The structure and function of sensory, relay and motor neurons

Question 1

What is a neuron?

Answer 1

Neurons are cells that receive and transmit information to other cells.
It is thought that there are around 100 billion of them in the brain and 1 billion in the spinal cord.
They are an essential part of the communication systems in the body.

Question 2

There are 3 main types of neurons, all of which play a different role in sending and receiving messages:

Answer 2

Sensory
Relay
Motor

Question 3

what is the Nucleus

Answer 3

Contains the genetic material in the form of chromosomes

Question 4

what are dendrites

Answer 4

Tree-like structures that receive messages from other neuronsand transmit electrical stimulation to the soma

Question 5

what is an axon

Answer 5

A long slender projection that conducts electrical impulses away from the cell body

Question 6

what is the cell body/ soma

Answer 6

Where signals from the dendrites are joined and passed on. The soma produces the proteins that the other parts of the neuron, including the dendrites, axons and synapses, need to function properly.

Question 7

what are terminal buttons

Answer 7

Tiny bulblike structures at the end of the axon, which contain neurotransmitters that carry signals across the synapse to other neurons.

Question 8

what is action potential

Answer 8

A short-term change in the electrical potential that travels along a neuron and allows neurons to communicate.

Question 9

Sensory neurons

Answer 9

Sensory neurons inform the brain about the external and internal environment by processing information taken from the senses (from sensory receptors).

Sensory receptors can be found in various parts of the body, e.g. the ears, tongue and skin.

They convert information from these sensory receptors into neural impulses which are then translated into sensations (e.g. heat) when they reach the brain.

Sensory neurons only transmit messages from the body to the brain, not the other way round, therefore they are unipolar

Question 10

Relay neurons

Answer 10

Relay neurons carry messages from one part of the central nervous system to another.

They connect motor and sensory neurons.

Known as multipolar because they both send and receive messages from many sources.

They only exist in the brain and spinal cord.

Question 11

Motor neurons

Answer 11

Motor neurons carry signals from the central nervous system which helps organs, glands and muscles to function.

Also multipolar because they have the capability of both sending and receiving messages.

Motor neurons form synapses with muscles, and control their contractions. When stimulated, the motor neuron releases neurotransmitters that bind to receptors on the muscle and trigger a response (in the form of muscle movement).

Muscle relaxation is caused by inhibition of the motor neuron.

Question 12

Look at diagrams of each neuron

Answer 12

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