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94 Cards in this Set
- Front
- Back
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Organization of the Nervous System |
Central Nervous System Peripheral Nervous System |
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Central Nervous System |
Integrates and issues information a: brain b: spinal cord |
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Peripheral Nervous System |
a: Afferent Division (sends information to CNS) b: Efferent Division (receives informationfrom CNS) |
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Efferent Division |
(1) Somatic nervous system (2) Autonomic nervous system a: sympathetic nervous system b: parasympathetics nervous system |
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Three Classes of neurons |
a: afferent neurons b: efferent neurons c: interneurons |
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Afferent neurons |
have sensory receptors axonterminals in CNS send information to CNS from body |
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Efferent neurons |
cell body in CNS axonterminals in effect organ send information from CNS to body |
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Interneurons |
lie within CNS some connect afferent neurons and efferent neurons a: integrate peripheral responses and peripheral information some connect other interneurons a: responsible for activity of the "mind" ie thoughts, emotions, motivation 99% of all neurons are interneurons |
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Parts of the Brain |
brain stem cerebellum hypothalamus thalamus cerebrum limbic system neural basis of some human activity |
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brain stem |
critical connecting link between entire brain and spinal cord cardiovascular respiratory digestive control regulation of muscle reflexes: equilibrium and posture reception and integration of spinal cord input; arousal and activation of cerebral cortex sleep/wake cycle control cerebellum |
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cerebellum |
maintenance of balance enhancement of muscle tone coordination of voluntary muscle activity |
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hypothalamus |
regulation of man homeostatic functions and associated behaviors link between nervous and endocrine systems involved in emotion and basic behavior patterns |
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Regulation of many homeostatic functions and associated behaviors (hypothalamus) |
a: body temperature b: thirst and urine output c: food intake d: uterine contraction and milk production |
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Link between nervous and endocrine systems (hypothalamus) |
smooth and cardiac muscle control exocrine gland control |
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Thalamus |
relay station and filter for all input to cerebral cortex crude awareness of sensation some degree of consciousness role in motor control |
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cerebrum |
basal nuclei cerebral cortex |
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Basal nuclei |
inhibition of muscle tone coordination of slow sustained movement suppression of useless movement pattersns |
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cerebral cortex |
sensory perception voluntary control of movement language personality sonsciousness and sophisticated mental events (thinking, memory, etc) |
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limbic system |
not a separate structure includes inteconnected portions of a: cerebral cortex b: basal nuclei c: thalamus d: hypothalamus involved in generation eotions |
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Neural Basis of some human activities |
movement language and speech emotions memory |
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movement |
requirescomplex interactions among brain stem, cerebellum, thalamus, basal nuclei, and cerebral cortex |
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language and speech |
processed in multipe areas of cerebral cortex |
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emotions |
generated by the limbic system which attaches "feelings" to basic survival related programs of the brainstem including feeding, aggression and sexuality at birth primates have sufficient emotional circuits to bond to a caretaker recognize a face have visual and vocal interaction with caretaker. as a child develops and emotional memories laid down more complex emotions become possible |
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memory |
a: short term memory in frontal lobes of cortex rely on rapid changes in strength of exisiting nerve connections b: long term memory involves limbiv system and requires new connections among neurons; this is accomplished by practice and consolidation |
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Support of the Brain |
Glial Cells a: 90% of cells in CNS are not neurons but are glial cells b: but occupy only 50% of brain volume c: do not initiate or conduct nerve impulses d: support CNS neurons physically metabolically and homeostatically |
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nourishment of the brain and the blood brain barrier |
a: brain carefully shielded from harmful blood changes b: a normal cpillary has proes in its walls for easy passage of materials c: brain capllaries have tight junctions that prevent passage of materials d: only small lipid soluble substances (O2, CO2, alcool, steroid horones) can diffuse through capillary membrae e: all other molecules must be transported into brain by carrier proteins f: a portion of the hypothalamus is not subject to blood brain barrier g: glucose and oxygen |
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brain carefully shielded from harmful blood changes |
prevents changes in blood ions and molecules from adversely affecting brain |
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NOTE: portion of hypothalamus is not subject to blood brain barrier |
monitors blood diretly for levels of hormones etc |
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glucose and oxygen in brain and blood brain barrier |
the brain can only make ATP a: from glucose (no other sugars or fats) b: in presence of O2 hence the brain is dependent on constant supplies of glucose and O2 a: 2-5 min without O2 or 10-15 without glucose=brain damage and then death |
