hms 7

Question 1

how does action potential occur

Answer 1

1. stimulus-gated sodium channels open- depolarisation
2. threshold is reached, voltage gated channels open
3. voltage gated channels open, depolarizes further
4. magnitude of action potential peaks at +30mV voltage gated Na+ channels close
5. repolarisation- voltage gated K+ channels open
6. brief hyperpolarisation, RMP restored by NaK pump, return ion channels to resting state below threshold

Question 2

4 types of potentials

Answer 2

resting -70mV
local- varies
threshold- -59mV
action- +30mV

Question 3

conduction of action potentials

Answer 3

relies on spread of depolarising electrical signal

along axon to activate next set of voltage gated Na+ channels

Question 4

2 types of refractory period

Answer 4

absolute: no depolarization and response possible
relative: requires large stimulus for repolarization

Question 5

function of refractory period

Answer 5

to ensure actin potential only travels one way down axon

Question 6

how to improve conduction speed

Answer 6

myelination insulation increases conduction speed

Question 7

schwann cells

Answer 7

type of oligodendrocyte insulating myelin sheath
regeneration of action potential in nodes of ranvier
saltatory conduction