Brain:

Human brain is contained in skull. It has three major parts.
i) The Cereberum ot bigger brain
ii) The Cerebellum or Smaller brain
iii) Medulla Oblongata or hind brain

The cereberum constitutes the major volume of brain. It consists of two large masses of nervous material known as cereberal hemispheres. Human consciousness, thought, emotions, sight, will, hearing, sensation of pain, memory and speech are centere in the creberum. Some parts of it also control motor nerves, operating the arms and legs.

The cerebellum or the smaller brain is related with the coordination of action of nerves and muscles. In this way movements of body are manged. Medulla or hind brain contains the centres for reflex actions in addition to automatic movements such as breathing and walking.

Reflex Action:

- Reflex actions are the responsed to environmental changes both internal and external and are immediate or automatic and are without intervention of will.
- These reflexes amy be simple or conditioned e.g. watering of mouth on seeing or smelling of food.
- Simple reflexes are inborn, inherited or unlearnt responses to stimuli.
- The structural and functional basis of simple reflex is called reflex arc.
- Impulses are carried from receprtors to sensory neurons to CNS from where they are passed on via motor neurons to the effectors for necessary response.