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Flashcards in Intro to PNS Deck (47):
1

Describe pathway of somatic nerves

Single neuron efferent pathway
Directly innervates skeletal muscle

2

Describe pathway of sympathetic nerves

Two neuron efferent pathway (preganglionic and postganglionic)
Preganglionic neuron - short
Postganglionic neuron - long
Ganglia are paravertebral (sympathetic chain) or prevertebral (celiac, s. & i. mesenteric)

3

Describe pathway of parasympathetic nerves

Two neuron efferent pathway (preganglionic and postganglionic)
Preganglionic neuron - long
Postganglionic neuron - short
Ganglia are in/near the structures innervated

4

Where does the sympathetic division originate?

T1-L2 (thoraco-lumbar division)

5

Where does the parasympathetic division originate?

Cranial nerves 3, 7, 9, 10 and sacral (cranio-sacral division)

6

What is the neurotransmitter of somatic nervous system?

ACh

7

What is the preganglionic neurotransmitter of parasympathetic nervous system?

ACh

8

What is the postganglionic neurotransmitter of parasympathetic nervous system?

ACh

9

What is the preganglionic neurotransmitter of sympathetic nervous system?

ACh

10

What is the postganglionic neurotransmitter of sympathetic nervous system?

NE

11

What are the exceptions to postganglionic neurotransmitter of sympathetic nervous system?

Normally NE
ACh - sweat glands
Dopamine - renal vascular smooth muscle

12

Describe synthesis and packaging of ACh

ACh synthesized from choline and acetyl-CoA by choline acetyltransferase (ChAT)
ACh transported into vesicles by H+-coupled countertransporter (VAT)
ACh released (with ATP and cotransmitters) in Calcium dependent process

13

Describe termination of ACh action

ACh rapidly degraded into choline and acetate by AChE
Choline is taken back up and recycled by Na-coupled choline cotransporter

14

Describe synthesis and packaging of NE

Tyrosine transported into nerve terminal by Na-coupled cotransporter
Tyr converted to DOPA by tyrosine hydroxylase (rate limiting step)
DOPA converted to dopamine
Dopamine transported into vesicles by H+-coupled countertransporter (VMAT)
Dopamine converted to NE by dopamine-beta-hydroxylase (DBH)
NE released (with ATP, DBH, and cotransmitters) in Calcium dependent process

15

Describe termination of NE action

NE reuptake into nerve terminal by NET
NE diffuses from the site of action

16

How is epinephrine formed?

NE converted to EPI by phenylethanolamine-N-methyltransferase in the adrenal medulla

17

What are metabolic products of catecholamines?

Normetanephrine and metanephrine
MHPG (MOPEG)
VMA

18

What are the general categories of cholinergic receptors?

Nicotinic
Muscarinic

19

What are the general categories of adrenergic receptors?

Alpha
Beta

20

What type of receptor are nicotinic receptors?

Ionotropic

21

What type of receptor are muscarinic receptors?

G protein coupled receptors

22

What are the types of nicotinic receptors and where are they located?

Nm (neuromuscular junction)
Nn (autonomic ganglia, adrenal medulla)

23

What are the types of muscarinic receptors, where are they located, and which G protein is used?

M1 - autonomic ganglia, Gq
M2 - heart, Gi
M3 - smooth muscle, glands, endothelium, Gq

24

What is the response of M1 activation?

Late EPSP in ganglia

25

What is the response of M2 activation?

Decreased heart rate and contractility, slows spontaneous depolarization

26

What is the response of M3 activation?

Contraction of smooth muscle
Secretion

27

What type of receptor are adrenergic receptors?

G protein coupled receptors

28

What are the types of alpha receptors, where are they located, and which G protein is used?

Alpha1 - smooth muscle in vasculature, Gi and Go
Alpha2 - pancreatic beta cells, platelets, nerve endings, Gi and Go

29

What are the types of beta receptors, where are they located, and which G protein is used?

Beta1 - cardiac muscle, Gs
Beta2 - smooth muscle pulmonary, liver, skeletal muscle, Gs
Beta3 - adipose cells, Gs

30

What is the response of Alpha1 activation?

Vasoconstriction
GU relaxation
Glycogenolysis and gluconeogenesis

31

What is the response of Alpha2 activation?

Decreased transmitter release, causes contraction

32

What is the response of Beta1 activation?

Increased heart rate, force of contraction, and renin release

33

What is the response of Beta2 activation?

Relax smooth muscle
Increase glycogenolysis and K uptake

34

What is the response of Beta3 activation?

Increased lipolysis

35

What is the response of dopaminergic receptor activation by NE?

Relaxation of renal vascular smooth muscle

36

What is the predominant tone of bronchiole smooth muscle?

Parasympathetic (no sympathetic innervation)
M3 receptors - constriction
No sympathetic but B2 receptors can be activated by circulating epinephrine, causing dilation

37

What is the predominant tone of arterioles?

Sympathetic
Alpha receptors - constriction

38

What is the predominant tone of veins?

Sympathetic
Alpha receptors - constriction

39

What is the predominant tone of the iris?

Parasympathetic
M2 receptors - constriction

40

What are the two negative feedback loops involved in regulation of MAP?

Hormonal loops (renin/angiotensin)
ANS loop (Baroreceptor reflex)

41

What are the 4 variables that the sympathetic system directly influences that controls blood pressure?

Increased TPR
Heart rate
Contractile force
Increased venous tone

42

What variable does the parasympathetic system influence that controls blood pressure?

Decreased heart rate

43

Describe the autonomic functions in the eye

Sympathetic - Alpha1 receptor, mydriasis (dilation)
Parasympathetic - M3 receptor, miosis (constriction)

44

What are the symptoms of Horner's syndrome?

Anhydrosis
Miosis (constriction)
Ptosis

45

Describe test for Horner's syndrome and the rationale of each step

Cocaine - inhibits NE reuptake, should cause mydriasis (dilation)
- If no dilation, indicates a problem at either pre or postganglionic neuron

Hydroxyamphetamine - causes release of NE from presynaptic vesicles, should cause mydriasis (dilation) and requires intact postganglionic nerve with some NE in vesicles.
- If no dilation, indicates a problem with the postganglionic neuron

46

What drug inhibits uptake of choline by Na+-coupled cotransporter?

Hemicholinium
Reduced uptake of choline = neuromuscular dysfunction

47

What drug activates alpha 2 receptors, thereby inhibiting NE release?

Clonidine