Action Potential

Question 1

Stages of action potential

Answer 1

• depolarisation
• repolarisation
• hyperpolarisation
• return to resting potential

Question 2

Depolarisation

Answer 2

• Stimulus causes gated Na+ channels to open causing permeability of Na+ to increase
  -Na+ diffuse down electrochemical gradient into axon, making inside of the neurone less negative
• if stimulus is great enough and threshold value is reached, action potential occur
• more Na+ channels open, membrane becomes depolarised

Question 3

Repolarisation

Answer 3

• K+ channels open/Na+ channels close
• permeability to k+ increase
• k+ diffuse out of neurone down electrochemical gradient
• neurone becomes more negative compared to outside

Question 4

Hyperpolaristaion

Answer 4

• K+ channels slow to close
• neurone more negative than the outside

Question 5

What is the refractory period

Answer 5

The Period where another action potential cannot take place

Question 6

Why is refractory period important

Answer 6

• So action potential don’t overlap
• ensures unidirectional impulse
  -limits frequency of impulse transmission
• produces discrete impulses

Question 7

All or nothing principle

Answer 7

Any stimulus that causes the membrane to reach threshold potential will generate an action potential

Question 8

3 factor that affect speed of conductance

Answer 8

• myelin sheath
• axon diameter
• temperature

Question 9

How does axon diameter affect speed of conductance

Answer 9

Greater diameter = faster
- less resistance to flow of ions
- less leakage of ions, easier t maintain membrane potential

Question 10

How does temp affect seed of conductance

Answer 10

Higher temp = faster
- faster rate of diffusion
- faster rate of respiration = more ATP for active transport to re-establish resting potential

Temp to high = denature

Question 11

Stats test used to determine wether a factor has a significant effect on the speed of conductance

Answer 11

T test - Comparing means of continuous data