Upgrade to remove ads
VPHY 3100 - EXAM 2 (Ch.9: ANS)
Terms in this set (38)
How many nerves exit the brain? How many exit the spinal cord? What are they composed of?
12 pairs of cranial nerves; 31 pairs of spinal nerves
**most nerves are mixed - comprised of both sensory and motor fibers
What are the categories of the Peripheral Nervous System? Explain what they are and any subgroups.
1) Autonomic (controls interval activities - organs and glands) : contains the sympathetic (arousing) and parasympathetic (calming) divisions
2) Somatic (controls external actions of skin and muscles)
Explain the characteristics of the autonomic motor system. (e.g. - effector organs, presence of ganglia, # of neurons from CNS to effector, type of neuromuscular junction, effect of nerve impulse on muscle, type of nerve fibers?)
1) Effector organs - cardiac muscle, smooth muscle, glands
2) Cell bodies of post ganglionic autonomic fibers located in paravertebral, prevertebral (collateral), and terminal ganglia
3) Two neurons from CNS to effector
4) Neuromuscular junction - no specialization of postsynaptic membrane; all areas of smooth muscle cells contain receptor proteins for NTs
5) Effect - either excitatory or inhibitory
6) Slow-conducting; preganglionic fibers lightly myelinated/thin and postganglionic gibers unmyelinated and very thin
Explain the characteristic of the somatic motor system. (e.g. - effector organs, presence of ganglia, # of neurons from CNS to effector, type of neuromuscular junction, effect of nerve impulse on muscle, type of nerve fiber?)
1) Skeletal muscles
2) No ganglia
3) One neuron from CNS to effector
4) Neuromuscular junction - specialized motor end plate
5) Effect - excitatory only
6) Fast-conducting, thick, and myelinated
What's the different between preganglionic neurons and postganglionic neurons?
Preganglionic - cell body lies in the gray matter of the brain/SC
Postganglionic - 2nd neuron that will innervate the target tissue
Give examples of how the autonomic motor system contrasts with the somatic motor system.
-Efferent neurons: AMS is different from SMS because it has two tandem neurons that go to target tissue; AMS has preganglionic neurons that connect at the autonomic ganglion which then connects to the postganglionic neuron (innverates target tissue)
-Central control: hypothalamus, brain stem, spinal cord (autonomic); frontal cortex, subcortical structures (somatic)
Compare and contrast the sympathetic and parasympathetic divisions.
-Both: consist of preganglionic neurons (in CNS) and postganglionic neurons (in PNS)
-Differs: origination of preganglionic fibers, location of autonomic ganglia, NT used (to some extent), functions (parasympathetic = "rest & digest"; sympathetic = "fight or flight)
*also parasympathetic division does not have a chain of ganglia against spinal cord like sympathetic
Name the types of autonomic ganglia and which division they are associated with. Give the general location.
Sympathetic: paravertebral ganglia (closer to spine), collateral (prevertebral) ganglia (farther out from spine)
Parasympathetic: terminal ganglia (close to target tissue; at times can be inserted in target tissue)
Name the function of the parasympathetic and sympathetic divisions
parasympathetic = "rest & digest"; sympathetic = "fight or flight
What is the function of the dorsal root? Ventral root?
Dorsal root - sensory information (PNS --> CNS)
Ventral root - motor output (efferent) (specifically, motor output side of sympathetic division)
Name some examples of the effects on the body of the sympathetic and parasympathetic divisions. (pupil constriction, salivation, heart rate, digestion, intestinal/rectal movement)
Sympathetic: pupil constriction (decreases), salivation (decreases), heart rate (increases), digestion (decreases), intestinal/rectal movement (decreases)
Parasympathetic: pupil constriction (increases), salivation (increases), airway constriction (increases), heart rate (decreases), digestion (increases), intestinal/rectal movement (increases)
When the preganglionic axons of the sympathetic motor division reaches the paravertebral ganglia, what happens?
3 different things can occur:
1) preganglionic fibers can synapse on postganglionic neurons within the sympathetic chain of ganglion and rejoin the spinal nerves via gray rami
2) preganglionic fibers can pass through sympathetic chain of ganglia, forming splanchnic nerves, which synapse on postganglionic neurons within prevertebral ganglia
3) preganglionic fibers can innervate the adrenal medulla, which secretes Epi/Norepi into blood
How does preganglionic axons make its way to the paravertebral ganglia of the sympathetic motor division?
Via white rami
Explain the process at which information is transferred among the parasympathetic motor division. Be sure to mention the origin.
1) Preganglionic fibers originate in midbrain, medulla, pons, and sacral levels of SC
2) Preganglionic fibers synapse with postganglionic fibers in the terminal ganglia (lie close to or within target organs)
The sympathetic system is typically activated as a single unit
Which division innervates cutaneous effectors and blood vessels associated with skeletal muscles?
*parasympathetic fibers are not bonded within spinal nerves and therefore doesn't regulate this
What is the function of the Vagus nerves? Where do they originate?
