Neurones

Question 1

Describe structure of sensory neurone

Answer 1

Cell body in centre of axon, dendrites either end, myelinated sheath

Question 2

Describe function of sensory neurone

Answer 2

Carries impulses from receptor to CNS (brain or spinal cord)

Question 3

Describe structure of motor neurones

Answer 3

Cell body at one end with dendrites projecting, myelinated sheath

Question 4

Describe function of motor neurone

Answer 4

Carry impulse from CNS to effectors (muscle/gland)

Question 5

Describe structure of relay neurone

Answer 5

Cell body embedded in axon, dendrites either end, non-myelinated

Question 6

Describe role of the axon

Answer 6

Carries impulses away from cell body

Question 7

Describe how structure of the axon links to its function

Answer 7

• Protected by myelin sheath made up of Schwann cells —> have extra phospholipid, making them impermeable to ions and providing electrical insulation
• Gaps called nodes of Ranvier in myelin sheath —> speed up transmission via saltatory conduction as action potential ‘jumps’ across nodes

Question 8

Describe role of dendrites

Answer 8

Carry impulses towards the cell body, involved in summation, initiate neurone’s action potential

Question 9

Outline process of the reflex arc

Answer 9

Receptor (stimulus) —> Sensory neurone —> Reflex arc —> Motor neurone —> Effector (response)