lecture 8 - synaptic transmission

Question 1

How are Action Potentials regenerative in their propogation?

Answer 1

the AP travels along the axon by each section being triggered by the adjacent membrane by the spread of depolarisation

Question 2

Why can action potentials only propagate in one direction?

Answer 2

Because the area behind the action potential is in its absolute refractory period so the depolarisation can only spread forwards

Question 3

Why does increasing axon diameter increase the speed of AP conduction?

Answer 3

Reduces the resistance to flow along the axon

Question 4

How does myelin increase AP velocity?

Answer 4

Increases membrane resistance to reduce current leak and reduce capacitance. Ions spread further before AP needs to regenerate increasing the speed

Question 5

Are unmyelinated or myelinated axon more energy intensive, and why?

Answer 5

Unmyelinated - more ions must be used meaning greater ion pump action

Question 6

What are the gaps between myelin in an axon?

Answer 6

Nodes of ranvier

Question 7

Why are the nodes of Ranvier required for AP propagation?

Answer 7

Space for voltage gated Na+ ion channels to allow AP to spread

Question 8

What 2 factors have a minor effect on AP velocity?

Answer 8

Temperature, metabolic factors

Question 9

At a synapse, what ion channels are opened to trigger the release of neurotransmitter via vesicles?

Answer 9

Voltage gated Ca2+ channels

Question 10

What is the name of the gap between a pre- and post - synaptic cells?

Answer 10

Synaptic cleft

Question 11

What type of receptor is used to bind neurotransmitter in a post-synaptic cell?

Answer 11

Ionotropic receptor