Question 2
Compare the following:
(a) Central neural system (CNS) and Peripheral neural system (PNS)
(b) Resting potential and action potential
(c) Choroid and retina
(a) Central neural system (CNS) and Peripheral neural system (PNS)
| 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. |
(b) Resting potential and action potential
| 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. |
(c) Choroid and retina
| 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. |
