KA4- Neurotransmitters and Cells of Nervous System

Question 1

Name and describe the components.

Answer 1

Neurones- receive and transmit electrical signals (nerve impulses)
Glial cells- support neurones and produce myelin sheath.
Dendrites- nerve fibres which receive nerve impulses and pass them towards a cell body.
Cell body- contains the nucleus and most of the cytoplasm. It is the control centre of cell metabolism.
Axon- a single nerve fibre that carries nerve impulses away from a cell body.

Question 2

Describe the structure and function of myelin sheath.

Answer 2

Axons are surrounded by a myelin sheath which insulates the axon and increases the speed of impulse conduction.

Question 3

What is myelination?

Answer 3

Myelination is the process by which myelin develops round axon fibres.

Question 4

Compare the myelin contents of adults and infants.

Answer 4

Myelination is not complete at birth and so over the first two years of life many more neurones are myelinated. As a results, responses to stimuli in the first two years of life are not as rapid or co-ordinated as those of an older child or adult.

Question 5

How is myelin sheath destroyed?

Answer 5

Certain diseases destroy the myelin sheath causing a loss of co-ordination. Diseases such as polio and multiple sclerosis.