneous fat Highly vascularized Keratin forms hair way keratin is arranged determines shape round straight oval curl Eumelanin and pheomelanin dictate hair color Gray hair grows with a hole in the middle Skin Color Production of melanin and distribution in keratinocytes Melanin is distributed on sunny side of nucleus 0 Protects DNA from UV light causes mutations Amount and Ratio of eumelanin to pheomelanin determines skin color 0 O O Eumelanin leads to darker skin color Body can produce more melanin in response to higher UV exposure Higher degree of melanization are defense against higher UV exposure long term Evolution of skin tone Altitude variation at high altitude Where atmosphere blocks less UV or closer to equator Where greater sun exposure darker skin Variation based on foliage in region of development high foliage lighter skin gt need UV light to make vitamin D to absorb calcium lightening of skin tone in regions of less sun exposure UV easily breaks down Vitamin B9 or BC folic acid Cultural preferences for color leading to selection Skin Burns 0 Partial thickness burns cause death of melanocytes 0 2nd degree causes death of dermis cells 0 3rd degree full thickness burn into hypodermis 39 Only regrow skin from margins or grafts Why do modern humans appear de cient in Vitamin D 0 Spend so much time indoors reduced UV exposure 39 Clothing covers skin 0 Is dietary vitamin D functioning similar to skinsynthesized vitamin D 0 Symptoms 39 Osteoporosis l some cancers may be in uenced by low vitamin D levels I rickets 0 Seasonal Affective Disorder 39 Convert serotonin to melatonin at night I Less exposure to sunlight darker more often more melatonin Vitamin D3 and Calcitriol UV light converts cholesterol derivative into vitamin D3 cholecalciferol Liver forms calcidiol Kidneys add OH to form calcitriol active form of Vitamin D Calcitriol O Resorption of Calcium from bone by osteoclasts 0 Increase absorption of calcium from food 0 Resporption of Ca from kidneys 92614 Bone Composite of collagen fibers and hydroxyapatite crystals Ca3PO42 Resistant to compression on long axis Flexibility on short axis not long axis Compact and Spongy Bone Spongy Bone O Lattice structure of interconnected fibers open structure w lots of connections Compact Bone O Coiling helices of collagen and fibers running in opposite directions up and down long axis 0 Osteon helices surrounding blood vessels in central canal 0 Running helices in opposite directions mean bone can be very thin but resist strain very well I Fewer coils in area more exible more less exible Load Bearing amp Wolff s Law Hollowing in diaphysis shaft allows for marrow and keeps bone light Epiphysis filled with spongy bone with trabeculae that are curved to dissipate stress in different directions Wolff s Law structure of bone tissue is determined by forces bone experiences 0 Spongy vs compact depends on types of stresses 1 plane vs multiplane 0 use it or lose it with bone Bone Development Osteogenic cells in early stages of formation of bone in fetus become osteoblasts Osteoblasts deposit bone matrix lots of rough ER and mitochondria Osteocytes osteoblasts that have become entrapped in matrix they produced 0 In tiny cavities amp connected to other cavities by small canals O Detect strain in bone I remodel bone from inside out 0ste0clasts derived from bone marrow contain lysosomes to dissolve bone matrix 0 Large multinucleate cells formed by fusion of cells 0 Ruf ed border adjacent to bone surface secrete HCl and enzymes to break down collagen and bone matrix Intramembranous Ossification 0 Forms at bones skull sternum clavicle 1 Mesenchyme intermembranous uid turned into osteoid by mesenchymal cells 2 osteoblasts deposit hydroxyapatite on osteoid 3 osteocytes form as osteoblasts trap themselves in matrix blood vessels and marrow cavities grow smaller and more constricted 0 at bone periphery periosteum develops from mesenchyme differentiation 0 honeycomb of spongy bone forms with periosteum 4 compact bone grows leaving spongy bone interior Endochondral Ossi cation 1 mesenchyme forms hyaline cartilage that fills perichondrium forms early cartilage model of bone 2 primary ossification center forms chondrocytes expands size of cartilage model 0 lacunae and bony spurs starts to form periosteam produces osteoblasts to mineralize outer edges to form bony collar 3 bone becomes vascularized formation of primary marrow cavity as hyaline cartilage is dissolved by arriving osteoclasts from blood 0 secondary ossification center forms at end of bone 1 in short both ends in long I helps bone to grow during childhood 4 at birth diaphysis with vascularization and marrow cavities amp epiphysis with marrow cavity and vascularization O metaphysis area between diaphysis and epiphysis where bone elongation occurs I in epiphyseal plates where cartilage is replaced by bone I easily visible under Xray lack of mineralization where cartilaginous material is growing bone I forms weak points in young bone 5 secondary marrow cavities filled in with spongy bone 0 bone inside diaphysis is dissolved and bone deposited on outside to grow bone 0 recycling of calcium can result in imperfections in bone development Appositional Growth and Remodeling bone replacement occurs rate of lOyear appositional growth increase or decrease bone wall width in diaphysis and epiphysis Bone Fractures and Healing O Nondisplaced minor crack can often heal without intervention 0 Displaced Comminated compound greenstick I Bone needs to be reset in loadbearing formation 1 hematoma bleeding converted to granulation tissue 2 soft callus formation deposition of collagen and fibrocartilage 3 hard callus formation temporary bony collar forms as minerals are deposited 4 bone fixed as osteoblasts return to function Osteoporosis 0 Calcium from bone stripped away for use by other organ systems 0 Often age related estrogen and testosterone support bone density 0 Mitigate osteoporosis I Don t run in calcium deficit I Build bone density while younger to maintain bone density 92914 Vitamin DCalcitriol Rickets widely eliminated by availability of fresh milk I Ca source augmented with vitamin D supplements 0 Postindustrial rickets children drink too much soda phosphate gets bound Hypercalcemia Inhibition of neurons and muscle cells extra Ca binds surface of cells and hyperpolarizes them or binds voltagegated Na channels amp prevents from opening Can result in mineralization of tissues other than bone Rare but awful Leads to release of massive quantities of calcitonin from thyroid 0 Within minutes limits osteoclasts excites osteoblasts Hypocalcemia Much more common Parathyroid Hormone O Increases synthesis of calcitriol excites kidneys to add last OH group O Increases osteoclast activity decreases osteoblast activity 39 Occurs via binding osteoblasts with rankle I In juveniles to reduce high blood Ca need more Ca available for bone deposition 0 Promote loss of phosphate through urine 0 Less calcium excretion through urine Why have Calcium homeostasis Muscle contractions neural function bones cell signaling Correct Hypercalcemia O Calcitonin primarily effective in juveniles effects in adults are weak Correct Hypocalcemia 0 Parathyroid hormone Of 206 human bones many irregularities for bipedalism I causes problems Humans are about 2 million years old share common ancestor with apes 20 million years Shift puts center of balance medial to attachment of leg to hip O Reduces strain on knees allows standing upright without constant muscle contraction O Pelvis formed a cup to support viscera I creates a small aperture for childbirth I Creates painful childbirth O Scurved vertebral column centers mass over feet 0 Shorter face keeps head centered and face up 10114 Muscle If calcitriol increases osteoclast activity how can calcitriol de ciency lead to bone softening rickets Inhibits osteoblasts increases activity of osteoclasts Calcitriol stimulates Ca2 absorption from food I without calcitriol less is absorbed and Ca is pulled out of bone 0 Acts more quickly to excite active transport to get more Ca from food 0 If food not sufficient then it removes calcium from bone Types of Muscle tissue Skeletal 0 Voluntary striated can be in uenced by autonomic processes 0 Large long multinucleate cells I develop from fusing of multiple stem cells 0 Lots of mitochondria 0 Produce heat stability manage amp store glucose as glycogen Smooth 0 Doesn t have striations involuntary O Often occurs in tubes ex sphincters slower to contract amp relax Cardiac 0 Has features of both skeletal and smooth muscle Skeletal Muscle Hierarchy Muscle fibers bundled together in fascicle and surrounded by perimysium Fascicles