Neuromuscular Transmission

Question 1

One for One Transmission

Answer 1

AP in presyn usually leads to AP in muscle membrane

Question 2

Mu Conotoxin

Answer 2

Poison from snails that blocks Vg Na channels in muscle fibers (so diff properties from nerve ones) so you can see the EPP from ACh w/out AP

Question 3

6 Differences b/w NM Transmission and CNS Synaptic Transmission

Answer 3

1) NT at NM synapse always ACh
2) Less NT released at CNS
3) Rs are different
4) Different/more varied ways to clear out synapse in CNS
5) Can hyper or depolarize in CNS, NM only depols
6) In NM, almost always depol’d to threshold. CNS usually isn’t

Question 4

Miniature End Plate Potentials (m.e.p.p.s)

Answer 4

Spontaneous releases of exactly 1 synaptic vesicle, so they’re the size of average quanta

Question 5

Black Widow Alpha Latrotoxin

Answer 5

Increases freq of m.e.p.p.s for 20-40 minutes, depleting synaptic vesicles

Question 6

Eq for EPP Amplitude

Answer 6

k[ACh]^2[R]

Question 7

Desensitization

Answer 7

Prolonged exposure to high ACh leaves too many Rs in inactive state and decreases response to ACh

Question 8

D-tubocurare

Answer 8

Binds reversibly w/ AChR

Question 9

Alpha-bungarotoxin (2)

Answer 9

From snake bungarus and binds to AChR irreversibly. Can be used to isolate R bc toxin can be labeled radioactively

Question 10

Neostigmine

Answer 10

Anticholinesterase. Have to be careful bc can lead to desensitization

Question 11

Botulism Toxin

Answer 11

From bacteria, one of the most poisonous toxins bc proteases that degrade proteins necessary for NT release so one molecule can do extensive damage

Question 12

Tetanus Toxin

Answer 12

Degrades release prot synaptobrevin in inhibitory nerve endings so no more GABA/gly release and get overexcitation and generalized contractions of opposite muscles

Question 13

2 Effects of Decreasing Ca in Bathing Solution

Answer 13

1) Muscle membrane threshold decreased

2) Amount of NT released decreased so size of EPP smaller

Question 14

Short-Term Synaptic Plasticity (STP)

Answer 14

Change in amount of transmitter released by each nerve impulse during repetitive stimulation

Question 15

Post-Tetanic Potentiation

Answer 15

Huge spike in EPP amplitude when stimulated after a break following repetitive stimulation

Question 16

Lambert-Eaton Myasthenic Syndrome (LEMS)

Answer 16

Autoimmune disease that reduces #s of Ca channels in presyn nerve terminals, so muscle strength has to build up

Question 17

3,4 Diaminopyridine

Answer 17

Treatment for LEMS that blocks some of Vg delayed rectifier K+ channels slowing the return of AP and increasing Ca entry