Neurophysiology

Question 1

membrane potential is what

Answer 1

voltage that exists across the plasma membrane of a cell. difference between charged molecules within cell compared to outside of cell

Question 2

what 2 major molecules are responsible for potential

Answer 2

sodium and potassium

Question 3

what is resting membrane potential

Answer 3

70

Question 4

is the outside of the cell more positive or negative

Answer 4

positive

Question 5

within the cell is there a higher or lower conc of K+ than Na+

Answer 5

higher

Question 6

is the plasma membrane more permeable to k+ or na+

Answer 6

k+

Question 7

signal transmission involves 2 diff membrane potentials

Answer 7

local (receptor synaptic) and action

Question 8

potential involve what?

Answer 8

depolarisation and repolarisation

Question 9

depolarisation is what

Answer 9

decrease in potential, potential becomes less negative

Question 10

repolarisation is what

Answer 10

return of cell potential

Question 11

membrane potential is case the what of ion channels

Answer 11

opening and closing of channels

Question 12

name 2 channels

Answer 12

chemically gated and voltage gated

Question 13

what does the chemically gated channel respond to

Answer 13

chemicals, neurotransmitters

Question 14

what does the voltage gated channel respond to

Answer 14

change in membrane potential

Question 15

describe local potential

Answer 15

. Local Potential: The receptor/synaptic potential
Either at receptor cell via sensory input
e.g. flavour chemicals on taste buds (receptors) on tongue
Or at a nerve synapse via release of a neurotransmitter
Local change in memb. potential following stimulation.
Magnitude decreases with time and distance.
therefore called a “graded” potential

Question 16

describe action potential

Answer 16

2. Action Potential:
   Stimulus must initially reach a “trigger” potential (- 55mV).
   Large change in membrane potential then spreads down entire length of axon (all or nothing “domino” effect).
   Magnitude is sustained with time and distance.
   =a large wave of depolarization followed by repolarization down the nerve axon

Question 17

movement of action potential involves what channels

Answer 17

voltage gated

Question 18

events of action potentil

Answer 18

Stimulus > Na+ channels open > Na+ rush into the cell >depolarisation > closing of NA+ channels > opening of K+ channels> repolarisation> reaches end of axon > opens ca2+ channels > release of neurotransmitter > opens na+ in next neuron