are bundled together and surrounded by epimysium Epimysium wraps individual muscle Fascia wraps entire muscle group defines a muscle compartment 0 Blood vessels and nerves contained in connective tissue Lots of connective tissue binding bundles together relatively in exible Significant blunt force trauma can cause buildup of blood or extracellular uid in muscle compartment I compartments don t increase in size so swelling doesn t occur I increase pressure on muscles amp can cause severe necrosis of tissue Muscle surrounded by epimysium I fascicle in perimysium I muscle fibers cells Skeletal Muscle Fiber Each cell contains many myofibrils protein filaments that are composed of myofilaments Multinucleate cells with mitochondria between myofibrils Triad ttubule surrounded by terminal cisternae of sarcoplasmic reticulum run transverse to fiber Myofilaments 0 Thick Filaments l Myosin shaped like 2 golf clubs twisted together I Heads of myosin not evenly distributed along thick filaments I Myosin filament heads point in different directions at each end 0 Thin Filaments I Actin troponin tropomyosin I Factin filamentous Gactin globular amp unpolymerized I Each actin has a binding patch for myosin I T ropomyosin arranged in strips blocks myosinbinding sites on actin I T roponin Calciumbinding protein which changes tropomyosin conformation O Filaments arranged in alternating fashion bare zone is just myosin tails Dystrophin binds thin filaments to sarcolemma to endomysium through linking proteins 0 Allows muscle fibers to transmit force to rest of body Elastic filament connects thick filaments to zdisc Muscular Dystrophy 0 Problem with expression of dystrophin makes connection insufficient for normal muscle function Sarcomere area between zdiscs Aband area in which thick filaments exist H band bare zone of thick filaments Mline thick filaments connected by regulatory proteins to keep filaments parallel Iband space between thick filaments Zdisc regulatory proteins that anchor thin filaments amp bind elastic bands 10314 dystrophin most important connective protein in force transfer in muscle sarcomere membrane Neuromuscular Junction Motor End Plate Motor units all muscle fibers controlled by 1 motor neuron 0 Size of units can vary from 15 few small motor unit fine motor control 0 1200 many large motor unit powerful contraction less control 0 Muscle fibers controlled by a given neuron evenly distributed throughout muscle Schwann cells myelinate and maintain synaptic knob Basal lamina collagenous casing surrounds entire junction to isolate it 0 Allows for even higher concentration gradients Junctional folds increases surface area of sarcolemma to allow for more receptors I makes muscle more sensitive to ACh 0 ACh receptors ligand gated Na channels Resting membrane potential 90 mV as compared to 70 mV in neurons Motor End Plate potential 70 mV as compared to 35 mV in neurons Excitation near Neuromuscular Junction 0 O O EPSP Hydrolysis cause ligandgated channels to open and use NaCa to push muscles toward firing Norepinephrine raises resting potential so muscles are prepared to respond IPSP inhibitory neuron presynapticallyinhibits synaptic knob 39 Uses GABA or glycine to open Cl channels into synaptic knob hyperpolarizes motor neuron to prevent action potential I Very common prevents unwanted firing Tetanus prevents release of inhibitory neurotransmitters in CNS get undesirable release of ACh I causes overstimulation amp violent contractionsparalysis of muscle Pesticides and neurotoxins act in the same way uninhibit motor neurons and prevent reduction of ACh in synaptic cleft I constant muscle firing Hypocalcemia Ca binds negativelycharged large proteins on exterior of cell to allow for larger membrane potential I makes cell closer to action potential Excitation at NMJ O 0000 0 Action potential arrives at synaptic knob Vesicles release up to 60000 molecules of ACh into synaptic cleft 2 ACh bind each receptor I opens ligandgated ion channels C32 and K ow intoout of cell respectively through same channel Large depolarization adjacent areas of sarcolemma open voltage gated NaK channels I signal has a sort of ripple effect AChE acetylcholinesterase decomposes ACh in absence of action potential ExcitationContraction Coupling O O 0 Links endplate potential to muscle fiber Action potential propagates depolarization down sarcolemma through ttubales that distribute signal throughout width of muscle fibers Coupled with terminal cisternae of SR Ca2 channels open in response to depolarization in ttabales Flood of Ca2 into cytosol triggers contraction in sarcomere Contraction O Ca2er binds troponin complexes and reorients tropomyosin opening myosin binding sites In myosin head myosin ATPase hydrolyzes ATP I ATP P and causes cocking of myosin head Myosin crossbridge forms as myosin binds thin filament ADP released from myosin head causing myosin to uncock in power stroke 0 Myosin remains bound until ATP binds myosin breaks crossbridge Relaxation O AChE removes ACh from synaptic cleft 0 Terminal cisternae sucks up free calcium and stores it with calsequestrin 0 Antagonist muscle must contract to stretch out first muscle Rigor Mortis Body muscles contract 34 hours after death Decomposition of SR releases free Ca into muscles I crossbridges form can t release wo ATP 23 days after death rigor mortis subsides 0 Myofilaments and myofibrins amp dystrophin break down 10614 Skeletal muscle PGClal may mediate resilience to stressinduced depression 0 Aerobic exercise can help protect against depression kynurenine produced under stress and can cross bloodbrain barrier and prevent depression Muscle contraction builds internal tension I not necessarily shortening muscle 0 Thin filaments are moving toward the mline of each sarcomere bring zdiscs closer together Muscle tone maintain certain level of internal tension to reduce slack time before external traction occurs 0 Motor units activate in cycle to maintain muscle tone so motor units don t fatigue over time Types of Contraction Isometric muscle develops tension but doesn t shorten O ie hold a heavy object Isotonic concentric muscle shortens while tension remains constant 0 ie lifting an object Isotonic eccentric muscle lengthens while tension remains constant 0 Tension slows descent of object 0 Most often source of injury Muscle Twitch Strength of contraction More action potentials more motor units activated I temporal summation Threshold stimulus required to stimulate activity in muscle 0 Latent period 2 ms excitation and excitationcontraction coupling and contraction to build up internal tension O Contraction phase shortening of muscle amp exertion of contractile force I Known as a twitch shortening in response to threshold stimulus I Requires continual stimulation because free Calcium would be used up and reabsorbed by calsequestrin I At higher body temperatures muscles work faster enzymes work better I Muscle fatigue fuels needed have been consumed I Hydration lower body water levels reduce cytosol levels 0 Thicker cytosol hinders movement of ATP and glucose I Lengthtension relationship 0 Overstretched too few crossbridges can form low tension 0 Overcontracted heads reach bare zone amp not able to form new crossbridges O In body antagonists keep muscles stretched so they are in optimal overlap region I Stimulus Intensity C More action potentials to more motor units pushes muscle toward maximum contraction motor unit summation 0 Relaxation phase without stimulus muscle relaxes Stimulus frequency 0 Stimuli spread out over time twitches to remove internal slack o Enough stimulation temporal summation I Steadily increasing levels of tension in muscle 0 Overstimulation complete tetanus I Muscle is so overstimulated that all myofibrils are fully shortened and can t relax 10814 Muscle Lecture 4 Muscle Strength Temporal summation of action potentials and twitches Composition of Muscle Proportion of fibers determine how strong contraction is SlowTwitch red O Remain tensed longer than fasttwitch fibers Consume less ATP to contract for longer period of time Oxidative fibers specialized for aerobic respiration More myoglobin stored Smaller motor unit Lots of large mitochondria FastTwitch white OOOOO Faster to generate tension Consume more ATP I switch to anaerobic production of ATP glycolytic fibers Store more creatine phosphate and glycogen 0 Larger motor units Muscles can t really adapt fasttwitchslowtwitch ratio to what they are used for 0 Difference appears to be genetic 0 Limited mitosis of skeletal muscle cells prevents this I Do not regenerate muscle tissue 0 Muscle growth cells get larger by adding more myofibrils and myofilaments I