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Spinal cord stucture |
whole cord a: 21 pairs of nerves cross section a: gray matter b: white matter |
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gray matter |
cell bodies dendrites short interneurons glial cells |
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white matter |
mylenated axons organized into tracts (bundles of axons) some are ascending (to brain) and some are desending (from brain) like packaged phone ines |
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spinal cord function |
carries and support neurons (both afferent and efferent) between brain and body simple spinal reflex |
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visceral afferent |
subconscious information sent from the internal viscera to the CNA a: eg concentration of C)2 in the blood (chemoreceptors) b: eg blood pressure (baroreceptors) |
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Sensory afferent |
afferent input that does not reach level of conscious awareness is called sensory information, that is ths pathway a: somatosensory system b: special senses |
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somatosensory system |
body surface sensations a: eg skin muscles joints inner ear limb positon |
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special senses |
vision touch hearing taste smell |
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We can percieve |
sound color shape texture smells tastes temperatue |
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we cant percieve |
magnetic fields (birds can) light polarization (birds can) radio waves xrays |
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human limitations in perception |
we cant hear high frequencies that dogs can some features of stiuli are accented or ignored during precortical processing cerebral coretex fufurther manipulates data to "complete the picture: thus our perceptions do NOt replicate relatity |
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Sensitivity of receptors to stimuli transduction |
a receptor functions by converting stimulus energy to an action portential |
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a receptor is specialized for specific stimuli |
eyes see but do not hear but if you are hit in the eye (hitting is a mechanical stimulus) you "see stars" |
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types of receptors
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photoreceptors-vision thermoreceptors warmth cold mechanoreceptors chemoreceptors nociceptors (pain) |
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mechanoreceptors |
osmoreceptors (ECF osmolarity) baroreceptros (blood pressure) hair cells (sound balance) |
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chemoreceptors |
taste, smell, blood oxygen, blood pH |
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compound sensations |
eg wet=mechano+thermo |
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Two types of receptor structure |
seperate cell produces a receptor potential which is grades potential a: most speical senese are like tis modified ending of afferent neuron produces a generator potential which is a type of graded potential a: olfactory is only speical sense like this |
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when receptor stimulated(either type) reults in |
the non-selective opening og all small ion channels usually results in the net influx of Ca++ and/or Na+ ions which causes a membrane depolarixation this is a grades potential so the bigger the stiulus the bigger the change in portential |
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conversion of receptor and generator potentials into APs |
modified ending of afferent neuron a: local current flow occurs from end of afferent neuron to axon of same afferent neuron b: causes opening of Na- channels c: if threshold is reached in the axon an AP ocurs |
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separate cell |
separate receptor cell stimulated which opens Ca++ channels iflux of Ca+ causes release of chemical messenger messenger binds to protein receptor on membrane of afferent axon causes Na+ channels to open on afferent axon if enough Na+ chhannels open threshld is reached and an AP occurs |
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THE STRONGER THE STIMULUS THE HIGHER FREQUENCY OF AP THAT OCCUR IN AFFERENT NEURON |
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AS MORE RECEPTORS AREACTIVATED MORE APS ARE PRODUCED |
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Adaption of receptors to stimuli |
slow adapting (tonic) receptors a: do not adapt to stimuli b: continue to produce APs as stimuli continue c: eg muscle stretch receptors fast adapting (phasic) receptors a: rapidly adapt to stimuli b: stop producing APs even though stimuli continue c: eg body surface tactile receptors (putting on a shirt no longer aware of it on) |
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fate of informtion transmitted by receptors |
receptor causes AP in afferent neuron (the first order neuron) afferent AP reaching spinal cord either a: becomes part of the reflex arc b: or is relyed toward brain by interneuron (second order neuron) (1) second order neuron synapses with thirs order neuron in the thalamus (2) third order neuron transmitts information to the cerebral cortex where sensory perception ccurs |
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Taste and Smell |
receptors are chemoreceptors a: receptors binds specific chemical and generates neural signal stimulation of taste nd smell receptors can cause "pleasurable" or "objectonable" sensations important in finding fgood food avoiding toxins finding mates |
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Taste buds |
modified epithelial cells 10000 taste buds in mouth mostly tongue ech taste bdud has a single opening consists of about 50 receptor cells a: each receptor has binding sites that selectively bind chemicals b: bidning a chemical causes depolarzation of receptor membrane c: can initiate APs in afferent neurons with whcih they synapse d: taste receptors have lifespan of 10 days |
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sour taste |
causes by acids (H+) H+ blocks K+ channels which reduces K+ leaking out of cells which depolarizes membrane when membrane deploarizes Ca++ channels open and Ca++ enters cell entry of Ca++ causes release of neuotransmitter which bind to taste affrents and can cause AP in taste afferent |