Primary route of parasympathetic innervation - carry preganglionic parasympathetic fibers to terminal ganglia (heart, lungs, esophagus, stomach, pancreas, liver, intestines); originates in the medulla
What did Otto Loewi discover?
Chemical transmission between neurotransmitters: "the vagus substance" - stimulated vagus nerve for one heart (heart rate slowed) ---> heart 2 then received the inhibitory effect of vagus
What does SAME DAVE stand for?
Sensory Afferent Motor Efferent
Dorsal Afferent Ventral Efferent
What is the NT that is released from the preganglionic fibers of BOTH divisions?
Acetyl choline (cholinergic)
What is the NT that is released from the postganglionic fibers of the sympathetic division?
-Mostly norepinephrine, or (nor)adrenergic
-Some postgang. fibers are cholinergic: release acetyl choline (those to blood vessels of skeletal muscles and those to sweat glands)
What is the NT that is released from the postganglionic fibers of the parasympathetic division?
-Most are cholinergic (release acetyl choline)
When is the receptor type on the target tissue for preganglionic fibers?
nAChR (nicotinic acetyl choline receptors): LGIC = excitatory
What is the receptor type on the target tissue for the parasympathetic postganglionic fibers?
mAChR (muscarinic acetyl choline receptors): GPCR = inhibitory/excitatory
**remember the G protein is heterotrimeric
What does the response of the target tissues depend on?
Although the same NT is used at times, different effects can occur (inhibitory/excitatory); this is due to the different types of receptor proteins on the target tissues
What is the receptor type on the target tissue for the sympathetic postganglionic fiber?
α1, α2, β1, β2 - adrenergic receptors (always act via G-proteins): can be excitatory/inhibitory
**some fibers that run with spinal nerves are cholinergic
Which specific types of receptors of the sympathetic postganglionic fibers create an EPSP? What is the specific affect?
(EPSP = contraction/constriction, or vesicle release)
β1 - increase cardiac output
α1 - vasoconstriction at some viscera
Which specific types of receptors of the sympathetic postganglionic fibers create an IPSP? What is the specific affect?
(IPSP = relaxation, dilation)
β2 - relaxation of bronchioles, vasodilation at some viscera,
β2 and some muscarinic - vasodilation at skeletal muscles
Explain how the sympathetic adrenergic receptors work (in general). What activities occurs due to them?
G-protein coupled receptors:
Gαβ𝛾 --> Gα + Gβ𝛾
-Sometimes modulation of ion channel permeability
-Mostly modulation of enzyme activity (-->(indirectly) changes in ion channel permeability)
Describe the mechanism of action for β1 and β2 receptor
activation --> increases [cAMP]i
--> smooth muscle relation (bronchioles; vasodilation)
--> increased heart rate
*Detailed: Norepi binds to receptor --> conformational change in β1 --> activated associated G protein --> alpha subunit (activated) interacts with downstream effector (adenylate cyclase) --> converts ATP to cAMP --> cAMP binds to kinase --> phosphorylates downstream effectors (= Ca2+ channels) = increased HR
Describe the mechanism of action of the α1 receptor
α1 receptor activation --> increases [Ca2+]I --> smooth muscle contraction --> vasoconstriction of certain viscera
The postganglionic parasympathetic fibers release Ach. Effects depend on the muscarinic receptor subtype. List the receptors and what happens during activation.
M3, M5 activation --> opening of Ca channels --> increased [Ca]i --> depolarization/contraction of smooth muscles or increased gland secretions
M2 activation --> slows heart rate (via vagus)
Describe the mechanism of action for the vagal innervation of the heart via M2 receptors.
Parasympathetic cholinergic innervation via vagus --> M2 type muscarinic receptors --> indirectly opens K+ channels --> hyper polarization of heart muscle cells --> slowing of heart rate
Describe the difference between nAChR's and mAChR's. What effects do they cause?
nAChRs - postsynaptic membrane of: all autonomic ganglia, all neuromuscular junctions, some CNS pathways; LGIC; causes excitation
mAChRs - produces parasympathetic nerve effects in the heart, smooth muscles, and glands; GPCR; M2 = inhibition, M3/M5 = excitation
How are most visceral organs innervated by the autonomic system?
Dually-innervated: antagonist (most common), complementary (similar effects), cooperative (synergistic effects)
Which organs are ONLY sympathetically innervated?
Adrenal medulla, arrector pili muscles (skin), sweat glands (skin), most blood vessels
What is considered the command system for autonomic and endocrine systems?
What is the control center for cardiovascular, digestive, urinary, and reproductive systems?
You might also like...
Chapter 9 Physiology: The Autonomic Nervous System
The Autonomic Nervous System
Chapter 14: Autonomic Nervous System
Chapter 11: Efferent Division: Autonomic…
Other sets by this creator
PSYC 5850 - Quiz 4
PSYC 5980 Quiz 3
PSYC 5850: Quiz 2
Ecology Exam 1