Hypertrophy I Storage of additional glycogen and myoglobin OOO Muscle Cramps Lack of ATP means crossbridge can t break muscles can t relax until ATP arrives Motor units unable to relax antagonistic muscle contracting tearing against one another Fatigue in CNS Lack of NaK ions needed to maintain membrane potential Muscle fatigue lack of glucose lack of oxygen lower ATP levels Glycogen Large branching storage molecule made of glucose subunits Liver breaks down to glucose needs to be converted to ATP Glycolysis 2 ATP per glucose Aerobic respiration 36 ATP per glucose ATP and Exertion Short duration high intensity exercise too soon for body to catch up with oxygen 0 Initial movement uses aerobic respiration 0 Phosphagen system for next 610 seconds 0 Glycogen lactic acid system 3045 seconds until circulatory and respiratory system catch up Phosphagen system 0 Myokinase takes P from ADP and add to another ADP to make ATP AMP 0 Creatine kinase uses P from creatine phosphate making ATP 0 Creatine supplements makes more material available for phosphagen system in anaerobic state I Taking creatine with exercise can lead to rise in testosterone level Muscle Fatigue 0 Buildup of lactic acid in muscle is thought to lead to muscle fatigue and soreness O Buildup of K outside cell and ADP and P could contribute to fatigue and soreness 39 Can inhibit slidingfilament mechanism 0 Loss of essential ions etc Muscle Arrangement 0 Different muscle types can contribute different amounts of forcestrength O F usiform lots of contractile force biceps brachii 0 Parallel smaller amounts of force rectus abdominis O Relatively few voluntary muscle fibers Smooth Muscle Peristalsis rhythmic movement created by alternating contractions 0 Moves food through digestive system Do not fatigue very easily Contractrelax slowly powered aerobically need to maintain smooth muscle tone constantly 0 loss of tone in artery expanding vessel blood pressure plummets faint dense bodies protein plaques that bind to actin filaments less structured filament organization 0 contraction leads to shortening and thickening of muscle Ca2 pulled from extracellular uid through gated channels END OF EXAM 2 101514 HEART Skeletal vs Smooth Muscle Striated vs nonstriated Voluntary vs involuntary Multinucleate v uninucleate Large v small Fast contraction v slow contraction Smooth Muscle Cells Fusiform small Contractile mechanism 0 Web of thin filaments held together at dense bodies instead of z discs 0 Tough cytoskeleton transmits contractile mechanism to exterior of cell 0 Cells shorten and thicken upon contraction Excitation v Inhibition 0 Action potentials neurotransmitters Temperature Pressure or stretching Some are autorhythmic Calcium ions not stored in cell gated ion channels let Ca2 into cell 0000 Cardiomyocytes Heart can beat when removed from body until it runs out of ATP Large thick Uninucleate Lots of mitochondria and glycogen I aerobic respiration Large Ttubules allow Ca2 in from outside cell Intercalated disc Notched jagged ends allow cells to be in contact with multiple others 0 Desmosomes Intermediate filaments of one cell are connected to the others 0 Gap junctions allow diffusion of ions for communication Connective Tissue of Heart Most of heart is muscle Heart is encased in unfolded uidfilled sac I pericardial sac 0 Infection is very bad here Cardiac Cycle Blood pumped through right side of heart supplies pulmonary circuit Left side of heart supplies systemic circuit Valves between atria and ventricles open passively as pressure builds and muscle shape changes Systole contraction of ventricles Diastole relaxation of ventricles Ventricles contract simultaneously with equal volumes if not causes edema Cardiac Conduction Cycle Sympathetic affects contractile strength parasympathetic affects contractile rate Heart is autorhythmic Sinatrial node SA node pacemaker of the heart 0 Patch of myocardiocytes with unstable resting membrane potential 0 Gradually depolarizes every 08s 75 bpm 0 Cells leak Na into cells amp don t leak K I leak up to 40 mV action potential triggered by voltagegated Caz channels also helps contraction 0 Around 0 mV K channels open and repolarizes cell Signal passes through right atrium Atrioventricular node AV node 0 Small cardiocytes with fewer gap junctions create a pause in signal 0 Signal pauses to allow atrium to contract and blood to fill ventricles before contraction Atrioventricular bundle Purkinje fibers 0 Signal spreads down interventricular septum and then up side walls I allows bottom of ventricle to contract first Most cardiocytes have slow uptake of Ca2 I lengthens contractions amp refractory period 0 250 ms vs 12 ms for skeletal muscle 0 Prevents fatigue of cardiac myoctes Electrocardiogram EKG Record rhythm of heart and see abnormal conduction Sinus rhythm P wave first bump signal spreading from SA node to right atrium O PQ segment contraction of atria just after P wave QRS complex AV node signal leads to depolarization of ventricles O Bigger signal because more cells are being depolarized 0 ST segment Contraction of ventricles T wave repolarization of ventricles Can t see repolarization of atria obscured by QRS complex Uses of EKG Arrhythmias improper contraction andor conduction rhythm of heart Ventricular fibrillation lack of rhythm in heart contraction 0 Inefficient or lack of blood pumping O Occurs during myocardial infarctions obstruction of blood supply Emergency defibrillation can help SA node to reexert control over heart 0 Don t address underlying condition Atrial fibrillation abnormal P waves 0 Irregular depolarization of atria Heart block QRS complex not always there poor T wave 0 Signal is not being transmitted through the AV node properly Premature Ventricular contraction signal moves too quickly to ventricle O Ventricles contract before they fill with blood 0 Can get inverted and misshapen QRS complexes elevated T wave WolfParkinsonWhite Syndrome 0 Extra contractile route I signal that moved up ventricular walls can feed back to right atrium O 0 102014 Blood Creates 2nd conduction pathway delta wave slurring of QRS complex amp shortening of interval of atrial contraction Can lead to ventricular fibrillation sometimes Circulatory System Liquid connective tissue 55 plasma ltl buffy coat leukocytes and platelets 3752 erythrocytes Roles O O O Plasma 00000 0 transport protection regulation Water 92 wv Proteins mostly albumins determine viscosity and osmolarity of blood Nutrients ElectrolytesIons Nitrogenous wastes Other Components Formed Elements contained in membranes 0 O O Platelets cell remnants Erythrocytes 5 leukocytes Erythropoiesis Postnatal Red bone marrow produce red blood cells Hypoxemia detected by liver and kidneys I secretion of hormone erythropoietin EPO I stimulates increase in production of red blood cells Prior to birth liver and spleen play large role in RBC production Red bone marrow produces formed elements Lymphatic system produces white blood cellsleukocytes Causes of hypoxemia Disease states high altitudes cardiovascular exercise Erythrocytes Biconcave disc in large vessels I shape changes to squeeze through capillaries 0 Unusually superficial no nucleus limited cytoskeleton 0 No mitochondria don t use oxygen they are transporting 13 of content of RBC is hemoglobin 0 Heme group Fe containing compound that carries oxygen High rate of turnover 1 millionsec 100 billionday 0 Live for 120 days dead cells caught and broken down in liver and spleen Anemia low levels of RBCs and bloodoxygen 0 Sickle Cell Anemia I Poor oxygen transport and can block blood vesselscapillaries I Disease Chronic misshapen Hemoglobin 0 Homozygous recessive for sickle cell allele 0 Most frequently in recentAfrican or Mediterranean ancestry I Benefit heterozygous individuals have cells that form sickle cell shape When infected With plasmodium malaria 0 Allows for easy detection and destruction of diseased RBCs Blood Types ABO Rh 0 Antigen markers made by glycolipids mark self vs nonself 0 One locus 3 allele determination system I 2 dominant alleles A and B I 1 recessive allele 0 0 In blood antiA and antiB antibodies depending on blood type agglutinins I Bind to multiple RBC antigens and create aggregates 0 Rh Factor I If you have it or don t I Considered next most important for medicine 0 Many other antigens on RBCs I chance of adverse reaction even With same blood type I Way around it I receive plasma instead of Whole blood to increase blood volume 102214 Read 135 and 141 fri 123 amp 142 Erythropoiesis Colony forming units erythropoietin I erythroblasts form and synthesize hemoglobin I mature in bloodstream I circulate for 120 days I worn out cells trap in