ANS1

Question 1

ANS

Answer 1

• 2 divisions- SNS and PNS
• SNS is thoracolumbar
• PNS is craniosacral
• enteric is sometimes in
• SNS and PNS innervate smooth and cardiac muscle, secretory epithelia, glands
• arterial pressure, GI motility and secretions, bladder, sweating, temp
• SNS is fight or flight, PNS is rest and digest
• survival possible but function compromised without

Question 2

SNS activation

Answer 2

1. stimulation of heart rate at SA node- pos chronotropic effect
2. stimulation of AV nodal conduction- pos dromotropic effect
3. stimulation of myocardial contractility- pos inotropic effect

Question 3

PNS activation

Answer 3

1. inhibition of HR at SA node- neg chronotropic
2. inhibition of AV nodal conduction- neg dromotropic
3. inhibition of atrial contractility- mild, neg inotropic effect
   - both systems always on, one just wins out

Question 4

2 synapse pathway

Answer 4

• preganglionic neuron in CNS and postganglionic neuron either in paravertebral or near organ and then target cell
• pre is short in SNS, long in PNS
• post is long in SNS, short in PNS
• pre are small slow myelineated type B
• post are small slow unmyelinated type C

Question 5

divergence

Answer 5

-SNS pre neurons make multiple contacts to post- about 100

PNS only 10-15

Question 6

en passant synapses

Answer 6

-single axon has broad actions in target tissues

Question 7

somatic neurons

Answer 7

• pathway is monosynaptic

- Ach binds to N1 nicotinic cholinergic receptors on post synaptic membrane of skeletal muscle

Question 8

N1 receptor antagonist

Answer 8

-d-tubocurarine

Question 9

Nicotinic agonist

Answer 9

nicotine

Question 10

SNS and PNS pre ganglionic neuron

Answer 10

• releases Ach

- binds to N2 nicotinic cholinergic receptors on postsynaptic membrane of the postganglionic neuron

Question 11

N2 receptor antagonist

Answer 11

-hexamethonium

Question 12

post ganglionic PNS

Answer 12

• Ach

- receptor is muscarinic cholinergic (type 1-5)

Question 13

post ganglionic SNS

Answer 13

• norepi
• receptor is adrenergic receptor a or B
• some can also still release Ach and go to muscarinic receptors

Question 14

SNS and adrenal

Answer 14

• directly innervates chromaffin cells of adrenal medulla
• releases epi and some norepi
• hormones in blood now, affect multiple tissues
• 5-10 times longer, and reach tissues without their own sympathetic innervation
• secretes enough epir and norepi to maintain near normal BP if sympathetic innervation to heart is disrupted

Question 15

SNS target tissues

Answer 15

• express distinct andrenergic receptor subtypes with different affinities for epi and norepi
• sometimes use muscarinic cholinergic receptors-eccrine sweat glands
• are broadly activated by epi/norepi from medulla

Question 16

PNS target tissues

Answer 16

-express various combinations of 5 muscarinic cholinergic receptors

Question 17

alpha 1

Answer 17

BV

• norepi binds, activates G protein
• alpha/GTP subunit activates phospholipase C
• cleaves PIP2 to DAG and IP3 (releases Ca from ER/SR)
• Ca and DAG activate protein kinase C

Question 18

beta1

Answer 18

heart

Question 19

beta2

Answer 19

bronchi

Question 20

mechanism of B receptors

Answer 20

• norepi binds, activates G protein
• alpha/ATP subunit activates adenylyl cyclase
• cAMP activates physiologic actions

Question 21

mechanism of nicotinic cholinergic receptors

Answer 21

• somatic muscle cells and post synaptic receptors for 1 synapse for SNS and PNS (somatic N1, ANS N2)
• Ach binds
• conformational change
• depolarization and Na in makes EPSP

Question 22

muscarinic cholinergic receptors

Answer 22

• exert action through G proteins linked to:
  1. PLC leading to generation of IP3 and DAG (M1,3,5)- like a1
  2. inhibition of andenylate cyclase leading to decreased cAMP (m2,4)

Question 23

d-tubocurarine

Answer 23

N1 nicotinic Ach receptor antagonist

Question 24

hexamethonium

Answer 24

N2 nicotinic Acg receptor antagonist

Question 25

atropine

Answer 25

M1,3,5 muscarinic Ach receptor antagonist

Question 26

propanolol

Answer 26

-B1 andrenergic (which is more sensitive to epi than norepi) receptor antagonist

Question 27

beta vs alpha

Answer 27

• alpha more sensitive to norepi
• beta to epi
• reflected by adrenal medullary contribution
• epi affects heart, lungs, liver
• norepi affects vasculature

Question 28

Massive SNS discharge results in

Answer 28

• mydriasis and eyelid retraction (a1)
• increased HR and force of contraction (b1)
• bronchial dilation (B2)
• vasoconstriction (a1)*
• sweating- muscarinic
• increased cellular met, epi from adrenal medulla (a and B)
• decreased GI motility, smooth muscle walls (a and B) and increased contraction of sphincters (a1)

*there is increased blood flow to active muscles (vasodilation via B-andrenergic receptors of skeletal and coronary muscle) but adenosine causes most of the vasodilation

Question 29

pheochromocytoma

Answer 29

• neoplasm of the adrenal medulla (sometimes extra medullary
• secrete excessive amounts of norepi, epi, or both resulting in sustained hypertension, cold hands and feet, sweating, feeling hot
• increased dopamine secretion rare
• occur in less than 0.1% of hypertensive patients
• observed at all ages males and females but esp during 4th-5th decade
• tumors are well circumscribed with weights ranging from 1g to several kg
• treatment is excise the tumor
• can treat a1 abd b1 antagonists can be used

Question 30

horners syndrome

Answer 30

• anhidrosis, ptosis, miosis

- injuries to SNS produce deficits ipsilateral to the lesions