Sensory Receptors

Question 0

Define the term depolarisation.

Answer 0

Depolarisation is the loss if polarisation across the membrane. It refers to the period when sodium ions are entering the cell making the inside less negative with respect to the outside.

Question 1

Define the meaning of a polarised menbrane.

Answer 1

One that has a potential difference across it. This is the resting potential.

Question 2

State what is meant by a generator potential.

Answer 2

A generator potential is a small depolarisation caused by sodium ions entering the cell.

Question 3

Define the term action potential.

Answer 3

An action potential is achieved when the membrane is depolarised to a value of about +40mV. It is an all-or-nothing response. In the events leading up to an action potential, the membrane depolarises and reaches a threshold level, then lots or sodium ions enter the axon and an action potential is reached.

Question 4

Compare and contrast sensory neurones and motor neurones.

Answer 4

-

Question 5

Suggest why neurones need to contain a large number of mitochondria.

Answer 5

-

Question 6

Why do membranes need special channels for the diffusion of charged ions.

Answer 6

-