spleen and liver I hemoglobin degraded Blood Vessels Arteries 0 Higher elastic tissue content to handle pressures from blood coming from left ventricle prevent aneurisms O Elasticity allows for moderation and equilibration of pressure Veins Tunica interna O Secretes substances to prevent formed elements from adhering to wall Tunica media 0 Thickest layer muscular amount varies based on location 0 Elastic in arteries Circulatory Homeostasis Important to maintain blood pressure against gravity and position changes Baroreceptors in aortic arch above heart and chemoreceptors in the internal carotid artery detect lowered pressure 0 Signal medulla oblongata to signal to heart via vagus nerve to speed up heartbeat to raise pressure to normal 0 Elevated pressure leads to higher receptor firing rate I vasodilation and reduced heart rate I decreases blood pressure Local Control 0 Cells of tunica interna can detect blood pressure and can secrete chemicals to affect blood pressure in local area Redirection of Flow 0 Dilation and constriction of arteries can decrease blood ow to one area and increase it to another based on need 0 Exercise 75 of blood to muscles l blood also sent to skin to release extra heat Capillaries walls only about 1 cell layer thick if all capillaries open all the time not enough blood to fill them all continuous capillaries 0 thin continuous wall with tight junctions amp intercellular clefts for large molecules to pass through fenestrated capillaries 0 located where rapid absorption or filtering occurs 0 larger openings for filtration sinusoidsdiscontinuous capillaries O in liver and hemopoiesis organs 0 contact between blood and cells of organs precapillary sphincters muscles around heads of capillaries alternate opening and closing to allow blood to ow to different tissues O 5 of blood in capillaries at any given time Blood Pressure Pressure decreases drastically with distance from heart Important to measure blood pressure at level of heart gravity and distance have large role High systolic pressure can lead to aneurisms Arteriosclerosis amp atherosclerosis loss of elasticity amp lipid deposition on wall 0 Loss of size of vessel higher blood pressure Venous Return Have oneway valves to keep blood moving to heart Skeletal muscles compresses vessels to push blood toward heart Hemostasis Vascular spasm vasoconstriction to create blockage Platelet plug formation platelets release clotting factors and bind site of injury Coagulation cells and protein web form clot 102414 Lymphatic System Routes of Capillary Exchange Diffusion down concentration gradients glucose hormones oxygen carbon dioxide Filtration pores very thin glycoprotein membrane allows for large molecule transport 0 Easier movement of materials Transcytosis Diffusion and movement in through continuous capillaries is slower than through fenestrated capillaries Filtration and Reabsorption Plasma moves into and out of capillaries Solvent drag with movement of uid you get movement of all that is dissolved as well Hydrostatic pressure in arteries 33 out 20 in net pressure of 13 out 0 Colloid osmotic pressure pressure due to presence of proteins on one side of capillary wall ex albumin I More proteins in plasma than interstitial uid water driven down its concentration gradient 0 Oncotic pressure pressure from interstitial space on capillary Hydrostatic pressure in veins 13 out 20 in net pressure of 7 in O Occurs because oncotic pressure stays the same but colloid osmotic pressure decreases as blood pressure decreases O Drives filtered plasma back into capillaries O Accumulation of filtrate lowprotein plasma Within the tissues and organs or in interstitial space 0 Only 85 of uid is generally absorbed back into capillaries moved back by lymphatic system 0 Can interfere With capillary exchange increases tissue pressures Functions of Lymphatic System Absorbs dietary lipids Hosts immune system Recirculates lymph back into circulatory system 0 Larger vessels of lymphatic system associate closely With larger arteries and veins movement of lymph is assisted by skeletal pumps of veins and contraction of arteries Lymphatic vessels resemble structure of veins 0 Walls are not stitched together as tightly as veins I allows particulates and large molecules to 0 Have oneway valves to keep lymph moving in right direction 0 System converges on 2 collecting ducts I release lymph into subclavian vein Lymph Nodes 400500 in the body Cleaning and ltration foreign matter cell debris etc is removed and filtered from lymph Immune system screening leukocytes stay in lymph nodes and screen lymph for nonself targets 102714 ImmuneLymphatic System Leukopoiesis WBCs originate in red bone marrow but don t all mature there Leukocytes WBCs Neutrophils 0 Most common 0 Bacterial defense attack pathogens by phagocytosis 0 Respiratory burst release hypochlorite and hydrogen peroxide kill everything in an area Eosinophil 0 Located in mucous membranes primarily O Specialize on noninfectious irritants amp parasites Basophils 0 Release histamines that increase blood ow heparin is clotting inhibitor 0 Makes it easier for other WBCs to arrive and address potential problem Lymphocytes Monocytes 0 Migrate into tissues and differentiate into macrophages 3 Lines of Defense 1St line Skin Mucous Membranes Dendritic cells identify foreign organisms and present antigens for attack Creates a physical barrier that prevents entry Secretes acid mantle that prevents bacterial growth 2nd Line Fever and in ammation 0 In ammation hyperemia I Both exogenous and endogenous signals I Tissue damage releases histamine and heparin signals basal amp mast cells I vasodilation to get WBCs there faster I Make capillaries more permeable and sticky to hold WBCs near area I WBCs margination diapedesis chemotaxis phagocytosis 0 Fever I Tissues release endogenous pyrogens that reach hypothalamus and adjust body thermostat to higher set point I Triggers mechanisms of heat retention 0 Shivering to raise body temperature I May slow bacterial growth amp speed up immune response 0 People with fevers often recover faster I Defervescence profuse sweating amp vasodilation cools body Nonadaptive WBC response 0 Natural Killer Cells I Attack diseased cells and pathogens I Use perforin to create a hole in cells insert granzymes to degrade proteins Antimicrobial proteins complement 0 Bind plasma membrane of foreign organisms and create pores with perforin 102914 Immune System 5 types of Leukocytes Neutrophils 0 Most common phagocytosis amp respiratorv burst sodium hypochlorite Easinophils 0 In mucous membranes of body tracts 0 Interact with large parasites amp allergens 0 Stimulate basophils Basophils O Facilitators secrete signaling proteins leukotrienes to alert other cells 0 secrete histamines vasodilation O secrete heparin prevents clot formation amp agglutination I can get swelling bleeding in ammation etc 0 mast cells connective tissue cells have same function as basophils Monocytes 0 Migrates into tissues I changes in macrophages for phagocytosis 0 Dendritic Cells I Move into cells I differentiate I communicate I Similar to macrophages Lymphocytes Neutrophils amp macrophages release pyrogens to cause a fever 0 Assist with controlling infection Fever At pyrogen levels rise hypothalamus changes set point 0 Correction in response to signal w reversal when signal dissipates I negative feedback 0 Positive feedback out of control fever What do measles mumps rubella and polio but not smallpox have in common Vaccinations made smallpox extinct in wild MMR amp polio vaccine I why do they still exist 0 Some people are choosing not to vaccinate children for MMR in US amp Europe 0 Not allowed to get polio vaccine Pakistan Afghanistan north Africa I Religious fundamentalists against vaccination campaign Specific Immunity adaptive Recognize amp remember specific antigens Vaccination creates antibodies Cellular Immunity 0 Cytotoxic T cells 39 Attack foreign cells amp infected host cells 0 Use same techniques as natural killer cells Humoral Immunity 0 Attacks cells viruses small infectious agents toxins etc before they attack cells Respond to antigens larger chemicals glycolipids glycoproteins etc that are of nonself Respond to haptins foreign chemical forms complex with endogenous proteins I complex recognized as foreign by mast cells connective tissues 0 Can cause allergic reaction B lymphocytes 0 Originate in red bone marrow 0 Mature in bone marrow 39 Tested for selftolerance amp immunocompetence gt about 2 pass 39 Antigenpresenting cells test t cells for selfrecognition 0 Cells that pass are cloned and distributed throughout lymphatic system T lymphocytes 0 Originate in red