Exam 3 Study Guide
Exam 3 Study Guide BSCI 201
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This 9 page Study Guide was uploaded by Brooke Sullivan on Sunday May 1, 2016. The Study Guide belongs to BSCI 201 at University of Maryland taught by Dr. Meredith Bohannon in Spring 2016. Since its upload, it has received 297 views. For similar materials see Human Anatomy and Physiology in Biological Sciences at University of Maryland.
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Date Created: 05/01/16
Lecture 17 • Two types of neuroglia in the PNS - Satellite cells: surround cell body of neuron - Schwann cells: form myelin sheath of neurons in PNS • Two types of axonal transport - Anterograde: away from the cell body; moves mitochondria, cytoskeletal proteins, components of plasma membrane, neurotransmitters; motor protein kinesin - Retrograde: toward cell body; recyclable organelles, substances that deliver info about the axon terminal; motor protein dynein • Ions and RMP - More sodium outside of cell and more potassium inside of cell - K+ is 25 times more permeable than Na+ - The K+ leaky channels allow for the flow of K+ ion into the cell, but because there are so few Na+ channels, there is an accumulation of positive ions outside of the cell, creating a relatively negative charge on the interior of the cell. • Graded vs Action Potential - Graded: in dendrites and cell bodies, short distance, decaying, chemical or sensory stimulus for propagation - Action: in axons, long distance, no decay, voltage channels for propagation • Changes in Polarity of Neuron - Depolarization: more positive MP, closer to threshold - Hyperpolarization: more negative MP after resting - Repolarization: more negative MP after depolarization • Myelination and AP Velocity - Bare plasma membrane: voltage decays - Voltage channels but no myelin: conduction is slow and AP must continuously regenerate (continuous conduction ) - Myelination and voltage channels: fewer leaky channels and AP can regenerate less often so conduction is fast (salutatory conduction) • Speed of an Action Potential - Axon diameter - Degree of myelination • Stimulus Strength and Action Potentials - Stronger stimulus creates greater frequency of Aps • Excitatory and Inhibitory Potentials - Excitatory (EPSPs): depolarization, can summate - Inhibitory (IPSPs): hyperpolarization, no summation - Temporal summation: 2 stimuli close in time that make EPSPs come together - Spatial summation: 2 stimuli at the same time but in different places that make EPSPs come together - Spatial summation of EPSPs and IPSPs: the cancel each other out • Synaptic Potentiation: - Potentiation: potentiation that occurs over a long period of time - Depression: EPSPs happen less frequently or in smaller magnitude over time, making an action potential less likely - This demonstrates plasticity because instead of creating new neurons for new memories, the brain makes new pathways with existing neurons • Neurotransmitters - Excitatory: depolarize - Inhibitory: hyperpolarize - Direct: bind and open ion channels - Indirect: activate second messenger system; binds to receptor, activates G protein, activates adenylate cyclase; ATP converts to cAMP; opens ion channels - Biogenic Amines: emotional behavior and circadian rhythms; imbalances cause mental issues (low epinephrine can cause depression); psychoactive drugs make problems (LSD decreases serotonin activity) - GABA: inhibitory; if inhibited, convulsions will occur - Glutamate: excitatory; when blood vessels are blocked, there are lower levels of oxygen in the brain which leads to the excessive release of glutamate in the brain, eventually causing a stroke - Peptides: pain mediation - Adenosine: caffeine blocks its receptors, suppressing its inhibitory affects, which leads to increased blood pressure Lecture 18 • Neurulation - The process of the neural tube being forms from embryonic folding • Grey and White Matter - Gray matter: neuron cell bodies and short nonmyelinated neurons - White matter: most of it is myelinated axons, while some is nonmyelinated axons • Ventricles - Cavities in the brain that are continuous with one another • The Cerebrum - Motor, sensory and association areas - Pyramidal cells, which comprise the corticospinal tracts • Broca’s Area - Left side of the brain - Involved with speech production - Understanding of body language and emotional context of tone of voice - Damage to the Broca’s area that results in speech impairment - He left hemisphere of the brain is better at language skills, so damage to it severely limits language function • Olfactory Cortex - Olfactory perception, because the olfactory cortex is loca ted in the limbic system, is closely related to emotions and memories - Ex: smelling cookies and remembering your grandmothers house • Prefrontal Cortex - Complex learning decision making, and working memory - He became more mean and was no longer good at complex tasks • Cerebral Cortex Body Maps - Primary motor area in precentral gyrus and primary somatosensory area in postcentral gyrus - Face, tongue, and hands; Face, lips and fingertips • Nerve Fibers That Comprise Cerebral White Matter - Association: within one hemisphere - Commissural: between to hemispheres - Projection: from low CNS to cortex and back • Basal Nuclei - Increase and decrease strength of movements that stem from the primary motor cortex - Also involved in cognitive function, motivation, and emotion - Parkinson’s: Direct pathway is inhibited while indirect is over stimulates so there is a slowing in movement over time - Huntington’s: relationship not stated but there is an increase in uncontrolled movement over time • Thalamus - Reticular activating system • Hypothalamus - Controls ANS, perception of pleasure, fear, and rage, bio rhythms, body temp, hunger and satiety, thirst, and thyroid, gonads, and adrenal glands - Limbic system • Epithalamus - Melatonin: induces sleep • Brain Stem - Corticospinal tracts - Pyramidal tracts - They are the same cells - Decussation: fibers of the pyramidal tracts cross over and that is why there is lateralization of the brain • Cerebellar Processing 1. Cortex sends message to cerebellum with desired movement 2. Cerebellum scopes out the environment and picks up any sensory information 3. Cerebellum calculates the movement 4. Cerebellum sends a message back to the cortex with directions on how to execute the movement • Cerebrospinal Fluid - Less protein and different concentrations of ions - It must first make it through the choroid plexus, then it is filtered through the ependymal cells • The Spinal Cord - White matter is located in the columns while gray matter is located in the horns - Nerve rootlets, then dorsal and ventral roots Lecture 19 • Reticular Formation - Passes through the brain stem - Connects to the cerebral cortex - RAS sends sensory input to cortex - Filters out unimportant signals so that you can focus on what is important • Memory - Excitement, rehearsal, association with new data • Consciousness and Sleep - Alpha waves: calm wakefulness; Beta: mentally alert; Theta: concentration (in adults); Delta: deep sleep, or brain damage in awake adults - Perceive senses, move voluntarily, carry out higher mental functions - Alert, then drowsy, then asleep, then stupor, then coma - A coma is complete unconsciousness while sleep, on the other hand, is partial unconsciousness - REM: dreaming occurs; NREM1, NREM2, NREM3, NREM4: sleep walking occurs - During night terrors, the brain is asleep while the body becomes active. Sleepwalking, talking and crying may occur. During sleep paralysis, the body is asleep while the brain wakes up. • Ascending and Descending Tracts - 3 in ascending, 2 in descending • Injuries of the CNS - Concussion: brain is bruised, dizziness, becoming unconscious, coma - Stroke: clot causes low blood supply to the brain, depriving it of oxygen, releasing too much glutamate that kills nearby cells - Hemorrhage: damage to blood vessels in the brain Lecture 20 • Sensory Receptors - Stimulus type: mechano, photo, thermo, chemo, noci - Location: extero, intero, proprio - Structure: non-encapsulated and encapsulated • Sensory Integration - Sensation: what your body senses and the information it send to the brain about its environment - Perception: how your brain integrates and interprets the sensory information - Receptors must be for the specific stimuli, stimuli must be converted into a graded potential, graded potentials must reach threshold • Nerves - Vagus nerve: extends out of cranium and beyond the neck, contains both motor and sensory nerves - Rootlets, then dorsal and ventral roots, then merge and diverge into dorsal and ventral rami - Ventral rami