nerve impulses

Question 1

is the inside of the axon negatively or positive charged

Answer 1

negative

Question 2

what is resting potential

Answer 2

rate of flow of charge across membrane of axon when an impulse isn’t being transmitted

Question 3

what does polarised mean

Answer 3

negatively charged

Question 4

describe ions in a polarised neurone

Answer 4

-more sodium ions on the outside of axon
-more potassium ions on inside of axon

Question 5

how is the resting potential maintained

Answer 5

• differential permeable membrane
  -sodium/ potassium pump

Question 6

how does the differential permeable membrane mean the resting potential is maintained

Answer 6

• more permeable to the loss of potassium ions
  -due to there being more potassium channels being open than sodium Chanels

Question 7

how do sodium/ potassium pumps maintain resting potential

Answer 7

-actively transport 3 na ions out and 2 potassium in
-requires ATP from respiration
-maintains an electrochemical gradient
- so there’s more sodium ions outside and more k inside for diffusion through membrane

Question 8

describe the sodium potassium pump

Answer 8

actively transported
-3 sodium ions out
-2 potassium in

Question 9

what does a receptor have to do to stimulate action potential and transmit an impulse

Answer 9

-stimulated above its threshold

Question 10

what is action potential

Answer 10

• receptor is stimulated above its threshold
• a change in the potential across axon membrane
  -eg -70 to +40 mV
  -known as depolarisation

Question 11

describe depolarisation

Answer 11

receptor stimulated above its threshold
-potential changes across axon membrane
-70 to +40 mV

-results from an increase in permeability of the axon membrane to sodium ion Chanels

-more scum Chanels open
-positive charge develops