Compare the following:
(a) Central neural system (CNS) and Peripheral neural system (PNS)
(b) Resting potential and action potential
(c) Choroid and retina

Central neural system

Peripheral neural system

1.

It is the main coordinating centre of the body.

1.

It is not the main coordinating centre of the body.

2.

It includes brain and spinal cord.

2.

It includes cranial and spinal nerves that connect central nervous system to different parts of the body.

Resting potential

Action potential

1.

It is the potential difference across the nerve fibre when there is no conduction of nerve impulse.

1.

It is the potential difference across nerve fibre when there is conduction of nerve impulse.

2.

The membrane is more permeable to K⁺ ions than to Na⁺ ions.

2.

The membrane is more permeable to Na⁺ ions than to K⁺ ions.

Choroid

Retina

1.

Choroid is the middle vascular layer of eye.

1.

Retina is the innermost nervous coat of eye.

2.

It contains numerous blood vessels that provide nutrients and oxygen to retina and other tissues.

2.

It contains photoreceptor cells, rods and cones that are associated with twilight and colour vision respectively.