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salty taste |
primarily NaCl Na+ moves through specialzed Na+ channels to depolarize membrane when membrane depolarizes Ca++ channels open and Ca++ enters cell entry of Ca++ causes release of neurotransmitter whic bind to taste afferents and can cause AP in taster afferent |
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sweet taste |
glucose or related sugar bind receptor activates a "G protein" system that ivolves several enzymes ultimately results in blocking K+ channels which reduces K+ leaking out of cell which depolarizes membrane when membrane depolarizes Ca++ channels open and Ca++ enters cell entry of Ca++ causes release of neurotransmitter whch bind to taster afferents and can cause A in taster afferent |
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Bitter taste |
many chemicals can bnd to btter receptors (caffeine, nicotine, morphibe, strychnine) bittter molecule blocks K+ channels which reduces K+ leaking out of cell which depolarizes membrane when membrane depolarizes Ca++ channels open and Ca+ enters cell entry of Ca++ causes release of neurotransmitter |
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Bitter taste buds NOTE |
some bitter taste buds apparently use a G protein system which ultimately vcauses release of neurotransmitter which bind to tster afferents and can cause AP in taster afferent (like sweet) |
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umami |
amino acids especially glutamate bind receptors causes net influx of Na+ which deploarizes membrane and ultimately cause release of neurotransmitter which bind to taster afferents and can cause AP in taster afferent |
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Neural pathway for taste |
taste receptor to afferent neuron (first order neuron) to second order neuron in brain stem to third order neuron in thalamus to gustatory corex taste also heavily infuences by smell |
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Olfactory Receptors (smell) |
only speical sense receptor that is modified endings of affernt neurons (instead of separate cell) axons of olfactory receptors collectively from olfactory nerve (branial nerve I) receptor cells constantly replces only neurons known that do this 5 million receptors of 10000 differnt kinds (compared to only 3 receptor types for color vision and 4 for taste) each receptor responds to specific components of odors |
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smell sensations |
receptor binds specific odor chemical cascade of intercellular reactions that open N+ and Ca++ channels can thus generate APs in the afferent axon high frequency of binding= high frequency of APs |
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smell neural pathway |
olfactory neurons (first order neurons) to mitral cells (second order neurons) in olfactory bulb in forebrain to olfactory tubercle (in cerebrum not in thalamus) to olfactory cortex ad to limbic system (both in cerebral cortex) vis third order neuron This is an evolutionary ancient pathway. recently discovered evolutionarily young pathway associated with conscious awareness of smell does seem to utilize that thalamus. |
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Efferent division |
communication link by which the CNS controls activities of effector organs (muscles organs glands etc) |
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efferent division organization |
automatic a: involuntary branch b: two parts (1) symppathetic (activity) (2) parasympathetic (routine housekeeing) somatic a: voluntary branch affects skeetal muscle |
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Structure common in both sympatehtic and parasympathetic |
every pathay in each autonomic pathway consists of a two neuron chain cell body of first neuron lies in the NCS its axon synpases with cell body of 2nd neuron in cain in ganglion axon of 2nd neuron innervates the effector organ |
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structure in sympatehtic only |
orginiates int he thoracic and lumbar regions of spinal cord adrenal medullaa (inner part of adrenal) is modified sympathetic ganglionn a: secretes hormones into blood when stimulated |
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structure parasympathetic only |
origniat in the cranial(brain_ and sacral (pelivc) areas of the CNS |
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sympathetic neurotransmitters |
1st neuron in chain releases acetylcholine 2nd neuron in chain releases norepinephrine adrenal medulla releases mostly epinephrine into blood |
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parasympathetic neurotransmitters |
1st neuron in chain releases acetylcholine 2nd neuro in chain releases acetylcholine |
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Release onto effector organs |
sypathetic releases norepinephrine and epinephrine while parasymahetic releases acetylcholine |
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reponse of effector organs to sympathetic and parasympathetics |
depedns on effector organ and its receptors as well as neurtransmitter |
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Acetlycholine receptor |
called cholinergic located on 2nd neuron in all autnoic neron chains (called nicotinic receptors) on membrane of effector organs (called muscarinic receptors) |
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nonrepinephrine and epinephrine receptors distributed on effector organs |
alpha: binds norepi preferentially usually ccauses contrsitions;contractions beta-1: bind norepi and epi equally found primarily in the hear causes stimulation of heart beta-2: binds mostly epi usually causes local dilation/relaxation |
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functions of sympathetic and parasympathetic |
most organs are innervated by both sympathetic and parasympathetic systems these tend to act in opposition to each other to give the exact response needed in effector organs. they are like getting temerture in shower just right by adjusting hot and cold knobs |
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exceptions to functions of sym and parasym |
innervated blood vessels receive only sympathetic (except those in penis and clitoris which also have parasympathetic) sweat glands innrvated by symp onlu salivary glands innervated by both bt different kinds of saliva produced by eahch |
