Anatomy and Physiology I
Anatomy and Physiology I Anatomy and Physiology
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This 15 page Study Guide was uploaded by Lyndsey Wenzel on Tuesday February 23, 2016. The Study Guide belongs to Anatomy and Physiology at West Chester University of Pennsylvania taught by Giovanni Cassotti in Spring 2016. Since its upload, it has received 38 views. For similar materials see Science in Science at West Chester University of Pennsylvania.
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Date Created: 02/23/16
1. Can you describe the characteristics of a motor unit? Motor Unit Single motor neuron and all of the muscle fibers it innervates Basic unit of skeletal muscle contraction Smallest unit of skeletal muscle contraction Size o Low innervation ratio- few fibers per motor neuron, eye muscles, more control, no power o High innervation ratio- many fibers per motor neuron, gross movements, leg/ quad 2. What’s the difference between isotonic and isometric contractions? Can they be combined? Isotonic- same force, muscle fibers shorten depending on strength of force Isomeric- same length, do not shorten Yes they can happen together Mechanical response of muscle fibers- muscle twitch 3. What are the different types of stimuluses’? Nerve electrode- nervous impulse arrives at muscle fiber, brain to fiber Muscle electrode- cell to cell Muscle lever- response on muscle fiber, brief contraction/ twitch all or none response threshold- minimum stimulant strength suprathreshold-above subthreshold- below 4. What’s the difference between cellular level contraction and organ level contraction? Cellular level contraction Organ level contraction Contraction of whole muscles Variation is based on recruitment of motor units, strength of contraction based on # of motor units Recruitmet takes place in the CNS- increase # of fibers 5. What are the different types of sustained contraction? Twitch fusion- stimulus arrives before initial twitch is completed, increase/regulate duration by overlapping twitches Single twitch Partial twitch fusion- Summation- increase force Patical twitch fusion- incomplete tetanus- partial relaxation, max force Complete twitch fusion, no relaxation, complete tetanus Tonus- controlling contraction of each motor units, some contract while others rest 6. Where does the energy required to produce ATP come from? 3 phosphate Contraction requires ATP -limited stores of ATP -must synthesize ATP as fast as it is used up RELAX- ATP, 3 phosphates, high energy CONTRACT-ADP 2 phosphates, low energy ATP resynthesis- phosphocreatine, most common to generate ATP in skeletal muscle Oxidation of Carbon: ADP+PCr ATP + Cr ADP takes phosphate from PCr so ATP is made and creatine is left Oxidation of glucose –ultimate creation of ATP 7. What’s the difference between red fibers and white fibers? Muscle made of mixture of red and white fibers Red fibers- slow twitch, oxidative Take longer to contract, rely on oxidation of glucose for energy, have lots of mitochondria White fibers- fast twitch, powerful, glycolytic Contract quickly and use more energy, less mitochondria bc of different pathway, glycolytic energy Proportions of red/white fibers determined by muscle function and genetics White speed and power, sprinters Red duration, long distance Everyone born with different proportions, athletes have unusually high proportions 8. Can you describe the structure of a sarcomere? Basic unit of contraction, extends from z line to z line a. What is the difference between thin filaments and thick filaments? Thin filaments- I band, actin, regulatory proteins Actin monomer- binding sites- part of actin that interacts with myosin Actin polymer- rotation- lets binding site face all directions Regulatory proteins- regulate turning contraction on and off o Tropomyosin- on top of binding sites o Troponin- interacts with Ca2+ ions. Calcium chemical trigger for contraction, exposes binding sites Thick- A band, myosin Myosin polymer o Bundle of stalks- half head cocked, half head rotated Myosin monomer o Head interacts with actin of binding sites, this attachment is called CROSSBRIDGE o Cocked rotated = high energy low energy 9. Describe the sequence of mechanism of contraction. What happens at each step? Resting State No myosin actin binding Tropomyosin blocking binding sites on actin Calcium stored in sarcoplasmic reticulum All myosin head are in cocked position, want to connect to actin but no Ca Stimulation: Initiation of contraction Neural action potential arrives at muscle fiber Muscle fiber conducts action potential Sarcoplasmic reticulum releases Ca Ca binds to troponin Expose Binding Sites Binding of calcium to troponin causes a conformational change in troponin-tropomyosin complex Tropomyosin rotates, thereby exposying binding sites on actin Nerve runs to t tubule, allows calcium released from lateral sacs and binds to troponin Crossbridge formation Once binding sites on actin are exposed, myosin heads automatically bind to actin As heads rotate to center to form crossbridge, become a lower energy state Power Stroke(translation) Once myosin binds to actin, myosin head automatically rotates Rotation pulls actin filaments toward the center of the sarcomere Low energy state prefers ATP over actin High energy state prefers actin over ATP Release crossbridges Following rotation, myosin heads release actin and bind to ATP Recock myosin heads ATP bound to myosin splits to ADP + P Energy is used to recock the myosin head Myosin is now ready to bind to actin Cycle (bind-rotate-release-recock) repeats itself as long as ATP is available and the binding sites remain exposed Relaxation Calcium pumped back into sarcoplasmic reticulum, requires active transport In the absence of calcium, tropomyosin rotates back into the position to block binding sites Sarcomere relaxes back to the resting state 10. What are the four major muscle groups? What are their embryonic derivitives? Gut Muscles Splanchinic mesoderm o Smooth muscle 2 layers o inner circular layer o outer longitudinal layer Trunk Muscles myotomes o striated muscle o come from somatic mesoderm 2 major divisions o dorsal- epaxial muscle mass (extensors) medial deep, short muscles of the back move individual vertebrae, fine tune movement of vertebrae, when contract lateral long muscles of the back extend the vertebral column when contract act along entire length o ventral- hypaxial muscle mass (flexors), dorsal and ventral dorsal part- back prevertebral muscles flex vertebral column bend vertebral coluµn laterally ventral part thoracic muscles- extend between ribs o internal intercostals o external intercostals o move ribs during breathing o sheets of muscles run opposite direction, opposite functions abdominal muscles o internal oblique o external oblique o transverse abdominus-run horizontally rectus abdominus o pelvic rectus=long straight muscle; flex trunk o abdominal pressure increased during vomit, child birth head muscles o extrinsic eye muscles lateral, medial ,superior, inferior rectus superior and inferior oblique o toungue muscles hyoglossus- hyoid to tounge styloglossus- styloid process to tounge genio glossus- chin to tounge Limb Muscles- from ectoderm mesenchyme o striated muscles 2 muscle masses o dorsal muscle mass dorsal extensors- back arm o triceps brachii- extends forearm o extensors in forearm- extends hand and fingers leg o quadriceps femoris- extends lower leg o extensors inlower leg- dorsi flex foot o ventral muscle mass- front ventral flexors arm o biceps crachii and brachialis- flex forearm o flexors in forearm- flex hand and finger leg o hamstrings- flex lower leg o flexors in lower leg- plantar flex foot girdle o dorsal extensors deltoids- extends arm gluteal muscles- extends leg o ventral flexors pectoral muscles- flex arm thing adductors- flx leg *don’t forget potential problem Branchial Muscles brancial arches o branchial refers to throat o gills in embryo o around gut tube splanchnic mesoderm o only place gives rise to skeletal muscle, not smooth specific muscles o larynx(voicebox) & pharynx (deep part of throat) o muscles that move the jaw masseter temporalis pterygoid o muscles of facial expression o sternocleidomastoid o trapezeus 11. What are the main functions of the nervous system? Function and Organization Function Sensory o input Motor o output Body Region Somatic o Somites, somatic mesoderm, ectoderm Visceral o Splanchnic mesoderm, endoderm Function X Body Region o Somatic Sensory- any sensation from skin, senses, vision, hearing, proprioreception o Somatic Motor- output going going to region of body, muscle o Visceral Sensory- from gut, hunger, nausea o Visceral Motor- all glandular secretion 12. What are the different types of neurons? How does this play a part in the reflex arc? Neurons- collect and distribute information, does the job of the nervous system, transmits info to another cell, neuron, or fiber Structure o Cell body o Cell processes o Dendrites o axon Conduction o stimulus o nerve impulse- action potential o only want neuron to conduct action potential when there is a presence of information Synapse o neurotransmitter- chemical released in synapse, presence of this chemical acts as stimulus to second cell Reflex Arc- simplest neuro pathway o Minimum Requirements o stimulus- info, inititate process o receptor o effector- ability to generate response o neuron- pathway, simplest neural circuit o 3 Neuron Pathway o sensory neuron- interpret info detect presence of info o association neuron- determine what to do with info functions- gives varied behavioral complexities, varies responses locations brain spinal cord o motor neuron- used to perform function 13. What is the difference between sympathetic and parasympathetic? Nervous System o CNS o Brain o Spinal cord o PNS o Afferent- sensory Somatic sensory Visceral sensory o Efferent- motor Somatic motor Visceral motor Autonomic o Pasasympathetic- resting o Sympathetic- activity fight or flight response 14. What are the two basic types of cells in the nervous system? Neurons- functional cells in nervous system, process info, send info point A-B Supporting cells- support neurons, help do their job in processing info but don’t do anything directly Origins o Neural Tube o Epithelial cells, rise to ependymal cells spinal cord o Neural Crests- cells migrate anywhere o Mesenchyme- become sensory neurons 15. Can you describe the different parts of a neuron? Cell Body- large, easy to spot in tissue o Large nucleus o Nissl Substance- ribosomes and rough ER in cell body, produce lots of proteins and neurotransmitters o Neurofibrils- bundles of filaments give support to processes of cell body Cell processes o motor neurons o dendrites- short, represent input site, feed info into neuron, multi polar neurons- multiple places to input info o axon- only one, info comes out, as long as necessary to take info to destination, conducts action potential axon hillock- where action potentials originate telodendria-branches terminal boutons- knob on end of branch, forms synapse with next neuron o sensory neurons- uni polar- single cell process o peripheral processes info towards cell, longer process o central processes info flows away from cell, shorter process Nerve Fibers vs Nerves o nerves are a bundle of nerve fibers that contain connective vascular tissue o nerves fibers- part of nerve cell, long process of neuron o nerves- organs Synapses- interaction of terminal boutons and dendrite o typical structure o axon terminal bouton- where info exits o synaptic cleft- small space between cells where neurotransmitters are released o dendrite- where info goes into o variations o axon- axon o axon- body o axon- dendrite o axon- shat o directionality- synapse determines where info goes 16. What makes up the CNS? The PNS? Cell body groupings o CNS o Nuclei- collection of cell bodies in the brain o Horns or coumns- collection of cell bodies in the spinal cord o PNS o Ganglia- collection of cell bodies in PNS Dorsal root ganglia- cell bodies for sensory neurons Ganglia of autonomic nervous system- cell bodies further from roots Supporting Cells groupings o CNS o Neuroglia- all supporting cells in CNS Astrocytes- surround blood vessels, contribute to blood/brain barrier, extra filter Microglia- phagocytic cells, bacteria, dead cells, garbage collector Oligodendrocytes(myelin)- cell wraps around fibers to form myelin sheet (protein) Ependymal cells- neural epithelial cells found @ boundries, facing central canal of nervous system, line the central canal, give rise to all cells of CNS o PNS o Satellite cells- form protective capsule around ganglia o Schwann Cells (myelin)- produce myelin sheet 17. What does Myelin do? Myelin- ensures that cells move quickly and correctly from one nerve cel to another o Lipo protein sheath o Nodes of ranvier- exposed regions of myelinated nerve fiber o Saltation o Myelated- jumping or leaping from node of ranvier to node of ranvier, most fibers are myelinated o Unmyelated- continuous conduction o Speed of conduction- velocity action potential can travel along fiber o High velocity- myelinated, increase temperaure to increase velocity 18. What are the different types of connective tissue in a neuron? Nerves Neurons o Fasicles- bundles of fibers to make up a nerve o Contain neurons, vascular and connective tissue so its an organ Blood Vessels Connective Tissue o Endoneurium- around individual fibers, act as insulator, smallest o Perineurium- tissue around each fasicle o Epineurium- tissue around bundle of fasicles/nerve 19. What are the characteristics of Action Potential? Action Potential- membrane potential caused by distribution of ions response to information o Nervous Impulse o Stilmulus- any change in the environment of cell capable of causing a response o Oscilloscope- measures time vs voltage; membrane potential Resting Membrane Potential o -70mV bc membrane potential of cell o characteristic of all living cells at resting state o no muscle contraction Electrical changes in Vm with stimulus o preliminaries o muscle o oscilliscope 0 mv o all points outside cell are isoelectric to eachother Weak Stimulus o subthreshold o no muscle contraction o oscilloscope -70mv and moves to -50mv when two second stimulus applied Strong Stimulus o threshold or suprathreshold action potential muscle contraction! o increase strength of stimulus, twitch response 20. How is it used as a mechanism for conveying information? (Including steps of depolarization, repolarization, etc.) Mv increase, rise in graph depolarizing membrane Mv decrease, decline in graph repolarizing membrane Action Potential o Resting membrane potential-Polarized bc of its difference in charge o Stimulus- depolarization o Depolarization: influx in Na sodium o If hits threshold sodium channels open o Sodium floods to interior due to concentration ad electrical gradient o At peak: Na+ closes and K+ potassium opens o Repolarization: efflux of K+ potassium o K+ leaves cell to turn voltage back to resting