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HLSC 126 - Human Physiology I > Chapter 5B > Flashcards

Chapter 5B Flashcards

1
Q

The Peripheral Nervous System (PNS): Efferent division

A

-part of the nervous system that lies outside the brain and spinal cord
-sends commands away from brain to the periphery
-Efferent division consists of 2 subdivisions: autonomic and somatic

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2
Q

Autonomic Innervations

A

-cardiac muscle
-smooth muscle
-most exocrine glands
-some endocrine glands
-adipose tissue

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3
Q

Autonomic Nervous System (ANS)

A

-involuntary
-maintain dynamic equilibrium: homeostasis
-stress response
-reproduction
-thermoregulation
-extends from CNS to an innervated organ

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4
Q

Enteric Nervous System

A

-part of the ANS
-within the GI tract
-influences pancreas, liver, gallbladder (secretion, motility, blood flow)

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5
Q

Hub of the ANS

A

-hypothalamus
-brainstem
-spinal cord

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6
Q

Sympathetic Nervous System

A

-division of the autonomic NS
-flight or flight response
-heart rate increases
-blood pressure increases
-rate and depth of respiration increase
-energy stores are mobilized by working tissues ie. skeletal muscles
-digestion decreases
-redistribution of resources ie. blood flow and O2 delivery to digestive tract restricted
-O2 delivery increased to skeletal muscles, heart, lungs, skin
-glycogen breakdown
-hypothalamus
-secretion of epinephrine, norepinephrine, other hormones are increased

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7
Q

Parasympathetic Nervous System

A

-division of the autonomic NS
-rest and digest response
-heart rate decreases
-muscle use decreases
-digestion increases
-nutrients begin to be stored again

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8
Q

Two Neuron Chain (ANS)

A

-cell body of first neuron is located in the CNS, its axon is the preganglionic fibre which synapses with the cell body of the second neuron
-cell body of second neuron lies in a ganglion, its axon, the postganglionic fibre innervates the effector organ ie. smooth muscle or heart

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9
Q

Ganglion

A

cluster of neuronal cell bodies that lies outside the CNS

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10
Q

Sympathetic Innervation

A

-innervate thoracic and lumbar regions of the spinal cord
-“thoracolumbar”

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11
Q

Sympathetic Preganglionic Neurons

A

-short
-ganglions are paravertebral (para = adjacent to) meaning they lie on either side of the spinal cord
-secrete Acetylcholine (ACh) in the ganglion

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12
Q

Collateral Ganglia

A

-when some preganglionic fibres don’t synapse through the sympathetic ganglion chain
-they end here: between the CNS and innervated organs
-postganglionic fibres travel the rest of the distance

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13
Q

Sympathetic Preganglionic Receptors

A

-cholinergic nicotinic receptors
-in the ganglion

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14
Q

Parasympathetic Innervation

A

-preganglionic fibres arise from the cranial (brain) and sacral (lower spinal cord) areas of the CNS
-“craniosacral”

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15
Q

Parasympathetic Preganglionic Neurons

A

-longer than sympathetic preganglionuc fibres because they don’t end until reaching terminal ganglia (lie in or near effector organ)
-secretes Acetylcholine into the ganglion

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16
Q

Parasympathetic Preganglionic Receptors

A

-cholinergic nitcotinic

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17
Q

Sympathetic Postganglionic Neuron

A

-longer
-goes to target/effector organ
-secretes norepinephrine (20%) or epinephrine (80%) or dopamine (1%)

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18
Q

Sympathetic Postganglionic Receptors

A

-located on the target
-adrenergic; release noradrenaline aka norepinephrine
-alpha (a1 or a2) or beta (b1 b2 or b3)

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19
Q

Parasympathetic Postganglionic Neuron

A

-shorter
-secretes Acetylchloine

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20
Q

Parasympathetic Postganglionic Receptors

A

-on the target
-cholinergic just like all the autonomic preganglionic fibres
-muscanaric; fiver subtypes: _____

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21
Q

Nicotinic

A

-activated by tobacco plant derivative: nicotine
-found on all postganglionic cell bodies in autonomic ganglia
-respond to Ach from preganglionic fibres; open cation channels in postganglionic cell = depolarization and an action potential

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22
Q

Muscanaric

A

-activated by mushroom poison: muscarine
-found on effector cell membranes
-bind with Ach from parasympathetic post ganglionic fibres
-5 subtypes that are linked to G proteins which activate second messenger systems leading to target cell responses

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23
Q

Varicosities

A

-swellings in the terminal branches of postganglionic autonomic fibres
-opposed to single terminal swelling like a synaptic knob

24
Q

Cholinergic Receptors

A

-bind to acetylcholine
-all preganglionic
-only symp. postganglionic

25
Q

Adrenergic Receptors

A

-bind to norepinephrine and epinephrine
-sympathetic postganglionic neuron

26
Q

Alpha Receptors

A

-both have higher affinity for norepinephrine over epinephrine

27
Q

Beta Receptors

A
28
Q

Alpha 1 (a1) Receptors

A

-use calcium second messenger system
-most tissues
-usually an excitatory response in effector organ
-present in most sympathetic target tissues
-ie. salivary glands, ejaculation, bladder

