Class 10 Biology Control and Coordination Nervous system in animals

Nervous system in animals

  • The nervous system is concerned with receiving of stimuli from the external and internal environment of the body.
  • The action of nervous system are performed by highly specialized cells called neurons which can receive the messages and conduct them to the brain where the they are interpreted and then returned to the concerned parts of the body.
  • The nervous tissue is made up of an organized network of nerve cells which are specialized for conducting electrical impulse form one part of the body to another.
  • Impulse is the signal transmitted along a nerve fibre.
  • Neurons or nerve cells are the structural ad functional units of nervous system.

Structure of neuron

  1. I) Cell body- it is rich in cytoplasm and has a spherical nucleus.
  2. II) Dendrites- short and branched tips of nerve cell stretching out from the cell body and detect the information of the environment.

 III) Axon- long cylindrical structure arising from the cell body. The information from the environment travels through the axon and reaches the next nerve to reach the brain.

  1. IV) Nerve ending- branched ending of axon which helps in neurotransmission

Fig. Neuron

Neurotransmission

  • Neurotransmission is the travelling of impulse to the brain through the nerve cells.
  • Impulse is the signal transmitted along a nerve fibre.
  • Any change in the environment is detected by the specialized tips of nerve cells called dendrites in the form of message.
  • Dendrites are present in the sense organs.
  • The message acquired sets off a chemical reaction which creates an electrical impulse.
  • Electrical impulse travels from the dendrite to the cell body and then along the axon to the nerve endings.
  • At the nerve endings, the electrical impulse sets off the release of chemicals.
  • Synapse is the gap between two nerve cells, across which impulses pass to reach the next nerve cell.
  • The chemicals released at the nerve endings, cross the synapse and start a similar electrical impulse in a dendrite of the next neuron and the process goes on.
  • A similar synapse allows delivery of impulses from neurons to other types of cells such as muscle cells or glands.

Fig.chemicals released at the nerve endings

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