Synapse & Neuromuscular Junction

Question 1

How do cells communicate electrically?

Answer 1

Gap junctions allow movement of ions

Question 2

How do cells communicate chemically?

Answer 2

Synapses, hormones, cytokines, etc

Question 3

How many synapses can there be on a single neuron?

Answer 3

~10,000

Question 4

What is an axo-dendritic synapse?

Answer 4

Axon of a neuron connects with the dendrite of another

Question 5

What is an axo-somatic synapse?

Answer 5

Axon of a neuron connects with a cell body

Question 6

What is an axo-axonic synapse?

Answer 6

Axon of one neuron connects with the axon of another

Question 7

Why are action potentials in muscle cells broader?

Answer 7

Ca2+ entering for contraction as well as depolarisation (excitation-contraction coupling)

Question 8

What is the range of current measured during sub-threshold muscle stimulation?

Answer 8

10nA

Question 9

What is the range of voltage measured during sub-threshold muscle stimulation?

Answer 9

10mV

Question 10

How long does a single muscle depolarisation (sub-threshold) last for?

Answer 10

2ms

Question 11

What can inhibit the reuptake of serotonin?

Answer 11

Selective Serotonin Reuptake Inhibitors/SSRI

Question 12

How long does a muscle action potential last?

Answer 12

10ms

Question 13

What enzyme degrades ACh?

Answer 13

Acetylcholine-esterase

Question 14

What does the term “high safety factor” mean?

Answer 14

More neurotransmitter released than required to reach threshold to ensure an action potential is triggered

Question 15

What are miniature end plate potentials?

Answer 15

Depolarisations smaller than end plate potentials that occur due to the release of a single presynaptic vesicle

(Random sub-threshold events)

Question 16

What is an end plate potential?

Answer 16

Depolarisation of muscle fibre

Can be sub or supra-threshold

Question 17

What ion coordinates miniature end plate potentials?

Answer 17

Ca2+

Results in excitatory post-synaptic potentials

Question 18

What do IPSPs do?

Answer 18

Inhibitory post-synaptic potentials inhibit some action potentials

Question 19

If the membrane becomes permeable to an ion what will happen?

Answer 19

Ion will move down its electrochemical gradient

Driving the Vm towards its own equilibrium potential

Question 20

How should you alter the charge of the cell to stop Na+ entering?

Answer 20

Make it more positive (repulsion)

Question 21

How should you alter the charge of the cell to stop K+ leaving?

Answer 21

Make it more negative (attract K+ back)

Question 22

What gives rise to the membrane potential?

Answer 22

Separation of ions