bone marrow O Migrate to thymus for maturation I Maturation is same as above Immune Response Step I recognize nonself Lots of cells can be antigenpresenting cells 0 Break down pathogens amp present relevant antigen parts on surface B cells T cells reticular cells of thymus mast cells can react to antigens 0 Through MHC proteins that bind antigens T cells 0 Helper T cells bind MHCantigen complex amp cobind with another protein on antigenpresenting cell I failsafe to ensure no attack of self I Helper T cells coordinate immune response by 0 Promoting nonspecific response 0 Recruit WBCs and provide clonal selection of B cells 0 Promote replication of cytotoxic T cells 0 Release protein signals to elicit largescale immune responses 0 Triggers clonal selection T cell creates many copies to recognize same antigen again 0 Cytotoxic T cells recognize antigen and attack the infected cells I Can produce interferons to prevent viral replication use granzymes to create holes 0 Memory T cells small number of longlived lymphocytes that embed in lymphatic tissues to recognize these antigens in future I much faster amp more robust response in future HIV Specifically targets helper t cells I makes body susceptible to cancer and other viruses Humoral Immunity B lymphocytes 0 Can process amp present antigens on MHC proteins on surface 0 Helper T cells confirm ID of antigen amp recruit cytotoxic T cells 0 clonal selection amp production of antibodies immanoglobins Antibodies 0 Bind antigens can eliminate threats or signal other cells to react 0 Hypervariable region is antigenbinding site 0 Can block active site of toxinvirus to prevent interaction With cells 103114 Antibodies 0 Interact With antigens in hypervariable antigenbinding sites 0 Neutralization bind active sites of antigen to prevent interaction With body 0 Complement Fixation antigens change shape when binding antigens and bind complement and trigger the response 0 Agglutination chains and clumps of cells bound together by antigenbound antibodies slows movement and makes easy targets for cytotoxic T cells 0 Precipitation makes proteins amp toxins insoluble in blood immune clearance of these clumps occur in liver amp spleen Humoral Immunity Natural Arti cial Passive Maternallyacquired Immune serum Active Previous exposure Vaccination Primary amp Secondary Immune Response 0 Initial antigen build up takes 1520 days during primary response 0 During secondary response I Within 2 days IgG antibody levels spike much higher than during initial response lasts longer than initial response Respiratory System Respiratory Tracts Upper tract nasal passages epiglottis pharynx trachea larynx 0 Many ciliated cells amp goblet cells producing mucus Lower tract lungs Leukocytes checking tissues for pathogens amp foreign substances Upper Respiratory Tract Vestibule of nasal cavity is small compared to nasal cavity Divided into two halves by nasal septum Passages create lots of turbulence I ensures that anything in air touches epithelium and pulls particulates out of air Erectile tissueswell body alternates swelling from one side of nose to the other alternates air ow from one nostril to the other 0 Keeps cells from totally drying out chance for tissues to recover O Prevents total habituation for olfactants Lower Respiratory Tract Trachea I bronchi 0 Food inhaled tends to lodge in right bronchus Conducting pathways bring air to gasexchange regions of lungs Hylum slit in mediastinal lung where blood vessels enter Bronchial tree 3 lobes of left lung 2 lobes of right lung 0 65000 terminal bronchioles bring air to alveoli Alveoli O Capillary network allows for efficient gas exchange 0 Respiratory membrane separating alveolar lumen from blood ow is 23 cells thick 0 Lymphocytes adjacent to capillaries alveolar macrophages in alveoli eat particulates O Delicate moisture balance of membrane I Maintained by osmosis due to oncotic pressure Pleural Cavity Visceral pleura external surface of lung 0 Separated from thoracic wall by pleural cavity area of negative pressure that keeps lungs expanding up to parietal pleura of wall 0 Moist and helps to stick together I draws lung change in shape to facilitate expansion Breathing HotCold Air Cold 0 Air is very dry and lungs are losing moisture to heat air 0 Easier to breathe because air expands as it heats I helps expand lungs Hot 0 Air is already hot I it doesn t expand or help to expand lungs Boyle s law Pressure of a gas depends on its volume Charles law volume of gas is proportional to temperature 11314 Respiratory System Dalton s law total pressure of a gas mixture is sum of partial pressures of gases Henry s Law amount of gas dissolved in gasliquid interface determined by solubility and partial pressure in air Pleural Cavity Experiences slight negative pressure when diaphragm and intercostal muscles contract Sticks to lung visceral pleura due to wetness I helps lungs expand Alveoli Highly vascularized Respiratory membrane is very thin Have to maintain liquid balance to provide optimal gas exchange Respiratory Infection Pneumonia O Describes condition rather than cause 0 Fluid and blood cells fill alveoli O Edema thickens alveolar walls Emphysema a COPD O Destruction of some alveoli O Con uent alveoli loss of surface area of respiratory membranes Results in overproduction of RBCs Higher blood pressure shunting and heart stress Respiratory Cycle Diaphragm contracts I expands thoracic cavity amp decreases internal pressure I air ows down pressure gradient into lungs Diaphragm relaxes I shrinks thoracic cavity amp increases internal pressure I air ows down pressure gradient out of lungs Composition of Air Relative composition of air doesn t change much except water vapor Partial pressures differ With altitude Much more C02 in alveolar air than inspired air amp less 02 than in inspired air Alveolar Gas Exchange C02 is much more soluble in blood than 02 I rates of transfer are different Most C02 is bound to Hb or as HCOg39 in RBCs I important to prevent blood acidification 0 Respiratory rate is mostly controlled by blood acidity not 02 levels Almost all 02 is carried by Hb on RBCs RBCs can carry both C02 and 02 concurrently Hemoglobin 0 Each heme group has Fe2 that bind 02 O Globins can transmit C02 0 Complementary binding Hb changes shape after first 02 binds to improve binding affinity 0 Higher the 02 in an area the greater the affinity for oxygen In low 02 environment Hb affinity for oxygen decreases amp 02 released 0 Saturation of Hemoglobin I Lower pH decreases affinity for oxygen 0 Tissues With high C02 amp low pH I more 02 unloading I Higher temperature reduce carrying capacity for oxygen 0 0 More likely to unload 02 to warm tissues With highest metabolism Blood pH 0 Acidosis drives H into cells K out of the cells I hyperkalemia I Inhibition of excitatory cells bc decrease K gradient 0 Alkalosis drives H out of cells K into the cells I hypokalemia I Overstimulation of excitatory cells bc pushed closer to threshold potential 0 Can occur from I Hyperventilationhypoventilation I Metabolic conditions 0 Acidosis more common Systemic Gas Exchange Carbonic anhydrase facilitates conversion of C02 into H2C03 Decreases C02 in blood generates concentration gradient that drives C02 gas into blood Antiport Cl39 is driven into RBCs as HC03 that is produced is driven into blood Free H from H2C03 binds HbOz forces Hb to release 02 by destabilizing complex Some 02 remains in blood stream as reserve in case of respiration failure 11514 Reticular Formation Gray matter nuclei among White matter tracts in brainstem Habituation to stimulation sense pain Free nerve endings O Chemicallygated or temperaturegated ion channels 0 Need associated cells to detect pressure movement mechanical stimuli Muscle spindle O In muscle fibers can detect changes in shape to detect contraction O In smooth amp skeletal muscle I In arteries amp walls of bronchi Systemic Gas Exchange Exchange mediated by RBCs 0 Can quickly absorb C02 down a strong concentration gradient Must get rid of it I becomes carbonic acid amp drops tissue pH acidosis Carbonic anhydrase catalyzes C02 change to H2C03 Antiport protein moves HCOg39 out of cell amp brings Cl39 into cell I Drives reaction to the right Le Chatlier s principle 0 H from bicarbonate destabilizes HbOz complex to force release of 02 into 000 tissues C02 transport 0 Some C02 bound to Hb protein not bound to heme groups 0 Most C02 converted to HCOg39 and carried in blood or in RBCs I H helps push 02 out of RBC to tissues that need it most 02 transport 0 Hb affinity for 02 depends on concentration of 02 I Lower levels of 02 in tissues reduce 02 affinity to cause 02 release I High levels of 02 cause Hb conformational change to increase affinity for binding oxygen Alveolar Gas Exchange Carbonic anhydrase drives reaction in reverse to produce free C02 that diffuses across membrane High 02 concentration drives H off HHb I increases affinity for 02 binding Respiratory Cycle External intercostal muscles internal intercostals amp diaphragm expand thoracic cavity Nuclei for forced respiration amp re exive breathing o In medulla and pans 0 Can in uence nuclei via motor cortex 0 Ventral amp dorsal respiratory groups in medulla I Ventral group has primary control I Reverberating circuit that goes through inspiratorv neuron then exniratorv neuron I Doral group controls responses to irritants or stimuli that affect breathing I Chemoreceptors stretch receptors irritant receptors 0 In uences ventral group 0 Pontine respiratory group in pons I In uences both ventral amp dorsal groups from higher brain functions I Can increase respiratory rates or interrupt inspiration With expiration and vice versa I Sleeping respiration rates of exercise respiration speaking respiration 0 Bypass mechanism from midbrain I spinal integrating centers Autonomic Respiratory Regulation Stretch receptors amp peripheral nervous receptors of blood pH in aorta amp central chemoreceptor in medulla monitors chemistry of CSF Hydrogen doesn t cross bloodbrain barrier easily but C02 does 0 as C02 builds in brain H levels ow down concentration gradient into cell gt K pushed out of cell I neurons get excited 0 increase ventilation to dump C02 END OF EXAM 3 111014 Excretion calcitriol weak effect on Ca2 reabsorption by kidneys PT H has larger effect at rest kidneys receive 22 of blood ow 1100 mLmin but only 04 of body mass Functions of Kidneys maintain blood volume osmolarity pH ion concentration water volume secretes erythropoietin in response to hypoxia filtering metabolic wastes drugs hormones amp neutralize free radicals produces calcitriol from calcidiol can convert amino acids into glucose I in extreme starvation Poisonous Metabolites NH3 interrupts ATP synthesis I comes from creatinine uric acid ammonia Kidneys convert ammonia to urea o If blood urea nitrogen BUN levels are too high I azotemia uremia 0 Heart arrhythmia shortness of breath convulsions amp death Fish amp amphibians just dump ammonia into water Competing needs Disposal of nitrogenous wastes water conservation amp electrolyte balance Renal Anatomy Situated about rib 12 right kidney is lower because of liver Renal medulla where filtration occurs 0 Renal DVramids 612 per kidney area of cortex form functional unit known as renal lobe 0 Renal papilla end of pyramid ends in point that feeds into calyx that carries urine away 0 Renal Column separate pyramids amp provide space for arteries amp veins Renal cortex surface portion Blood Supply Renal artery I segmental artery I interlobar artery I arcuate I cortical radiate I afferent arteriole supply blood to functional unit I glomerulus I peritubular capillaries I cortical radiate veins I arcuate veins I interlobar veins I renal veins Nephrons 12 million per kidney Renal Corpuscle Glomerulus blood vessels surrounding capsule o Bowman s capsule where filtrate enters Renal Tubule Renal Corpuscle 0 Regulation of blood ow to corpuscle by smooth muscles of afferent arterioles 39 Contract when stretched high blood pressure to keep BP from getting too high I maintain a filtration pressure 0 Larger afferent arteriole than efferent arteriole keeps pressure high to create filtration Renal Tubule 0 Thin segment larger surface area I diffusion of water 0 Thick segment smaller surface area I transport of ions 0 Proximal convoluted tubule I nephron loop I distal convoluted tubule I collecting duct I papillary duct Renal Innervation Renal artery surrounded by renal plexus of nerves amp ganglia of svmpathetic nervous svstem amp sensory afferent nerves pain receptors Nerves follow arteries into each nephron O Needed to regulate blood pressure I assist m hormone is maintaining blood pressure via water balance 111214 Excretion 2 4 Steps to Make Urine Glomeural filtration 0 Most wastes leave blood as solutes in water lowprotein plasma 0 Flows through fenestrated capillary wall into capsular space 0 Basilar membrane very thin net of glycoprotein keeps larger molecules in 0 Basement membrane negativelycharged gel on capsular side that turns away small anionic compounds like albumin Small ions pass through unless bound to plasma proteins High blood pressure in capillaries forces uid out 0 Efferent arteriole higher hematocrit higher osmolarity more viscous much 00 liquid is passed through capsule 0 How can prolonged exercise damage ltration membrane I Redirects blood ow away from kidneys I get hypoxia of cells of kidney wall I protenurea protein gets into urine I Hematourea blood in urine due to kidney failure 0 Kidneys filter 150L180Lday I High blood hvdrostatic pressure low colloid osmotic pressure capsular pressur positive filtration pressure I Hypertension can cause glomerular scarring reduces filtration rate Tubular Reabsorption O Proximal Convoluted Tubule 65 of recovered uid I Concentration gradient set up for movement of other materials as well I 6 of body ATP used to reabsorb ions from tubular uid I Transcellular route I Symport Na amp glucose in use ATP Antiport Na in for H out or C1 in for anions out Steep osmotic amp electric gradients facilitate movement Transport maxima limited number of ports max rate of transfer if concentration of ions is too high I won t get complete recovery 0 Aquaporins move some water back into blood I Solvent drag much of nitrogenous wastes excreted are pulled back into blood by water paracellular route I High tissue hvdrostatic pressure low blood pressure high blood colloid osmotic pressure high ow into capillaries O Angiotensin II alters vasoconstriction to lower capillary blood pressure increased level of reabsorption of water amp dissolved solutes 0 Loop of HenleNephron loop I Surrounded by vasa recta I Descending loop water rushes out bc I Ascending loop active transport of ions Tubular secretion 0 Antiport involved H plays important role in acidbase balance 0 Peritubular capillaries secrete hormonesionsetc in exchange for Na Water conservation 111414 Excretion 3 Juxtamedullary nephrons v cortical nephrons Only need a few juxtamedullary nephrons to assist with functions of collecting duct Osmolarity of urine in collecting duct is 12x to 12x blood osmolarity Reabsorption at Proximal Convoluted Tubule NaK pump pushes Na out of cell amp K into cell in tissue uid between capillary amp tubule epithelium O KCl symport follow Na out of cells into capillary Higher salt concentration drives water toward capillary I solvent drag pulls salts from tubular uid to tissue uid through tight junction Aquaporins embedded in epithelial membrane to bring water through endocellular route Na gradient also used in symport with glucose NaK pump sets up gradients that facilitate movement of materials from tubular uid I tubule epithelial cells I tissue uid I peritubular capillary 0 only thing using ATP directly AcidBase Balance in PCT 0 More acidbase regulation occurs in kidneys than in lungs C02 in lungs V H in kidneys O NaH antiport brings Na into cell amp disposes of H O Bicarbonate buffer system transfers H through renal tubule cells directly these cells are special because of this PCT reabsorbed Glucose amino acids proteins vitamins lactate some ureauric acid Nephron Loop 0 Ion exchange drives water reabsorption by osmosis H20 Conservation Vasa recta capillary loop Ions are transported out of ascending nephron loop gt drives water reabsorption in descending nephron loop amp collecting duct absorbed by vasa recta NaKCl are selectively moved out of tubules I creates countercurrent exchange amp countercurrent multiplier O Concentrate ions in gradient outside tubule higher osmolarity deep in medulla drives water toward high salt water out of tubule 0 More salt added outside of PCT I more H20 can leave through ports in descending loop 0 Ions can ow out through ports in ascending loop 0 Keep surrounding tissue saltier than tubule to continue driving water out Regulation in Distal Convoluted Tubule Vasa recta loop has selective ow in descending vs ascending limb to absorb water Without too much salt Kidney Regulation Renal Plexus O regulate vasoconstriction innervation of individual lobes amp nephrons O restrict blood ow in response for rising BP I important to maintain high filtration pressure Without causing ruptures amp aneurisms Autoregulation O Macula densa top of nephron loop swell in response to high osmolarity ions in uid I release ATP on basilar surface Mesangial cells