Coordination in animals
Control and coordination
Many processes go on inside the body of a living being, or example, digestion, respiration and growth. These processes do not go on independently. They are related to each other and to the body’s general needs. They are also related to things that occur outside the body. The linking together of the activities of a living being in keeping with the needs of the body as whole, and in response to changes out side of the boy is called coordination.
A few examples will make this clear. When you feel thirsty, you drink water. The simple act of drinking water involves a series of coordinated activities. Your yes located the position of the glass of water on your table. On the basis of this information recorded by your brain, your arm moves and your hand grasp the glass. Then your arm raises it to your lips. Your mouth, pharynx and esophagus act in a coordination fashion to help you drink the water in the glass. The water moves down he alimentary canal and, through another series of coordinated process, reaches the blood flowing in your body to meet the requirement that had originally caused you to feel thirsty.
Thirst is an internal stimulus to which you respond by drinking. A stimulus, as you now, is something that produces a response in an organism. It may be external. It may also be internal (inside the body of the organism). Thirst, pain and hunger are some internal stimuli. You are all ready familiar with response to external stimuli, for example, the sudden withdrawing of the hand upon touching something hot. Such responses too call for coordinated action.
Coordination in animals
What coordinates the activities of a living organism?
Higher animals have specialized cells, called never cells or neurons, which from a net work of communication between the brain and the entire body. This work network is called the nervous system. All vertebrates have a well- developed nervous system, consisting of the brain, spinal cord and a network of nerves.
Lower animals do not posses an elaborate nervous system. For example, hydra just has cells spread throughout the body. Unicellular organisms, like bacteria, Amoeba and euglena have no nervous system, but can still receive stimuli and respond to them. They show response by moving towards or withdrawing from a stimulus. The mechanism behind this is not clearly known. Earthworms have a simple network of nerve cells. The nervous cells clump together at a few points to form ganglia which are masses of nervous tissue. These transmit massages. The nervous system of insects is better developed. It includes a brain, in addition to nerve cells and ganglia. Insects also have eyes and antennae, which are sense organs for receiving stimuli.
Higher animals have another system, called the endocrine system, through which the brain sends messages for the control and coordination of various activities.
The nervous system in human beings consists of the central nervous system, peripheral nervous system and autonomic nervous system.
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