Lecture 6 - Neuromuscular Junction

Question 1

Synaptic vesicles release?

Answer 1

Acetylcholine

Question 2

What are dense bars?

Answer 2

Anchored to the presynaptic membrane

Tethered to synaptic vesicles by short filaments

Question 3

What is the synaptic gutter?

Answer 3

Trough in the surface of a sarcolemma where the axon terminal makes contact
Comprised of subneural clefts

Question 4

What is the synaptic cleft?

Answer 4

very narrow gap (20-30nm) between the axolemma and the sarcolemma in the synaptic gutter

Question 5

When does the tubular channel of the sarcolemma open?

Answer 5

When two ACH molecules attach to its alpha subunits

Question 6

Where are vesicles formed in the neuron?

Answer 6

Golgi apparatus

Question 7

How are vesicles transported to the axon terminus?

Answer 7

Axonal transport

Question 8

Where is ACH synthesized?

Answer 8

in the cytosol of the axon terminal

Question 9

What happens when an action potential arrives at the axon terminal?

Answer 9

Voltage gated Ca2+ channels open and Ca2+ ions enter the terminus

Question 10

What is the extracellular concentration of Ca2+? Higher or lower than intracellular?

Answer 10

1-2 mM

higher than intracellular

Question 11

What is the intracellular concentration of Ca2+? Higher or lower than extracellular?

Answer 11

<10^-6 M

Question 12

What initiates the action potential on the sarcolemma?

Answer 12

The end plate potential

Question 13

what is the magnitude of the end plate potential?

Answer 13

50-70 mV

Question 14

What is the end plate potential caused by?

Answer 14

Large influx of sodium ions into the sarcolemma