Chapter 7. Control and Coordination
All living organisms respond to various stimuli like heat, light, cold, touch, pressure etc.
Example : Withdrawal of hand on touching a hot object.
Control and Coordination in Animals:
It is brought about in all animals with the help of two main systems
(a) Nervous System
(b) Endocrine System
Functions of Nervous System
(i) To receive the information from environment
(ii) To receive the information from various body parts.
(Stimuli → Response)
(iii) To act accordingly through muscles and glands.
1. Stimulus : Any change in environment to which the organisms respond is called stimulus. E.g., touching a hot plate.
2. Response : The reaction of our body to a stimulus. E.g. withdrawal of our hand on touching hot plate.
3. Receptors : Are specialised tips of some nerve cells that detect the information from the environment.
Type of Receptors :
(i) Photo receptor : for vision (Eye)
(ii) Phono receptor : for hearing (Ear)
(iii) Gustatory receptor : for taste (Tounge)
(iv) Olfactory receptor : for smelling (Nose)
(v) Thermo receptor : for for feeling heat (skin)
These receptors are usually located in our sense organs, such as the inner ear, the nose, the tongue, and so
Nervous Tissue: nervous tissue is made up of an organised network of nerve cells or neurons, and is specialised for conducting information via electrical impulses from one part of the body to another.
Nervous cell (neuron) : The unit of nervous tissue is called nevous cell or neuron.
Structure of neuron:
Functions of nervous cell or neuron:
Nervous cell or neuron is specialised for conducting information via electrical impulses from one part of the body to another.
The parts of nervous cells:
(i) Dendrite : Where informations are acquaired at the end of the dendritic tips of a nerve cell.
(ii) From Dendrite to cytoplsm : Here the the impulse travels from the dendrite to the cell body, and then along the axon to its end.
(iii) Axon : At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar electrical impulse in a dendrite of the next neuron.
Propagation of informations through nerves :
All informations to our brain that delivers the informations that are acquaired at one end of dendritics of the nerve cell and sets off a chemical reaction that creates an electrical impulse. This impulse travels from the dendrite to the cell body, and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar
electrical impulse in a dendrite of the next neuron.Such informations are transmitted from one place to another place of the body.
Synapse: The space between two neurons is called synapse.
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