Lecture 5: Nervous System 4 Continued

Question 1

5 steps of a chemical synapse

Answer 1

1. Action potential propagation in a presynaptic neuron
2. Calcium entry
3. Release of neurotransmitter by exocytosis
4. Binding of neurotransmitter to receptor
5. Opening of specific ion channel

Question 2

After it has produced the appropriate response in the post synaptic cell, the neurotransmitter must be

Answer 2

inactivated or removed

Question 3

Three ways to inactivate/remove a neurotransmitter

Answer 3

1. Diffuse away from the synaptic cleft
2. Inactivated by specific enzymes within the postsynaptic membrane
3. Be actively taken up into the axon terminal by transport mechanism in the presynaptic membrane

Question 4

Norepinephrine removal (3)

Answer 4

• May diffuse out of the synaptic space and enter general circulation
• May be recaptured by an uptake system that pulls it back into the neuron using an ATP-dependent pump
• Can be degraded by MAO, COMP, or both

Question 5

MAO

Answer 5

Monoamine oxidase

Present in the nerve terminal that released it

Question 6

COMP

Answer 6

Catechol-O-methyltransferase

Example: in liver and kidney

Question 7

What accounts for very fast conduction of action potentials?

Answer 7

Electrical synapse

Question 8

Two places electrical synapse occurs

Answer 8

Cardiac muscle

Some types of smooth muscle

Question 9

Example of electrical synapse

Answer 9

Rapid cell-cell communication in cardiac myocytes