L12 ANS Continued

Question 1

the physiological event elicited by a NT depends on the ____, not the _____

Answer 1

receptor

transmitter

Question 2

what receptor is in somatic nervous system for skeletal muscle motor neurons?

Answer 2

nicotinic receptor (N1 or Nm)

Question 3

what receptor is in Autonomic NS connecting pre gang to post gang?

Answer 3

nicotinic receptor (N2 or Nn)

Question 4

what are cholinergic receptors divided into?

Answer 4

nicotinic

muscarinic

Question 5

what type of channel are ALL nicotinic receptors?

Answer 5

ligand-gated cation selective channels (ionotropic receptors)

Question 6

what type of receptors are muscarinic receptors?

Answer 6

G protein linked (GTP-binding proteins) transmembrane receptors (metabotropic receptors)

Question 7

activation of muscarinic receptors can effect changes in what?

Answer 7

intracellular 2.d messengers - Ca2+ and cAMP

Question 8

nicotinic and muscarinic receptors both bind what?

Answer 8

ACh - named after nicotine and muscarine that bind to them and mimic ACh effects!

Question 9

what is the effect of ACh on nicotinic receptors?

Answer 9

Stimulatory

Question 10

where are nicotinic receptors found?

Answer 10

• motor end plates of skeletal muscles
• all postgang neurons of SNS and PNS
• chromaffin cells of adrenal medulla

Question 11

What is the effect of ACh on muscarinic receptors?

Answer 11

either inhibitory or excitatory

Question 12

where are muscarinic receptors found?

Answer 12

• ALL effector organs of PNS ( heart, GI tract, bronchioles, bladder, male genitalia)
• certain effector organs of SNS (sweat glands, vascular smooth muscle of skeletal muscle)

Question 13

where are nicotinic receptors located?

Answer 13

CNS autonomic ganglia (N1/Nm) and NMJ (N2/Nn)

Question 14

of the 5 subunits that make up the nicotinic receptor, what is required for the channel to open?

Answer 14

requires 2 ACh molecules binding to 2 alpha subunits

Question 15

what happens with high levels and prolonged activation of ACh binding site?

Answer 15

shows densensitization

Question 16

what prevents the long duration of ACh in synaptic cleft so that nicotinic receptors do not desensitize?

Answer 16

acetylcholinesterases

Question 17

what is the nicotinic receptor ion channel selective for?

Answer 17

Na and K
more Na comes into the cell than K leaving the cell
= depolarization

Question 18

what are autonomic receptors coupled to?

Answer 18

heterotrimeric GTP binding proteins (G proteins)

Question 19

what are the characteristics of the G protein?

Answer 19

snake like transmembrane protein
3 subunits - alpha, beta, gamma
stimulatory or inhibitory

Question 20

what does the alpha subunit bind to?

Answer 20

either GDP = inactive / GTP = active == stimulatory/inhibitory activity in alpha subunit

Question 21

where are adrenergic receptors found?

Answer 21

target tissues of SNS

Question 22

what activates adrenergic receptors?

Answer 22

catecholamines NE (from post gang neurons) and E (from adrenal medulla)

Question 23

adrenergic receptors are divided into?

Answer 23

alpha and beta

then subdivided into alpha 1, alpha 2, beta 1, beta 2

Question 24

each adrenergic receptors has a different mechanisms of action which leads to?

Answer 24

different physiological effects

Question 25

NE is a better ____ receptor agonist

Answer 25

alpha

Question 26

E is a better ____ receptor agonist

Answer 26

beta - ESPECIALLY BETA 2

Question 27

How are catecholamine responses terminated?

Answer 27

1. reuptake into presyn terminal
2. metabolism to inactive metabolite
3. diffusion away from synaptic cleft