Neurones

Question 1

What are neurones?

Answer 1

Specialised cells adapted to rapidly carrying electrochemical charges called nerve impulses from one part of the body to the other.

Question 2

What is a mammalian neurone made up of?

Answer 2

A cell body
Dendrons
An axon
Schwann cells
A myelin sheath
Nodes of Ranvier

Question 3

What is a cell body?

Answer 3

Contains a nucleus and large amounts of rough endoplasmic reticulum.
This is associated with the production of proteins and neurotransmitters.

Question 4

What are dendrons?

Answer 4

Small extensions of the cell body which subdivide into smaller branched fibres, called dendrites, that carry nerve impulses towards the cell body.

Question 5

What is an axon?

Answer 5

A single long fibre that carries nerve impulses away from the cell body.

Question 6

What are Schwann cells?

Answer 6

These surround the axon protecting it and providing it with electrical insulation.
They also carry out phagocytosis (the removal of cell debris) and in nerve regeneration.
Schwann cells wrap themselves around the axon many times, so that layers of membrane build up around it.

Question 7

What is the myelin sheath?

Answer 7

Forms a covering to the axon and is made up of the membranes of Schwann cells.
The membranes are rich in the lipid myelin.
Myelinated neurones transmit nerve impulses faster than unmyelinated neurones.

Question 8

What is Node of Ranvier?

Answer 8

Gaps between adjacent Schwann cells where there is no myelin sheath.

Question 9

The three neurones can be classified according to their function…
- Sensory

Answer 9

Sensory- transmit nerve impulses from a receptor to an intermediate or motor neurone.
They have one dendron that carries the impulse towards to the cell body adn one axon that carries it away.

Question 10

The three neurones can be classified according to their function…
- Motor

Answer 10

Motor- transmit nerve impulses from an intermediate or sensory neurone to an effector, such as a gland or muscle.
They have a long axon and many short dendrites.

Question 11

The three neurones can be classified according to their function…
- Intermediate/ Relay

Answer 11

Intermediate/ Relay- transmit impulses between neurones for example, between sensory to motor.
They have numerous short processes.