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response&coordinationresponse&coordination Download Notes(Credits to Mustafa Asif) NotesThe 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.
Neurone- 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.
- Motor neurone:
- an effector neurone.
- transmits impulses from the CNS to the effectors.
- Relay neurone:
- connects sensory neurones to motor neurones.
Synapse- 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
| - intelligence
- memory
- voluntary actions
- sensations
| | 2 | hypothalamus | - regulation of body temperature and blood osmotic pressure
- appetite
- emotions
| | 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:
- heartbeat
- respiratory movements
- peristalsis
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Reflex Actions- 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.
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