Intro to PNS

Question 1

Describe pathway of somatic nerves

Answer 1

Single neuron efferent pathway

Directly innervates skeletal muscle

Question 2

Describe pathway of sympathetic nerves

Answer 2

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

Question 3

Describe pathway of parasympathetic nerves

Answer 3

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

Question 4

Where does the sympathetic division originate?

Answer 4

T1-L2 (thoraco-lumbar division)

Question 5

Where does the parasympathetic division originate?

Answer 5

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

Question 6

What is the neurotransmitter of somatic nervous system?

Answer 6

ACh

Question 7

What is the preganglionic neurotransmitter of parasympathetic nervous system?

Answer 7

ACh

Question 8

What is the postganglionic neurotransmitter of parasympathetic nervous system?

Answer 8

ACh

Question 9

What is the preganglionic neurotransmitter of sympathetic nervous system?

Answer 9

ACh

Question 10

What is the postganglionic neurotransmitter of sympathetic nervous system?

Answer 10

NE

Question 11

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

Answer 11

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

Question 12

Describe synthesis and packaging of ACh

Answer 12

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

Question 13

Describe termination of ACh action

Answer 13

ACh rapidly degraded into choline and acetate by AChE

Choline is taken back up and recycled by Na-coupled choline cotransporter

Question 14

Describe synthesis and packaging of NE

Answer 14

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

Question 15

Describe termination of NE action

Answer 15

NE reuptake into nerve terminal by NET

NE diffuses from the site of action

Question 16

How is epinephrine formed?

Answer 16

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

Question 17

What are metabolic products of catecholamines?

Answer 17

Normetanephrine and metanephrine
MHPG (MOPEG)
VMA

Question 18

What are the general categories of cholinergic receptors?

Answer 18

Nicotinic

Muscarinic

Question 19

What are the general categories of adrenergic receptors?

Answer 19

Alpha

Beta

Question 20

What type of receptor are nicotinic receptors?

Answer 20

Ionotropic

Question 21

What type of receptor are muscarinic receptors?

Answer 21

G protein coupled receptors

Question 22

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

Answer 22

Nm (neuromuscular junction)

Nn (autonomic ganglia, adrenal medulla)

Question 23

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

Answer 23

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

Question 24

What is the response of M1 activation?

Answer 24

Late EPSP in ganglia

Question 25

What is the response of M2 activation?

Answer 25

Decreased heart rate and contractility, slows spontaneous depolarization

Question 26

What is the response of M3 activation?

Answer 26

Contraction of smooth muscle | Secretion

Question 27

What type of receptor are adrenergic receptors?

Answer 27

G protein coupled receptors

Question 28

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

Answer 28

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

Question 29

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

Answer 29

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

Question 30

What is the response of Alpha1 activation?

Answer 30

Vasoconstriction GU relaxation Glycogenolysis and gluconeogenesis

Question 31

What is the response of Alpha2 activation?

Answer 31

Decreased transmitter release, causes contraction

Question 32

What is the response of Beta1 activation?

Answer 32

Increased heart rate, force of contraction, and renin release

Question 33

What is the response of Beta2 activation?

Answer 33

Relax smooth muscle | Increase glycogenolysis and K uptake

Question 34

What is the response of Beta3 activation?

Answer 34

Increased lipolysis

Question 35

What is the response of dopaminergic receptor activation by NE?

Answer 35

Relaxation of renal vascular smooth muscle

Question 36

What is the predominant tone of bronchiole smooth muscle?

Answer 36

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

Question 37

What is the predominant tone of arterioles?

Answer 37

Sympathetic | Alpha receptors - constriction

Question 38

What is the predominant tone of veins?

Answer 38

Sympathetic | Alpha receptors - constriction

Question 39

What is the predominant tone of the iris?

Answer 39

Parasympathetic | M2 receptors - constriction

Question 40

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

Answer 40

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

Question 41

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

Answer 41

Increased TPR Heart rate Contractile force Increased venous tone

Question 42

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

Answer 42

Decreased heart rate

Question 43

Describe the autonomic functions in the eye

Answer 43

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

Question 44

What are the symptoms of Horner's syndrome?

Answer 44

Anhydrosis Miosis (constriction) Ptosis

Question 45

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

Answer 45

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

Question 46

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

Answer 46

Hemicholinium | Reduced uptake of choline = neuromuscular dysfunction

Question 47

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

Answer 47

Clonidine