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sympathetic and parasympathetic tonic activity |
both system active at low levels |
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shifts in balance between sympathetic and parasympathetic |
can be accomplished idscretely for individual organs to meet specific demands |
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One system can dominate body wide for a massive repsonse |
usually occur when sympathetic dominates in fight or flight situation. |
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Sympathetic dominates |
blood vessels to ost organs constrcted=reduced blood flow to digestive orgas (cause by alpha receptors binding norepi) blood vessels to heart dilated (causes by beta02 receptors binding epi) increased heart rate and increased force of contraction of whole heart (causes by beta-1 receptors binding epi and norepu) blood vessels to skeletal mulce dilated (causes by beta-2 receptors binding epi) airways in lung dialted (causes by beta-2 receptors binding epi) glucose released (caused by beta-2 receptors in lover binding epi) |
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parasympathetic dominated |
in quiet siutation invoved in regulating normal housekeeping functions (digestion) |
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Erections |
the penis contains spongy tissue derived from beins and cppilaries during secual arousal flls with blood; increased pressure closes off veins that drain blood from penis=vassocongestion=erecton erection controlled by spinal reflex between highly senstive mechannoreceptors in the penis and the erection generation center in the spinal cord refferent response is parasypathetic which leads to vasodiliation of blood vessels which leads to vascocongestion=erection in ways that are not well understood various regions in brain can either enhance or tard erection reflex |
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emission of sperm from testis |
when stimulation becomes intense the pesnid spinal reflex described aboveswitched to a sympathetic efferent responde that causes muscle in penis and testes to contract to emit sperm and seminal fluids into urethra |
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explusion of sperm from penis |
urethra filling with semen triggers sympathetic respond that activated muscle at the base of the penis and muscle in the penis rythmic contraction of these muscles at 0.8 second intervals increases pressure inside penis which then forcibly expels semen=orgasm refractory period follows male orgasm; no erection possible; seems to be caused by release of hormone called prolactin from pituitary lgland |
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human female sexual cycle |
sexual stimuli trigger spinal reflexes that cause para induced vasodilation of blood vessels in vagina and clitoris clitoris is composed of spongy vasuclar tissue and becomes erect brain can enhance or retard sexual spinal reflex vascocongestion of vagina causes release of lubricating secretions which allow smooth entry of penis vascocongstion of vagina causes release of lubricating secretions which allow smooth entry of penis vascocongestion also occurs in breasts (englarging them and face become flushed from increased blood flow in skin furhter vascogonestion of vagina reduces its inner circumference uteris raises upwards lifting cervix creating a space for ejaculated depositon if stmulation continues sympathetic induced rythiic contracions of pelic muscles especially lower 1/2 of vaginal canal at 0.8 second intervals =orgasm no refactory period=multiple orgasms possible |
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somatic nervous system |
motor nerons innervate sketal muscle they constitute the somatic ervous system |
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structure of motor neurons |
cell bodies are in ventral orn of the spinal cord axon of motor neuron is continuous from psinal cord to termination in skeltal muscle axon terminals release acetylcholine (ach) |
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control of motor neuron function |
arch releae cause excitation and contracion of the muscle can only stimulate skeltal muscle control and level of activity exereted by relative balance of EPSP and IPSP from excitatory and inhibitory presynaptic inputs thus the somatic nervous sytem is more of an "on-off" system ompared to the autonomic nervous system which is a dual control system some inputs are part of spinal-reflex pathways others are part of descendigng pathways from parts of brain (especially mortor regions of cortex, basal nuclei, cerebellum, and brain stem) somatic nervous system is condiered "vluntary" but much of skeltal activity is subconscious (posture, balance, walking) |
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neuromuscular junctions structure |
motor neurons had long mylinated axon part of azxon nar muscle divides into many axon terminals whicg are unmylinated each axon terminal forms a neuromuscual junction with one of mnay muscle cells (muslce cell is also called a muscle ifiber) muscle diber is long and clylindrical axon terminal has knob at end called terminal button terminal button fits into groove in muscle fiber but dos not toch muscle fiber part of muscle fiber under terminal button is called motor end plate |
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neuromuscular junctions function |
Motor neuron action potential (AP) reaches terminal button Triggers opening of Ca++ channels; Ca++ enters terminal button Ca++ triggers release of acetylcholine from terminal button Acetylcholine diffuses across gap and binds receptors on membrane of motor end plate Binding of Ach results in opening of cation channels; result: lots of Na+ enters musclecell, a little K+ leaves cell, membrane depolarizes Entry of Na+ results in end plate potential, which is a graded potential., and is called anend plate potential (EPP). Local current flow leads to AP in membrane of muscle fibernext to motor end plate; AP goes in both directions. Ach is destroyed by acetylcholinesterase, terminating the muscle cell response. |
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NOTE neurmuscular junction function |
unlike synaptic tranmission in which single EPSP is not enough to cause AP the magnitude of EPP is nearly always sufficient to cause an AP in the muscle fiber. Also no inhibitory responses at a neuromuscular junction (inhibition occurs att eh presynnaptic inputs of motor neuron |
