Topic 8

Question 1

Explain how passive potassium channels are involved in establishing the resting potential of an axon

Answer 1

Passive channels allow K+ ions to move down diffusion gradient, which means that they are moving out of the axon. Movement through the channels is reduced by the negative charge inside the axon. Therefore there is no net movement of K+ at resting potential

Question 2

What are the three types of neurone?

Answer 2

Sensory that transmit impulses from receptors to CNS
Relay that transmit impulses between sensory and motor
Motor that transmit impulses from CNS to effectors

Question 3

Describe the structure of sensory neurones

Answer 3

One long dendron that transmits impulses from the receptor to the cell body.
One short axon that carries the impulse from the cell body to the CNS.
The cell body is located in the middle of the neurone

Question 4

Describe the structure of motor neurones

Answer 4

Many short dendrites that carry impulses from the CNS to the cell body.
One long axon that carries nerve impulses from the cell body to effector cells

Question 5

Describe the structure of relay neurones

Answer 5

Many short dendrites that carry impulses from sensory neurones to the cell body.
One axon that carries impulses from the cell body to motor neurones