29
Q

Alpha 2 (a2) Receptors

A

-uses cAMP
-inhibitory
-found in smooth muscles of the GI tract
-relaxation
-insulin decreases
-binding of a NT to a2 blocks cAMP production in target cell
-break down fat molecules

30
Q

Secondary Messengers

A

-transfer the signal from the cell surface into the cytoplasm
-influences metabolic processes and thus cellular function

31
Q

cAMP

A

cyclic adenosine mono phosphate

32
Q

Beta 1 (b1) Receptors

A

-equal affinity for norepinephrine and epinephrine
-cAMP second messenger system
-excitatory
-usually increased heart rate

33
Q

Beta 2 (b2) Receptors

A

-greater affinity for epinephrine over norepinephrine
-cAMP second messenger system
-generally inhibitory response
-flattening of ocular lens for far vision
-smooth muscles of respiratory tract
-vasodilation
-liver; make glucose available for breakdown

34
Q

Beta 3 (b3) Receptors

A

-higher affinity for norepinephrine
-cAMP
-excitatory
-less common compared to b1 and b2
-break down adipose tissue for energy (brown fat)

35
Q

comparison charts of sympathetic and parasympathetic ns….

A
36
Q

Antagonistic Effect

A
37
Q

Complementary Effect

A
38
Q

Co-operative Effect

A
39
Q

Somatic Nervous System

A

-motor neurons innervate skeletal muscle
-1 neuron system; continuous from CNS to ending on skeletal muscle
-cell bodies within ventral horn of spinal cord (except for those that supply head are in brain stem)
-mostly voluntary control
-posture, balance, stereotypical movements are subconsciously controlled

40
Q

Motor Neurons

A

-axon terminals release Ach
-brings about excitation and contraction
-can only stimulate, not inhibit

41
Q

Higher centres involved in somatic control

A

-spinal cord
-motor cortex
-cerebellum
-basal nuclei
-brain stem

42
Q

Neuromuscular Junction (NMJ)

A

-linkage of motor neurons and skeletal muscle fibres
-aka motor end plate

43
Q

Synapse

A

-nerve and muscle cell don’t directly meet
-chemical messenger carries signal across synapse
-chemical messenger is a neurotransmitter: acetylcholine

44
Q

Release of Ach

A

-action potential propogation triggers opening of voltage gated Ca2+ channels in terminal button
-diffusion of Ca2+ triggers release of Ach by exocytosis from vesicles

45
Q

Motor End Plate

A

-where the receiving channels are
-produces a small graded potential called “endplate potential”
-this will trigger a full blown action potential

46
Q

why is an EPP larger than an EPSP

A
  1. more NTs released from terminal button than presynaptic knob
  2. motor end plate has a larger surface area (more receptor sites)
  3. more ion channels are opened = larger depolarization
47
Q

Removal of Ach from the synapse

A

-done by acetylcholinesterase enzyme (inactivates Ach)
-Ach removal ends the EPP, relaxing the muscle cell

48
Q

Sustained muscle contraction

A

-another motor neuron action potential leads to the release of more Ach, keeping the contractile process going

49
Q

Reuptake of Ach to the terminal

A

-Acetylcholine is broken down into
a)choline: reusable
b)acetic acid: not reusable, removed from the muscle

50
Q

Vulnerability of the NMJ

A

-several chemical agents and diseases affect the NMJ
-can alter Ach release

51
Q

Black Widow Spider Venom

A

-triggers explosive release of Ach from the vesicles at all cholinergic sites (not just NMJ)
-keeps depolarizing NMJ
-leads to respiratory failure and person dies

52
Q

Botulinum Toxin

A

-poison produced by bacterial pathogen: clostredium botulinum
-blocks release of Ach to motor end plate
-prevents muscles from responding to nerve impulses
-flacid paralysis:muscles can’t be excited
-death due to respiratory failure due to inability to contract the diaphragm

53
Q

Curare

A

-blocks action of Ach at receptor sites
-binds to Ach receptor sites
-doesn’t alter membrane permeability, not inactivated by AChE
-paralysis ensues
-deadly arrowhead poison
-person dies from respiratory failure

54
Q

Organophosphates

A

-chemicals that inhibit AChE so it can’t remove ACh
-respiratory failure cause diaphragm can’t repolarize

55
Q

Myasthenia Gravis

A

-inactivates ACh receptor sites on motor end plate
-immune system attacks receptor sites
-autoimmune disorder: body attacks itself
-drooping eyelids
-difficulty chewing/walking
-not genetic

56
Q

Polio

A

-caused by poliovirus
-starts with contaminated food or H2O
-attacks somatic NS
-grows in cell body of motor neuron which leads to cell death
-results in paralysis

57
Q

ALS/Lou Gehrig’s Disease

A

-neurofilaments block axonal transport of crucial materials
-extracellular accumulation of toxic levels of excitatory NT glutamate
-aggregation of misfolded intracellular proteins
-mitochondrial dysfunction leading to reduced energy productiion

HLSC 126 - Human Physiology I (5 decks)

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