Tissue

• Nervous tissue is a tissue which is specialized for being stimulated and transmission of messages within our body.
• It exerts control over the body’s responses to changing conditions.
• Nervous tissue contains highly specialised unit cells called nerve cells or neurons.
• An individual nerve cell may be up to a metre long.
• The brain, spinal cord and nerves are all composed of the nervous tissue.
• Neurons are excitable cells that are the units of the neural system.
• It is comprised of specialized cells which receive stimuli and conduct the impulses to and from different parts of the body.
• Each neuron has following three parts:
  • The cyton- cell body which contains a central nucleus and cytoplasm with characteristic deeply stained particles,
  • The dendrons- which are short processes arising from the cyton and further branching into dendrites;
  • The axon- which is a single, long cylindrical process of uniform diameter.

How Neuron works?

• The cell body contains a distinct nucleus and has a special kind of granules, called Nissel’s granules in the cytoplasm.
• From the cell body a single long part called the axon and many branched parts called dendrites arise.
• In some nerve cells the axon has a thick white covering called medullary sheath.
• The terminal end of axon is without sheath and branched.
• Each nerve cell receives message through the dendrites and sends them to the axon.

Functions:

• The dendrites receive impulses and the axon takes impulses away from the cell body.

Difference between axon and dendrite: