Chapter 2 - Neurons

Question 1

Neurons consist of….

Answer 1

• the cell body, which contains the nucleus of the cell, and a long axon.
• branches on the cell body called dendrites which receive inputs from other cells (receptors and nerves) and conduct impulses towards the cell body

Question 2

What exactly is an Axon?

Answer 2

• The axon is a long extension of the cytoplasm in a neutron that communicates with the CNS or effector. Some nerves are therefore the longest cells in the body

Question 3

What are neurons?

Answer 3

• Neurons are cells specialised for carrying nerve impulses, so they are often very long.

Question 4

Most axons are covered with…

Answer 4

• myelin sheaths (insulating fatty sheaths)

Question 5

The speed of the nerve impulse is affected by:

Answer 5

• temperature (the speed is increased; it’s always faster in warm blooded animals than cold blooded animals)
• the diameter of the axon (the wider the axon, the quicker the response)
• the myelin sheath (as well as insulating the neuron from neighbouring cells, the presence of the myelin sheath speeds up the nerve impulse - it is able to ‘jump’ from gap to gap along the sheath, making it travel much more quickly.

Question 6

What do Axons do?

Answer 6

• Carries impulses away from the cell body (to other nerves and muscles).