convert ATP to adenosine Granular cells modified smooth muscle stimulated by adenosine I contract Afferent arteriole constricts Reduced osmolarity amp filtration rate 0000 Systemic Regulation Renin stored in granular cells I Sympathetic nervous stimulation 111714 Hormonal Regulation of Kidneys Tubuloglomerular feedback sensory cells at top of nephron loop macula densa swell in response to higher osmolarity to in uence mesangial cells that trigger granular cells to constrict afferent arteriole to decrease blood pressure Myogenic Mechanism Granular cells contain enzyme renin 0 Can be secreted into bloodstream in response to sympathetic signal when BP drops 0 Baroreceptors I brain I reticular formation I signal to secrete renin Renin breaks up angiotensinogen into short fragments of angiotensin I 0 In lungs angiotensinconverting enzyme ACE angiotensin I converted to angiotensin II active hormone I Hypothalamus triggers thirst I Blood vessels systemic vasoconstriction reduces total volume of arterial O division of circulatory system I Adrenal cortex secretion of aldosterone to act on kidneys Na amp H20 retention Aldosterone O Increases retention of Na and reduces retention of K O Leads to increased osmolarity in tissue H20 retention increased by osmosis as water follows salt into tissue Antidiuretic Hormone Vasopressin O Operates independently of aldosterone and renin 0 Released by posterior pituitary in response to action potential from hypothalamus 0 Triggers increased expression of aguagorins in epithelial cells to allow H20 to ow intracellularly amp be recovered 0 Can occur independently of Na reabsorption Why is it important to drink water Lack of water leads to 0 lower blood pH 0 Less H able to be moved out through nephrons 0 Higher osmolarity on both sides of tubules I precipitation kidney stones Digestive System Enteric Nervous System Innervates digestive track lumen of digestive track is outside relative to body Oral Cavity predigest food before it gets to the stomach chemical mechanically break down food Teeth Can expose food to chemical enzymes before it reaches the stomach Structure varies based on types of food consumed Dentin amp cementum can regenerate but enamel doesn t Fluoride can help to remineralize enamel Deciduous teeth vs permanent teeth I Teeth get replaced as mouth grows larger l Wisdom teeth act as backup bc humans would lose teeth as we got older I Teeth would move such that they move close together over time Salivary Glands O Parotid submandibular and sublingual glands are extrinsic 0 Intrinsic glands are spread across the mouth 0 Seroas cells take uid from blood amp acinus cells add mucin uid binder amp OOOOO lysozyme digests bacteria and lipase amp amylase amp mucous glands O Mumps attacks extrinsic salivary glands Swallowing Oral phase 0 Tongue forms food bolus and pushes into laryngeopharynx Pharyngeal phase 0 Nasal passage blocked by soft palate and trachea blocked by epiglottis O Bolus pushed into esophagus Esophageal phase 0 Peristalsis drives bolus downward 111914 Motility in Digestive Tract Segmentation spaced out contractions Peristalsis Tissue Layers of Digestive Tract Lumen Mucosa epithelia amp small layer of muscle muscularis mucosae O Mucosa associated lymphatic tissue MALT WBCs adjacent to lumen O Beneficial amp nonbeneficial bacteria in intestinal tract only good if in intestinal tract l WBCs help kill any cells that try to cross into body Submucosa contains glands Muscularis extema controls contractions of digestive tract Enteric nervous system MVenteric plexus in inner layer of muscularis externa Submucosal plexus in submucosa Parasympathetic innervation also helps control enteric system Regulates digestive tract semiindependently of CNS OOOO Enteric Nervous System Up to 100 million neurons more than spinal cord Myenteric plexus O In the muscularis layer 0 Regulates peristalsis projects to submucosal plexus O Regulates glands of mucosa Submucosal plexus O Receives signals from myenteric plexus to regulate mucosal glands Discord between enteric nervous system amp CNS implicated in health problems 0 Irritable bowel syndrome 0 May contribute to diabetes amp obesity lack of sense of fullness O Gluten sensitivity Stomach Tight junctions between epithelial cells of epithelial layer protect from HCl Lots of mucus forms a barrier between chyme and cells Cells are replaced every few days Regions 0 Defined by glandular pits in wall of region 0 Cardiac amp Pyloric gland secrete mucus and hormones l Lots of mucus cells 0 Gastric gland secrete HCl and digestive enzymes l Lots of chief and parietal cells All digestion is essentially enzymeassisted throleis Parietal cells produce HCl Chief Cells secrete pepsinogen enzyme precursor O Becomes pepsin as HCl breaks off portion amp activates it 0 Catalyzes hydrolysis of proteins Intrinsic factor glycoprotein binds to vitamin BIZ vital for DNA synthesis amp aminofatty acid synthesis 0 Vitamin BIZ only get it from bacteria 0 Hydrophilic would not diffuse across membranes of cells well Parietal Cells Absorb C02 from bloodstream I makes H2CO3 Dissociates to H and HCO3 Antiport uses ATP to move H into stomach and K into cell Cl pushed into stomach maintains electrostatic balance amp drives bicarbonate dumping into bloodstream forward Alkaline tide 0 Waste HCO3 pushed into bloodstream as H secreted into stomach Stomach Control Hypothalamus amp medulla stimulate stomach Cephalic phase vagus nerve stimulates secretion before food is swallowed Gastric Phase 0 Some paracrine signaling occurs gastric glands release histamine and gastrin encourage secretion of HCl intrinsic factors Intestinal Phase 0 Inhibits gastric secretion with Secretin and CCK O Sympathetic fibers suppress gastric activity amp inhibited parasympathetic O Allows time for reabsorption amp neutralization Duodenum Pancreas amp H NaHC03 released in pancreatic juices to neutralize acid 0 Gives off C02 Pancreas also releases digestive enzymes Liver Produces bile that is stored in gallbladder O Produces steroid hormones phospholipids and fat emulsifiers Receives nutrientrich blood from small intestine via hepatic portal vein Small Intestine Bile salts help to emulsify and break down fat Villi and microvilli increase functional surface area across which absorption can occur 112114 Digestion 3 Bicarbonate Buffer System In RBCs In stomach parietal cells In respiratory tissue In renal tubules Liver amp Gallbladder Bile contains steroids phospholipids etc Hepatic portal vein 0 Large gland that is specialized for absorptionsecretion O Hepatic lobules present in large numbers consist of central vein surrounded by hepatic sinusoids I Blood passes through channels surrounded by W paired with fenestrated epithelial cells 0 Hepatic macrophages catch any bacteria from digestive tract or worn out red blood cells 0 Hepatocytes have microvilli Blood liver handles is mostly arterial some from small intestine Absorbing and processing nutrients coming from digestive tract Carbohydrate metabolism 0 Produce glucose glycogen and adipose tissue Nitrogenous wastes 0 Remove NH2 from glutamic acid carrier amp produce m to allow for excretion Produce nonessential amino acids 0 Then produce plasma proteins amp Vitamin D3 I calcidiol 0 Store Vitamin A and B 12 essential Regulation of Iron levels Excrete excess blood Calcium into bile Dispose of drugs toxins amp hormones Produce bile acids to allow for absorption of fats Digestion and Absorption Hydrophobic exclusion forms fat globules amp makes it hard to absorb fats bc hydrophilic ends stick out Bile salts have hydrophobic amp hydrophilic ends 0 Form small globules of fats amp surround hydrophilic heads with hydrophobic parts to allow micelles to pass into intestinal cells Fats get absorbed in lacteals and pushed through lymphatic system into subclavian vein Sugars amino acids nucleotide absorption 0 NaK pump creates a Na gradient in lumen which then drives glucose amino acids nucleotides etc through Na symports O Glucose amp galactose use Na symport fructose diffuses across membrane Vitamin B 12 is moved via receptormediated endocvtosis H20 glucose Ca2 pass through tight junctions by solvent drag Large Intestine Transports water by transporting ions Habitat for gut micro biome that can remove additional nutrients from food If there is too much salt in food water can t be moved out osmotic diarrhea O Cholera pushes ions into intestinal tract amp water follows 112414 Reproductive System Sex Determination SRY gene activates TDF I activate genes for androgen receptors on X chromosome begins masculinization of fetus Male can express female phenotypes because lack of androgen pathway Testosterone