Action Potentials

Question 1

Dendrites and cell body ion channels

Answer 1

Chem-gated Na + and cl - (and others - mechanically gated for certain neurons)

Question 2

Axon hillock ion channels

Answer 2

Voltage gated Na + and K + channels

Question 3

Axon ion channels

Answer 3

Voltage gated Na + and K + channels

Question 4

Axon terminals ion channels

Answer 4

Voltage gated Ca 2 + channels

Question 5

Local potentials

Answer 5

Change in voltage in a small location on the dendrites or cell body membrane of a post synaptic cell

Question 6

EPSP

Answer 6

Excitatory neurotransmitter opens Na + channels, causing depolarization

Question 7

IPSP

Answer 7

Releases inhibitory neurotransmitter that opens K + or cL _ channels to cause hyperpolarisation

Question 8

Spatial summation

Answer 8

Multiple neurons input

Question 9

Temporal summation

Answer 9

Input from repeated firing of one neuron

Question 10

Threshold potential

Answer 10

–60mv

Question 11

Action potential steps

Answer 11

1 VG Na + channels open,2 massive influx causes rapid depolarization 3 at ~30mv, vg Na + inactivates, vg k+ opens and cell repolarizes ,4 VG k+ close slowly causing hyperpolarisation, 5 all VG k+ channels close and membrane goes to -70mv

Question 12

Absolute refractory period

Answer 12

2nd ap cannot be generated because VG Na + channels are open or inactive

Question 13

Relative refractory period

Answer 13

2nd AP can only be generated if stimulus is larger than normal because some VG Na + channels are shifting from inactive to closed