Strucutre And Funtion Of Sensory, Relay And Motor Neurons

Question 1

The structure of a neuron

Answer 1

The cell body includes a nucleus, which contains the genetic material of the cell.
Branch like structures called dendrites protrude from the cell body. These carry nerve impulses from neighbouring neutrons towards the cell body.
The axon carries the impulses away from the cell body down the length of the neuron. The axon is covered in a fatty layer of myelin sheath that protects the axon and speeds up electrical transmission of the impulse.
The myelin sheath is segmented by gaps called nodes of Ranvier. These speed up the transmission of the impulse by forcing it to jump across the gaps along the axon.
At the end of the axon are the terminal buttons that communicate with the next neuron in the chain across a gap known as the synapse.

Question 2

Electric transmission -

the firing of a neuron

Answer 2

When a neuron is in resting state the inside of the cell is negatively charged compared to the outside.
When a neuron is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur.
This creates an electrical impulse that travels down the axon towards the end of the neuron.

Question 3

Types of neurones

Answer 3

Sensory neurons
Relay neurons
Motor neurons

Question 4

Sensory neurons

Answer 4

These neurons tell the rest of the brain about external and internal environment by processing information taken from one of the five senses.
These carry messages from the PNS to the CNS.
They have long dendrites and short axons.

Question 5

Relay neurons

Answer 5

These neurons carry messages from one part of the CNS to another.
They connect motor and sensory neurons. They have short dendrites and short axons.

Question 6

Motor neurons

Answer 6

They carry signals from the CNS which helps organs, including glands and muscles to function.
They have short dendrites and and long axons.