converted by aromatase into estradiol 0 In males less is converted to estrogen SRY amp TDF lead to generation of primary sex organs Anisogamy Differences in gamete size differences in parental investment in individual gametes differences in resources donated Lower parental investment high levels of sexual activity biased operational sex ratio looking for mates more often I competition for mates I more mates higher fitness Higher parental investment lower levels of sexual activity biased operational sex ratio I selection among mates I better mate quality high quality fitness Malebiased operational sex ratio males looking for and competing for mates Meiosis Diploid cell I temporarily tetraploid I 2 diploid daughter cells I 4 haploid gametes Spermatogenesis Germinal epithelium makes up walls of seminiferous tubules Primordial germ cells migrate to gonads in week 56 I differentiate into spermatogonia Produce type B spermatogonia that migrate up seams of sustentacular cells that form exterior of seminiferous tubules 0 Tight junctions form bloodtestes barrier to prevent immune system from killing gametes that are genetically distinct from somatic cells Spermiogenesis Development of agellum Growth of acrosome enzymatic cap that allows to enter egg Develop midpiece of tail packed with mitochondria Shed lots of excess cytoplasm Sperm stored in epididymus for up to 40 days up to 400 million per day Oogenesis Oogonia produced during fetal development produce 67 million Just before birth activated into primary oocytes 2 dozen primary oocytes activated to complete meiosis I each month Half of DNA discarded in polar body while secondary oocyte gains plasma amp organelles 0 Complete on day of ovulation Layer of granulosa cells surrounds oocyte follicle Zona pellucida glycoprotein sheet surrounds oocyte to keep it isolated from other cells LH helps convert cholesterols into androgens I converted to estrogen in follicle Ovarian Cycle Estradiol increases significantly before ovulation l follicle becomes dominant follicle upregulates FSH and LH hormone receptors Fluid builds up in antrum of ovary and helps to push oocyte out 0 WBCs help to weaken wall to release follicle Menstrual Cycle Ruptured follicle creates corpus luteum 0 Secretes lots of estradiol and progesterone to inhibit LH and FSH to prevent release of oocytes Internal mucosa lining of uterus has been growing to prepare for pregnancy If fertilization occurs corpus luteum stays active to prevent endometrium degeneration 12114 Mortality during childbirth for both mother and infant is extremely high in humans relative to other mammals 0 Due to narrower pelvis that helps with bipedalism Average birth weight is 685 pounds 0 Mortality is very high at extremes Mother gains about 3 times weight of fetus 0 Nearly every organ system in mother changes to accommodate birth 0 Only requires about 300 kCal per day additional intake 0 Nearly 6 pounds of weight gain is blood amp tissue uid Ruptured follicle becomes Corpus luteum and secretes lots of progesterone and estrogen 0 If fertilization occurs suppresses shedding of swollen endometrium Hormones during Pregnancy During pregnancy estradiol amp progesterone levels are orders of magnitude larger than during normal cycle Human chorionic gonadotropin stimulates growth of corpus luteum I encourages growth of placenta O Helps suppress LH and FSH release from pituitary Hormones help soften pelvis to allow stretching Fertilization Release of Ca2 ions helps sperm to agellate faster the longer they are in the tract Acrosomal reaction enzymes wear down granulosa cells that surround egg until 1 sperm makes it to egg membrane Once one sperm penetrates egg 0 Fast block membrane is depolarized repels sperm 0 Slow block smooth ER inside egg release Ca2 and cause release of cortical granules into extracellular space I Contain enzymes that will lyse proteins and create hard protein barrier around egg I Glycosoaminoglycans swell with water to form a jelly barrier that thickens and prevents sperm from approaching egg Meiosis II amp Migration Egg completes meiosis II 2 nuclei form mitotic spindle and fuse into diploid set of chromosomes Over next several days cells divide without increase in size I moralla formation Blastocyst forms and implants around day 6 Implantation trophoblast cells fuse and grow into endometrium I encourage endometrium to grow around blastocyst trophoblast becomes charion 0 all tissues associated with fetus that is not part of the fetus 0 takes over secretion of estradiol amp progesterone for the first two months uternine milk and lacuna provide nutrition for growing offspring Embryogenesis gastrulation endoderm mesoderm and ectoderm formed Prenatal Sexual Development SR Y gene turns gonadal regions into testes in absence I becomes female In males epimesonephric duct becomes reproductive tract In females perimesonephric duct becomes reproductive tract External genitalia develop from the same tissue First Trimester weeks 012 By week 8 organ systems are basically established 0 Embryo I fetus Lots of things that can go wrong 0 Transition to placental nutrition systems 0 Roughly 1520 of pregnancies end in miscarriage due to these potential issues Nondisjunction O Vast majority of fetuses with chromosomal abnormalities are miscarried 0 Most chromosomes are relatively large and pretty important for development 0 Chromosomes 13 18 21 and XY are smallest amp have slightly less detrimental effects survivable 0 More likely to occur with increasing age of mother esp if 1st pregnancy Second Trimester week 1324 Placenta stores material for future use when fetal needs outstrip mother s ability to provide energy Chorionic villi of placenta bathed in blood of mother 0 Allows substances to diffuse down concentration gradients 0 Antibodies travel to baby from mother Most organ systems developed by week 24 just growing significantly Fetal v Neonatal circulation O 3 shunts in fetal circulation to avoid redundancy 0 Ductus venousus mostly bypasses developing liver since mother is cleaning blood 0 Ductus arertiosus mostly bypassing blood ow to lungs of fetus mostly collapsed blood ows into aorta instead 0 F oramen ovale lets blood pass from right atrium to left atrium of heart again helps bypass lungs As baby takes first breath pressure change leads to momentary reversal of blood ow closes foramen ovale to allow for normal blood ow Third Trimester week 2537 Most organ systems except brain lungs heart and kidneys are fully developed during 3rd trimester Fourth Trimester Adjustment after most traumatic experience of life birth 12314 Postnatal Development Born relatively underdeveloped because of smaller pelvic cavity Positive Feedback Theory of Labor Stretching of the cervix due to pressure from fetus triggers release of oxytocin by posterior pituitary release lots of hormone extremely quickly I stimulates uterine contractions Part of a larger negative feedback loop First 5 Minutes of Life Blood that was shunted away from lungs by ductus ateriosus and foramen ovale Increased C02 levels due to loss of gas transfer through placenta due to labor force first breath Babies breathe at close to 45 breaths per minute until heart and lungs become more developed In ation of alveoli in first few minutes of life 0 Also results in bypass arteries shriveling to form ligaments Postnatal Nutrition Colostrum first liquid produced by mother different from milk 0 Lots of immunoglobulin A provides antibodies for baby I Provides about 6 months of protection Human milk is crucial for first few weeks 0 Contains lots of lactose and fats to help with heat production 0 Contains bacteria to colonize the gut Feeding babies whole milk for first 2 years helps provide fat for myelination of neurons Ossi cation through Adolescence As we age in uenced heavily by use Senescence Loss of function in organs and organ systems Occurs in sensory systems first especially in ear 0 Lose ability to hear high frequency sounds 0 Loss of exibility or inner ear bones increase in bone density damage to hair cells Presbyopia 0 Loss of exibility of lens to accommodate to shortrange vision Endocrine system 0 Adaptive testosterone is essentially a poison O grandmother hypothesis l Older nonreproducing women can help to raise grandchildren I Act as a living repository of information to convey wisdom to others Integumentary system 0 Collagen cells melanocytes etc lose functionality 0 UV light can increase weathering of integumentary system 0 UV exposure over life leads to decreased ability to synthesize vitamin D Exercise 0 Cardiovascular senescence is most common cause of human mortality
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