B.1- cholinergic transmission

Question 1

agents causing presynaptic inhibitory effect

Answer 1

𝝰₂
M₂
Hemicholinium 
Vesamicol 
Botulinum toxin

Question 2

agents causing presynaptic stimulatory effect

Answer 2

M₁
B₂
AT₁
4-Aminopyridine 
Latrotoxin (spider venom)

Question 3

what are the function of Acetylcholine (Ach) in the synaptic cleft?

Answer 3

1. activation of postsynaptic receptors (physiological effect)
2. activation of presynaptic autoreceptors
3. rapid degradation by acetylcholinesterase

Question 4

what does Hemicholinium do?

Answer 4

inhibits transport of choline into the nerve terminal`

Question 5

what does Vesamicol do?

Answer 5

inhibits transport of Ach into storage vesicles

Question 6

what does Botulinum toxin do?

Answer 6

inhibits the release of Ach- loaded vesicles (interfere with SNARE proteins)

Question 7

indications for Botulinum toxin

Answer 7

Blepharospasm (abnormal blinking)
Hyper- hydrosis (↑ sweating)
dystonia (twisting movement)
cosmetics

Question 8

where can we find Latrotoxin?

Answer 8

in spider venom

Question 9

function of 4-aminopyridine

Answer 9

inhibits K channels–> depolarization–> excitatory signal–> neurotransmitter release

Question 10

function of Latrotoxin

Answer 10

creates pores along the membrane–> Ca² influx–> excitatory signal–< neurotransmitter release

Question 11

name the cholinergic receptors and their mechanism of action

Answer 11

muscarinic receptors: "qiq"
M1- Gq coupled
M2-Gi coupled
M3- Gq coupled 
nicotinic (Na-K ion channels): 
Neural (Nn) 
Muscular (Nm)

Question 12

where is M1 found and what is the effect

Answer 12

nerve endings

↑ gastric acid secretion

Question 13

where is M2 found and what is the effect

Answer 13

heart

inhibits cardiac activity

Question 14

where is M3 found and what is the effect

Answer 14

smooth muscle, endothelial cells, glands

bronchoconstriction, GI secretions and motility associated with digestion

Question 15

where is Nn found and what is the effect

Answer 15

ANS ganglia, adrenal medulla

activation of sympathetic and parasympathetic nerves

Question 16

where is Nm found and what is the effect

Answer 16

Neuromuscular end plates

causes excitatory post-synaptic potential (EPSP)

Question 17

synthesis of Ach

Answer 17

ChAT - Choline Acetyltransferase converts Acetyl-coA + Choline into Ach in the nerve terminal

Question 18

storage of Ach

Answer 18

Ach is transported into the vesicle via VAT- vesicle-associated transporter
*inhibited by vesmicol

Question 19

Release of Ach

Answer 19

Ca² influx induces action potential–>Ach is released into the synaptic cleft
*inhibited by botulinum toxin

Question 20

Reception and Recognition of Ach

Answer 20

Ach acts on muscarinic and nicotinic receptors on the postsynaptic cell, and some presynaptic receptors on neurons

Question 21

Termination of Ach

Answer 21

Acetylcholinesterases or pseudocholinesterase hydrolyze Ach into choline and acetate

Question 22

Ach recycling

Answer 22

Ach is taken back up into the neuron through presynaptic receptors
*rate-limiting step

Question 23

cholinergic effects on the eye

Answer 23

miosis ↑M3
mydriasis ↓M3
accommodation ( ↑M3--> contracted ciliary muscle)
↓ of intraocular pressure
↑ lacrimation

Question 24

cholinergic effects on the blood vessels

Answer 24

constriction of coronary a.