form nerve plexuses and recombine to form nerves - Cranial: neck and parts of shoulder; brachial: arms, parts of shoulder; lumbar: lower limbs and parts of abdominal wall; sacral: lower limbs, genitalia, perineum, butt • Reflexes 1. Tap patellar ligament and excite muscle spindles of quadriceps 2. Afferent nerves send signal to spinal cord 3. Motor neurons send signal to quadriceps to contract 4. Interneurons inhibit synapses with ventral horn neurons, inhibiting the resistance of contraction Lecture 25 • Ganglia Location - In the sympathetic, the ganglia are closer to the CNS, and in the parasympathetic, ganglia are closer to the effector organs • Purpose - Sympathetic: fight or flight - Parasympathetic: rest and digest • Effects - Sympathetic: mobilizes energy stores and turns off unnecessary functions - Parasympathetic: keeps body energy use low and is involved with basic maintenance • Dual Innervation - Both systems will innervate the same tissue or organ, but one will be excitatory while the other is inhibitory • Receptors - Cholinergic: bond acetyl choline, in ganglia are called nicotinic, on effector cells called muscarinic - Adrenergic: bind epinephrine and norepinephrine, only in sympathetic, alpha 1 constricts blood vessels and inhibits production of mucus, beta 1 increases heart rate, beta 2 dilates blood vessels and airways in lungs, b3 stimulates lipolysis • Drugs and Chemicals - Nicotine agonists: nicotine, sympathetic effects - Muscarinic agonists: bethanechol, parasympathetic effects - Muscarinic antagonsts: atropine, blocks muscarinic receptors - Acetylcholinesterase inhibitors: sarin, keeps Ach around for more time - Sympathetic agonists: albuterol, binds to adrenergic receptors - Sympathetic antagonists: beta blockers, block adrenergic receptors Lecture 22 • Photoreceptors - Rods: perceive light and work better in dim light - Cones: perceive color and work better in bright light • Retinal and opsin - Bind together to form rhodopsin, a photopigment found in the rods - In the dark, retinal takes on its trans shape, and in the light it takes on its cis shape • Transduction of Light - When light strikes the eye, it is absorbed by rhodopsi n, making retinal change to its cis shape. When it does this, it dissociates with the opsin. This activates a second messenger system that hyperpolarizes the photoreceptor. The photoreceptor stops releasing inhibitory NT to the bipolar cells, and they are able to release NT into the ganglion cells, producing an action potential. In the dark, there is no light to dissociate rhodopsin, so the photoreceptors are depolarized and they release their inhibitory NT to the bipolar cells. The bipolar cells do not release their NT, so no APs are sent to the brain. • Smell - Odorant receptors on the olfactory cilia (chemoreceptors) - 400 receptors combine to sense over 1 trillion smells - There are also pain and temperature receptors in the nose (ammonia, capsaicin, menthol) • Taste - Taste receptors in taste buds (chemoreceptor) - Sweet: sugar - Salty: metal ions - Sour: acid - Bitter: caffeine - Umami: MSG • Hearing and Balance - Semicircular canals: hair cells in cristae ampullares; rotational acceleration; respond to mechanical stimulation (rotation of body); stimulated by movement of endolymph; found in ampullary cupula; vestibular nerve - Vestibules: hair cells in maculae; linear acceleration; respond to mechanical stimulation; stimulated by movement of otolith membrane; found under otoliths and otolith membrane; vestibular nerve - Cochlea: hair cells on spiral organ; hearing; respond to mechanical stimulation (waves); stimulated by movement of inner ear fluid; found on top of basilar membrane; cochlear nerve - All use variations of hair like cells as receptors - The outer hair cells amplify vibrations of the basilar membrane, but stiffen during noises that are too loud to protect the inner cells from damage - Sound into the ear canal, vibrates tympanic membrane; vibrates auditory ossicles; vibrations travel through oval window and vibrate inner ear fluid; basilar membrane vibrates, vibrating inner hair cells; AP is sent through the cochlear nerve - The higher the frequency, the closer to the oval window on the spiral organ the wave hits. The lower the frequency, the farther away on the spiral organ.
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