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Co-ordination in human beings:


In human beings, different activities are taking place simultaneously. They need to be co-ordinated efficiently and effectively. The co-ordination of different bodily activities are controlled by two mechanisms, namely – (a) nervous control and (b) chemical control. The components of the human nervous system are brain and the nerves.

The human nerves system:
The nervous system can be divided into:
(i)            the central nervous system or CNS
(ii)           the peripheral nervous system or PNS and
(iii)          the autonomic nervous system or ANS

The central nervous system comprises of the brain and the spinal cord and regulates all activities of the body. The peripheral nervous system includes all the nerves. The nerves form a network and spread throughout the body. They are instrumental in connecting all parts of the body to the central nervous system. The autonomic nervous system comprises of all the nerves present in the involuntary organs like heart, stomach, lungs, etc.

       On the basis of their function, the nerves are categorized as afferent and efferent nerves. Afferent nerves carry impulses from the sensory organs to the brain. Efferent nerves carry impulses from the brain to the sensory organs.

The nerves are composed of neurons and neurogila. The neurons are specialized cells capable of creating and transmitting electromechanical impulses. The neurogila are supportive cells which assist the neurons in their function.

         To determine whether the object is hot or cold we usually touch them. How do we detect that we are touching a hot or cold object?

All the information from our environment is picked up by the specialized tips of dendrites of a neuron. It sets off a chemical reaction producing an electrical impulse which travels from the dendrite to the cell body and from there, though the axon(nerve fiber) to its end. At the end of the first axon, the electrical impulse induces the release of some chemicals. These chemical produced go across the small gap(synapse) of 2-20 nanometre (nm) between the neurons and starts a similar electrical impulse in the dendrite of the next neuron. This is the procedure by means of which the impulses travels in the body from the neurons and are delivered to the muscle cells or glands.

        When an action or movement has to be brought about, the muscle tissue does the final job. The muscle cells should move to enable work to be done. The movements at the cellular level takes place when the cells change their shape, so that they shorten. Muscle cells possess special kind of proteins which are capable of bringing about change in their shape and make the cell capable to respond to the nervous electrical impulses.
We can infer that the nervous tissue is composed of a highly organized network of neurons capable of transferring information in the form of electrical impulses from one part of the body to another.

        In accordance to their functions, the neurons are classified into three groups namely –sensory neurons, motor neurons and association neurons. Sensory neurons conduct impulses from the sense organs to the brain and spinal cord. Motor neurons conduct impulses from the brain and spinal cord to the effector organs like muscles and glands. Association neurons perform intergrative functions of the nervous system.