10 March 2014

# 86 The human nervous system

The human nervous system is made up of two parts: 

  • Central nervous system (CNS) - brain and spinal cord: role of coordination
  • Peripheral nervous system - nerves: connect all parts of the body to the CNS. 
Together, they coordinate and regulate body functions.
Sense organs are linked to the peripheral nervous system. They are groups of receptor cells responding to specific  stimuli: light, sound, touch,  temperature and chemicals. When exposed to a stimulus they generate an electrical impulse which passes along peripheral nerves to the CNS, triggering a response. 

Peripheral nerves contain sensory and motor neurones (nerve cells). 

transmit nerve impules
Sensory neurone
sense organs  à CNS

Motor neurone
CNS  à  effectors
(muscles or glands)

Motor and sensory neurones are covered with a myelin sheath, which insulates the neurone to make transmission of the impulse more efficient. 

The cytoplasm (mainly axon and dendron) is elongated to transmit the impulse for long distances.

Sensory neurone
Motor neurone
Cell body
Near end of neurone, in a ganglion (swelling) just outside the spinal cord
At start of neurone, indise the grey matter of the spinal cord
Present at end of neurone
Attached to cell body
Very short
Very long
Very long

Fun fact: The human nervous system runs on electrical impulses that travel close to the speed of light.

Sample question and answer

Question   Figure above shows a type of neurone. Name this type of neurone and state a reason for your choice.  [ 2 marks]

Answer  Name: motor neurone. 

               Reason: It has a cell body, the cell body is at the end of the cell. 

Video: The Human Nervous System

Video: The Spinal Cord 

Video: Human Body Nervous System


  1. Theres a mistake in the table, you switched up the function of the motor neurone and the sensory neurone, Please fix that thank you! :)

  2. I think there is a mistake in the reason for the answer, can you fix it please?

    1. Isn't it the start rather than the 'end'? Sorry for the trouble :0

    2. Hi, I think it's more logical to talk about the ends (extremities) of the cell rather than its start and end. It's hard to say where does a cell start and where does it end. Anyway, the phrase have been taken from the revision book, not my own one. Thanks for discussing. Cheers.

  3. thank you so much ........ hope all the information is accurate cause i am writing a test on bio