Nervous System - Action Potentials & Synaptic Transmission

Question 1

voltage gated na+ channels

Answer 1

open quick when membrane depolarises
na+ influx = rapid depolarisation

Question 2

voltage gated k+ channels

Answer 2

open slowly & membrane repolarises
k+ exits = repolarisation

Question 3

resting membrane potential

Answer 3

-70mv where inside neuron is more negative than outside

Question 4

rest stage

Answer 4

channels are closed, at RMP

Question 5

depolarisation

Answer 5

stimulus caused MP to reach threshold (-55mV). voltage gated na+ channels open

Question 6

repolarisation

Answer 6

na+ channels close and k+ channels open

Question 7

hyperpolarisation

Answer 7

k+ channels stay open a little longer causing RMP to go below -70mV

Question 8

return to rest stage

Answer 8

na+/k+ atpase restore RMP

Question 9

absolute refractory period

Answer 9

no new AP can start. na+ channels inactivated

Question 10

relative refractory period

Answer 10

stronger stimulus is needed. na+ channels resetting

Question 11

synaptic transmission process

Answer 11

AP arrives at terminal - voltage gated ca2+ channels open - ca2+ influx triggers vesicles to release neurotransmitter into synaptic cleft
neurotransmitter binds receptors on postsynaptic neuron - ion channels open - postsynaptic potential

Question 12

ap speed determinants

Answer 12

myelination (speeds conduction via saltatory conduction)
axon diameter (larger = less resistance = faster conduction)

Question 13

temporal summation

Answer 13

multiple signals from one neuron in rapid succession

Question 14

spatial summation

Answer 14

signals from multiple neurons combine

Question 15

local potentials

Answer 15

excitatory - depolarising, na+ channels opening
inhibitory - hyperpolarising, k+ channels opening