changing membrane potentials

Question 1

changes in membrane potential under lie main forms of signalling such as

Answer 1

1. action potential in nerve and muscle cells
2. triggering and control of muscle and contraction
3. control of secretion of hormones and neurotransmitters
4. transduction of sensory information into electrical activity by receptors
5. postsynaptic actions of fast synaptic transmitters

Question 2

depolarization

Answer 2

a decreased in the size of the membrane potential from its normal value
cell interia becomes less negative

Question 3

hyperpolarization

Answer 3

an increase in the size of the membrane potential from its normal vaule
cell interior becomes more negative

Question 4

membrane portianl arise as a result of

Answer 4

selective ionic permeability

Question 5

increasing membrane permeability to a particular ion moves the membrane potential towards

Answer 5

the equilibrium potential

Question 6

K+ equillibium potential

Answer 6

-95mV

Question 7

Na+ equilibrium portential

Answer 7

+70mV

Question 8

K+ channels opening will cause

Answer 8

hyperpolarization

Question 9

Na+ channels opening will cause

Answer 9

depolarization

Question 10

as membrane are never selective for one ion what equarion can we use to calculate the resting equilibrium potential

Answer 10

goldman-hodgkin-katz equation

Question 11

control channel activity

Answer 11

1. ligand gating
2. voltage gating
3. mechanical gating

Question 12

how can we distinguish between fast and slow synaptic transmission

Answer 12

fast- the receptor protein is also an ion channel

slow-the receptor and channel are separate proteins

Question 13

excitatory synapses

Answer 13

excitary transmission open ligand gated chanels that cause membrane depolarisation
loger than action potential
graded with amount of transmitter
depolarisation

Question 14

inhibitory synapses

Answer 14

inhibitory trnsmitters open ligand-gated channels that cause depolarisation
hyperpolarsation

Question 15

other factors that can influence membrane potential

Answer 15

changes in ion concentration

electrogenic pumps e.g Na+/K+ATPase

Question 16

Absolute refractory period

Answer 16

Na+ channels in incative state

Question 17

relative refractory period

Answer 17

Na+ channels are recovering in inactivated form

Question 18

step 1 of action potential

Answer 18

depolarization to threshols triggers the opening of many voltgage gated Na channels

Question 19

action potential step 2

Answer 19

influx of Na+ produced the rapid upstroke of the action potential (membrane potential moves towatds Ena)

Question 20

action potential step 3

Answer 20

this depolarization causes inactivation of Na+ channel and opening of voltage gated K+ channels

Question 21

action potential step 4

Answer 21

Na+ influx stops and the increased K+ effluc leads to repolarisation moves towards Ek