Lecture 15 Somatic Motor & ANS Flashcards Preview

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Flashcards in Lecture 15 Somatic Motor & ANS Deck (24)
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1
Q

Somatic motor effectors

A

skeletal muscles

efferent division of the PNS

2
Q

Autonomic effectors

A

cardiac muscle, smooth muscle, glands, adipose tissue

3
Q

Somatic motor division

A

somatic motor neurons activate skeletal muscles

voluntary (mostly): control of movement posture, breathing

4
Q

Somatic Motor Pathway

A

one motor neuron pathway from CNS to muscle(effector)
motor neuron cell bodies located in the ventral gray horn of spinal cord
axons travel through spinal nerves
axon terminals located at the neuromuscular junction

5
Q

3 components of the neuromuscular junction

A

axon terminal of motor neuron
synaptic cleft
motor end plate

6
Q

neuromuscular junction

A

ACh into the synaptic cleft
nicotinic cholinergic receptors at the motor end plate
binding of ACh open cations channels -> strong EPSP->
exceeds threshold -> muscle AP

7
Q

Autonomic Division (ANS)

A

involuntary control of autonomic effectors (visceral organs, blood vessels, etc.)
activated by the hypothalamus, pons&medulla, and spinal cord (autonomic reflexes)
two motor neuron pathway from CNS to effectors: preganglionic and postgagnlionic

8
Q

Autonomic division ganglionic fibers

A

preganglionic fibers from CNS to autonomic ganglia

postganglionic fibers from autonomic ganglion to target organ

9
Q

2 Divisions of the ANS

A

sympathetic - fight or flight

parasympathetic- rest and digest

10
Q

Dual innervation of sympathetic and parasympathetic

A

to target organs, usually antagonistic (opposite)
both systems are active, but parasympathetic dominates during normal maintenance states; sympathetic system dominates during short term stress, exercise, cold, drop in BP

11
Q

ANS organization

Sympathetic Division

A

thoracolumbar outflow
short preganglionic, long postganglionic fibers
ganglia located in sympathetic chain and collateral ganglia
adrenal medulla is functionally part of the sympathetic division

12
Q

In the sympathetic division what do postganglionic neurons secrete

A

norepinephrine (NE) as the neurotransmitter at target cells

13
Q

Adrenal medulla’s role in the sympathetic division

A

stimulated directly by preganglionic sympathetic fibers
secretes the hormones epinephrine (E) and norepinephrine (NE)
only stimulated by sympathetic response

14
Q

where do the preganglionic fibers in the sympathetic division arise from?

A

the thoracic and lumbar spinal cord

15
Q

Where do the short preganglionic fibers go to in the sympathetic

A

go to sympathetic ganglia close to the spinal cord

16
Q

Parasympathetic division

A

carinosacral outflow (preganglionic arise from cranial and sacral regions)
long preganglionic, short postganglionic fibers
post ganglionic neurons secrete acetylcholine (ACh) as the neurotransmitter at target cells
terminal ganglia located in or near target organs

17
Q

Vagus nerbe (cranial nerve X)

A

is the major parasympathetic nerve to visceral organs

18
Q

ANS neurotransmitter and receptors

preganglionic fibers

A

ACh-> nicotinic cholinergic receptors

sympathetic and parasympathetic

19
Q

Postganglionic fibers

sympathetic

A

E, NE -> adregergic receptors
most target cells use NE as the neurotransmitter
E is the hormone released form the adrenal medulla
alpha-adrenergic receptors
beta-adrenergic receptors

20
Q

alpha-adrenergic receptors

Sympathetic

A

a1 -> constriction of blood vessels

G-protein couples receptors, activate phospholipase C second messenger pathway

21
Q

beta-adrenergic receptors

sympathetic

A

B1-> stimulates heart
B2-> bronchodilation
G protein couple receptors, activate cAMP second messenger pathway

22
Q

postganglionic fibers

parasympathetic

A

ACh-> muscarinic cholinergic receptors

G-protein coupled receptors, open or close K+ channels (excitatory or inhibitory)

23
Q

Sympathetic causes

A

increase heart rate and contractability (B1)
inhibits digestive tract motility and secretion (a, B2)
vasoconstriction in peripheral blood vessels (a, some B2)
vasodilation in skeletal muscles
bronchiole dilation (B2)
pupil dilation (a)
mobilization of energy reserves (glycogen and lipids)

24
Q

Parasympathetic causes

A

decrease in heart rate (no effect on contractility) (B1)
stimulates digestive tract motility and secretion (a,B2)
no effect on blood vessels
bronchiole constriction (B2)
pupil constriction (a)
no metabolic effects