- This chapter explains the process by which different living organisms control and coordinate different life processes and give response to different stimulus.
- This chapter explains the control and coordination in animals specially human beings through nervous and hormonal system. It also explains the types, structure and function of neurons.
· All living organisms (plants and animals) respond and react to changes in the environment around them. The changes in the environment to which the organisms respond and react are called stimuli. These stimuli can be light, heat, cold, sound, smell, taste, touch, pressure, water, and force of gravity, etc. Living organisms respond to any stimulus generally by movement.
· The response of organisms to a stimulus is usually in the form of movement of their body part.
Ex: If we touch a very hot utensil accidentally, we quickly pull our hand away from the hot utensil. Heat is the stimulus and we reacts by moving our hand away from the hot utensil.
· The response to stimulus is a characteristic property of the living organisms.
· The various organs should coordinate with each other in order to provide proper reaction to the stimulus.
· The working together of the various organs of an organism in a systematic manner so as to produce a proper response to the stimulus is called coordination.
· The method of reacting to stimuli, control and coordination is different in plants and animals.
Coordination in Animals
· Multicellular animals (except sponges) have specialized cells called neurons to respond to stimuli and coordinate their activities.
· A system made up of nerve cell is called nervous system.
Ex: Hydra is a simple multicellular animal. The nervous system of Hydra consists of a network of nerve cells joined to one another and spread throughout its body.
· The control and coordination in higher animals called vertebrates (including human beings) takes place through nervous system as well as hormonal system called endocrine system.
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