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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
Adrenergic Receptors
-bind to norepinephrine and epinephrine -sympathetic postganglionic neuron
26
Alpha Receptors
-both have higher affinity for norepinephrine over epinephrine
27
Beta Receptors
28
Alpha 1 (a1) Receptors
-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
Alpha 2 (a2) Receptors
-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
Secondary Messengers
-transfer the signal from the cell surface into the cytoplasm -influences metabolic processes and thus cellular function
31
cAMP
cyclic adenosine mono phosphate
32
Beta 1 (b1) Receptors
-equal affinity for norepinephrine and epinephrine -cAMP second messenger system -excitatory -usually increased heart rate
33
Beta 2 (b2) Receptors
-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
Beta 3 (b3) Receptors
-higher affinity for norepinephrine -cAMP -excitatory -less common compared to b1 and b2 -break down adipose tissue for energy (brown fat)
35
comparison charts of sympathetic and parasympathetic ns....
36
Antagonistic Effect
37
Complementary Effect
38
Co-operative Effect
39
Somatic Nervous System
-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
Motor Neurons
-axon terminals release Ach -brings about excitation and contraction -can only stimulate, not inhibit
41
Higher centres involved in somatic control
-spinal cord -motor cortex -cerebellum -basal nuclei -brain stem
42
Neuromuscular Junction (NMJ)
-linkage of motor neurons and skeletal muscle fibres -aka motor end plate
43
Synapse
-nerve and muscle cell don't directly meet -chemical messenger carries signal across synapse -chemical messenger is a neurotransmitter: acetylcholine
44
Release of Ach
-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
Motor End Plate
-where the receiving channels are -produces a small graded potential called "endplate potential" -this will trigger a full blown action potential
46
why is an EPP larger than an EPSP
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
Removal of Ach from the synapse
-done by acetylcholinesterase enzyme (inactivates Ach) -Ach removal ends the EPP, relaxing the muscle cell
48
Sustained muscle contraction
-another motor neuron action potential leads to the release of more Ach, keeping the contractile process going
49
Reuptake of Ach to the terminal
-Acetylcholine is broken down into a)choline: reusable b)acetic acid: not reusable, removed from the muscle
50
Vulnerability of the NMJ
-several chemical agents and diseases affect the NMJ -can alter Ach release
51
Black Widow Spider Venom
-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
Botulinum Toxin
-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
Curare
-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
Organophosphates
-chemicals that inhibit AChE so it can't remove ACh -respiratory failure cause diaphragm can't repolarize
55
Myasthenia Gravis
-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
Polio
-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
ALS/Lou Gehrig's Disease
-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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