The structure and function of neurons

Question 1

Neurons

Answer 1

Specialised cells designed for the transmission of information throughout the body through electrical impulses

There are thought to be as many as 100 billion neurons in the brain and over 1 billion in the spinal cord

Question 2

3 types of neuron

Answer 2

Sensory
Relay
Motor

Question 3

Sensory neuron

Answer 3

Send information to the brain regarding the senses through nerve impulses

They can only transmit messages

Sensory receptors -> CNS
eg eyes, ears

When they reach the brain they are translated into sensations

Some don’t reach the brain, stop at SC= quick reflexes

They have long dendrites and, relatively, short axons

The cell body is usually to the side of the cell

Question 4

Relay neurons

Answer 4

They connect the sensory neurons to the motor neurons and allow them to communicate

Lie wholly in the brain and SC

They can both transmit and receive messages

They have short axons and short dendrites

Question 5

Motor neurons

Answer 5

Conduct signals from CNS to effector organs

When stimulated the motor neuron releases neurotransmitters that bind to the receptors and form synapses with muscles and control their contractions .

They have short dendrites and, relatively long axons

They can both transmit and receive message