CONTROL AND COORDINATION:

Nervous system is a system of highly specialized nerve cells , nerve fibres and organs that continue and control the activities of different parts of the body. This is done by converting external and internal stimuli of environmental changes into the form of electrical impulse( a process called transduction) and transmit them into a specialized called effectors(muscles, glands etc.) to react accordingly.

Between the receptors and effectors are the conducting cells of nervous system, called neurons. Neurons are the structural and functional unit of the nervous system that forms a complex network of communications by spreading throughout the organism.

Reflex action:(Marshal Hull, 1833) is an immediate involuntary action of any organ or part of the body in response to the particular stimulus. The function or action occurs immediately, without the involvement of will or consciousness.

Reflex arc: The nervous pathway taken by nerve impulse in a reflex action is called reflex arc.

Examples of reflex action:

1) Blinking of an eyelid when a moving object approaches the face.

2) Sneezing is a reflex action to the stimuli in nose.

3) Salivation occurs at the sight of food.

4) An  immediate removal of hand when it touch hot bodies.

Importance of reflex action:

1) It enables the animal to respond immediately to a harmful stimuli so that the no harm is caused to it.

2) It relieves the brain of too much work as the responses of routine nature take the form of reflex actions. If the animal is to exercise its will every time a wave of peristalsis occurs in the intestine, then the brain would soon become exhausted.

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