2- neurons

Question 1

define neurons

Answer 1

specialised nerve cells that move electrical impulses to and from the CNS

Question 2

describe the structure of a neuron

Answer 2

• cell body (controls centre of the neuron)
• nucleus (genetic material)
• dendrites (receive action potential from other neurons)
• axon (long fibre that carries electrical impulse from cell body to axon terminal)
• myelin sheath (made up of Schwann cells, insulating layer that protects axon and speeds up transmission)
• nodes of Ranvier (gaps in myelin sheath which speed up electrical impulse)

Question 3

describe a sensory neuron

Answer 3

• found in receptors
• carry electrical impulses from sensory receptors to CNS via the PNS
• convert info from receptors to electrical impulses which are converted to sensations in the brain so the body can react
• some terminate at the spinal chord allowing reflexes to occur quickly

Question 4

describe a motor neuron

Answer 4

• found in CNS

- send electrical impulses via axons to glands/muscles (effectors)

Question 5

describe a relay neuron

Answer 5

• found in the CNS
• connect sensory neurons to motor neurons
• during reflex arc they are involved in an analysis of the sensation and decide how to respond