10/13 Anatomy & Physiology of Neuromuscular Junction - Roger & Izard 2017 (Completed)

Question 1

What is the muscle to neuron relationship? 2

Answer 1

muscles fibers are innervated by a single motor neuron (motor unit)

Question 2

What occurs during the junctional transmission step of neurotransmission? 3

Answer 2

Synthese of Ach

Storage of Ach

release of Ach

destruction of Ach

Question 3

How is Acetylcholine (ACh) synthesized in the neuron? 5

Answer 3

choline transported into cell via CHT receptor

Acetyl-CoA from mitochondria combines w/ choline via Choline Acetyltransferase (ChAT)

Question 4

How is Acetylcholine (ACh) loaded into vesicles? 6

Answer 4

via the transporter protein ACh vesicular transporter (VAT)

utilizes ATP

Question 5

what magnitude of ACh vesicles are present at the pre-synaptic cleft? 7

Answer 5

100,000s

Question 6

How is ACh released from their vesicles into the synaptic cleft? 7

Answer 6

depolarization of the neuron causes voltage-gated Ca2+ channels to open (VGCC)

Ca2+ induces vesicles to release contents into synaptic cleft

Question 7

What are the docking and fusion of vesicle to PM proteins? 8

Answer 7

VAMP

SNAPs (SNAP 25)

Question 8

What is vesicle release dependent on? 8

Answer 8

Signal strength

Cell type

Question 9

What breaks down acetylcholine after transmission? What is ACh broken down into? 10

Answer 9

Acetylcholinesterase (AChE)

Broken down into:
Choline
acetate

Question 10

What utilizes Nicotinic (inotropic) receptors? 12

Answer 10

Skeletal muscle

Question 11

What utilizes Muscarinic (metabotropic) receptors? 12

Answer 11

Smooth muscle

Cardiac muscle:
decrease HR
decreased conduction velocity

Question 12

What are the five subtypes of Muscarinic ACh receptors in mammals? 13

Answer 12

M1, M4, M5 –> CNS

M2 –> Heart

M3 –> Smooth muscle

Question 13

how many subunits are there in a Nicotinic ACh receptor? 14

Answer 13

4 subunits

Receptor requires 2 ACh for activation

Question 14

What amino acids line a nicotinic ACh receptor? 15

Answer 14

Negatively charged aa’s

Aspartic acid
glutamic acid

Question 15

What is a Nicotinic ACh receptor selective to? 15

Answer 15

Na+
Ca2+
K+

Question 16

What are the subtypes of Nicotinic ACh Receptors? 17

Answer 16

Nm –> α, β, γ, δ, ε

Nn –> α, β or α only

Question 17

What is the role of laminin-β2?

Answer 17

Tethers the vesicle to the nerve cell

Question 18

What is Tetrodotoxin? 11 Izard

Answer 18

Drug contained within flesh of puffer fish

Blocks CNS/PNS

Question 19

What is the mechanism of action of Tetrodotoxin? 11 Izard

Answer 19

Blocks diffusion of Na+ through Na+ channel

Prevents depolarization = no action potential

Question 20

What drugs does Bupivacaine interact with? 14 Izard

Answer 20

Prolongs hypertension in pts with MAOIs and TCAs

Question 21

What is the action of Botulinum toxin? 15 Izard

Answer 21

Prevents release of ACh from axon endings @ NMJ

Causes paralysis

Question 22

What is the action of Tetanus Toxin? 18 Izard

Answer 22

Causes extreme lockjaw

Travels to spinal cord and causes muscle cramps