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The Nervous SystemThe nervous system of a mammal consists of:
- The central nervous system (CNS) comprising the brain and the spinal cord.
- The peripheral nervous system (PNS) comprising the cranial nerves, spinal nerves and sense organs.
- A neurone is a nerve cell.
- A nerve fibre is a long protoplasmic extensions of the cell body of a neurone. It serves to transmit impulses.
- A nerve is a collection of nerve fibres.
Types of neurons
- Sensory neurones:
- a receptor neurone,
- transmits impulses from the sense organ (receptor) to the CNS.
- an effector neurone.
- transmits impulses from the CNS to the effectors.
- connects sensory neurones to motor neurones.
- A synapse is a junction between two neurones.
- A dendron transmits impulses towards the cell body of a neurone.
- An axon transmits impulses away from the cell body of a neurone.
| || Parts of mammalian brain|| Functions|
| 1|| cerebrum|
- voluntary actions
| 2|| hypothalamus|
- regulation of body temperature and blood osmotic pressure
| 3|| pituitary gland|
- secretes a number of hormones
| 4|| optic lobes|
- sight and movement of eyeball
| 5|| cerebellum|
- muscular coordination
- body balance
| 6|| medulla oblongata|
- involuntary actions, eg:
- respiratory movements
- Reflex actions involve messages being transmitted from the sensory neurone to the motor neurone without involving the conscious part of the brain.
- A reflex arc is the shortest pathway by which impulses travel from the receptor to the effector in a reflex action.