value o Resting membrane potential restored: K+ closes o Na+/K+ pump: reset chemical gradients o Active transport to reset concentration gradient Characteristics of action potential o Requires threshold stimulus o All or none response o Brief duration o Refractory period- time waited between action potentials, during this time action potentials cannot respond to stimulus o Occupies a discrete region on the membrane o Impulse must be transmitted along the membrane o TRANSMISSION of action potential- domino effect, NA/K pump 21. What are the different types of neural receptors? Neural Receptors- sensory neurons, receptors respond to presence of stimuli and changes in environment of cell and receptor itself o Classification o Type of stimulus Mechanical- touch Thermal- changes in temperature Chemical- changes in chemical environment, fluids Electromagnetic- changes in light, visual info o Body location Exteroreceptors- outside body, surface Enteroreceptors- located deep, gathers info inside o Response to stimulus o Generator potential- membrane potential Depolarization of the receptor membrane- shift in distribution of ions bringing more positive ions to inside 22. What are the characteristics of Generator Potential? Generator Potential o Characteristics o Localized ( not propagated or transmitted)- cant be sent to CNS, stays in receptor Must be capable of evoking action potentials in the peripheral process of the sensory neuron o Response is graded according to stimulus strength Stronger the stimulus, greater generator potential, greater depolarization Not all or none o GP is maintained for as long as the stimulus is present The longer the stimulus is present, the longer the generator potential is maintained 23. How are Action Potentials coded? Coding for stimulus quality o Type of receptor o Vision, hearing, smel, taste, touch Coding for stimulus location o Location of receptor Coding for stimulus strength o Frequency of APs o Low GP= low frequency of action potentials o High GP= high frequency of action potentials o Number of receptors stimulated Coding for duration of stimulus o Duration of GP- if stimulus is present, continue receiving APs 24. What are the steps involved in a synapse? SYNAPSE o Structure- detailed explanation above, specialized transfer of info cell to cell o AP arrives at presynaptic terminal and dies out o AP arrival causes membrane to become permeable to Ca2+; Ca2+ enters presynaptic terminal o Only thing action potentials do when arrive at synapse are open Calcium channels o Ca2+ causes neurotransmitter to be released from synaptic vesicles into synaptic cleft o Acetylcholine- neurotransmitter, exocytosis o Neurotransmitter diffuses across synaptic cleft and binds to NA+ channels on post synaptic membrane o Acetylcholine finds binding sites on postsynaptic membrane o Bound neurotransmitter(acetylcholine) opens sodium channels is postsynaptic membrane; NA+ enters post synaptic terminal o Bring NA inside, depolarize membrane o Postsynaptic membrane depolarizes o Postsynaptic potential- PSP o Localized, cannot be transmitted o How much depolarization depends on Na+ , depends on open channels, depends on neurotransmitters, depends on Ca2+, depends on action potential o If the post synaptic potential reaches threshold it is an Excititory PSP and it generates APs in the postsynaptic neuron o Inhibitory postsynaptic potential IPSP- prevents info from crossing synapse o Aps continue until neurotransmitter I removed by enzymes on postsynaptic membrane o Acetlycholinesterase- enzyme that degrades acetylcholine o Acetlycholinesterase degrades neurotransmitter into choline and acetic acid o Choline is reabsorbed bby presynaptic terminal and recycled to make more acetylcholinesterase 25. How do local Anesthetics work? Actions of local anesthetics- anesthetics interfere with formation of membrane potentials o Receptor vs nerve fiber o Receptor: GP doesn’t even pick up stimulus o Nerve fiber: AP stops signal from reaching brain **more common!!! o Temporary vs reversible 26. What is Convergence? Convergence- more than one presynaptic neuron synapses with a single post synaptic neuron, stronger with twitch/contraction happens together o Structural organization o Facilitation o One possible outcome of convergence, increased response o Inhibition o Inhibitory neurotransmitter released with twitch, no response 27. What are the different types of agents that affect synaptic transmission? Paralysis- prevent synapse from being turned on o Block release of neurotransmitter o Magnesium, concetration rises 2x prevents calcium channels from opening o Block binding of neurotransmitter o Curare- binds to bnding sites on post synaptic membrane, occupies site but doesn’t open channels so others cannot bind, no enzyme to get it off death o Use up neurotransmitter o Fatigue Overactivity- prevent synapse from being turned off o Inhibit acetylcholinesterase o Insecticides and nerve gas o convulsions
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