Action Potential

Question 1

What is an action potential?

Answer 1

The rapid depolarisation and repolarisation of the cell membrane.

Question 2

Describe the depolarisation phase of an action potential.

Answer 2

There will be a rapid influx of sodium ions causing the membrane to become more permeable to sodium. The normal “polarized” state of − 90 millivolts is immediately neutralized.

Question 3

Describe the repolarisation phase of an action potential.

Answer 3

The sodium gates will close and the potassium voltage gates open causing potassium ions to rush out of the cell. The movement of potassium ions causes the cell to become negatively charged.

Question 4

What charge is the intracellular space of a cell?

Answer 4

Negatively charged.

Question 5

What charge is the extracellular space of a cell?

Answer 5

Positively charged?

Question 6

what value of mili volts is measured at the resting membrane potential

Answer 6

-70 mili volts

Question 7

what causes the opening of the voltage-gated sodium channels

Answer 7

if the potential difference increases to negative 55mV.

Question 8

What is the refectory period

Answer 8

A short period following a stimulus during which a nerve cell or muscle fibre cannot be stimulated again.

Question 9

What is hyperpolarisation?

Answer 9

This occurs when too many potassium ions go out of the cell causing the membrane potential to drop lower than the resting membrane potential.