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Animal Tissues - Nervous Tissue

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Nervous Tissue

Nervous tissues consist of neurons and neurological cells. The neuron is an excitable cell and a main component of the neural system. The neuroglia forms the rest of the neural system, which makes up double the volume of neural tissue in the human body. Nervous tissues have the greatest control over the body’s responsiveness to changing conditions.

Structure of a Neuron

  • It is an elongated cell with a Cell Body that consists of some branch-like structure called Dendrites.

  • There is a Nucleus present in the center of the cell body.

  • The Nerve Endings of the cell are connected with the cell body via Axon.

  • A nerve cell can be up to 1 m long.

The Structure of Neuron:

1. Dendrites

  • They are tree-like extensions (highly-branched) at the beginning of a neuron.
  • They increase the surface area of the neuron.
  • They receive chemical signals from different neurons of the body.
  • They then convert these chemical signals into electrical signals and pass them to the neuron cell body.
  • A neuron can have a single dendrite or multiple dendrites

2. Cell Body

  • Also called Soma.
  • The main function of the cell body and nucleus of the neuron is to maintain the functionality of the cell.
  • It does not play an active role in the transmission of the signal.
  • It produces proteins that are required by different parts of the neuron to work properly.
  • It contains different cell organelles such as mitochondria, Golgi apparatus etc that perform various functions of the cell.

3. Axon

  • Neurons have one axon in general.
  • It is a long structure that connects the cell body to the terminals and it also connects with other neurons, cells and organs of the body through nerve terminals.
  • It allows in fast transmission of signals. The larger the diameter of the axon the faster it will transmit signals.
  • It is covered with a special insulating substance called myelin. It helps in rapid transmission of signals.

4. Schwann Cells (OLYMPIAD)

  • The Myelin sheath that covers the axon is produced by Schwann cells.
  • The Myelin sheath keeps the signal intact

notes

Nervous tissue:

  • Highly specialized for receiving stimulation and then transmitting it very rapidly from one place to another within the body.

  • The brain, spinal cord, and nerves are all composed of the nervous tissue.

  • The cells of this tissue are called nerve cells or neurons.

  • Many nerve fibres bound together by connective tissue make up a nerve.

  • Each neuron consists of a cell body and axon.

    • Cell body - consists of the nucleus and cytoplasm. It also has dendrites (branchings).

    • Axon - can be myelinated or unmyelinated depending on the presence or absence of mylien sheath which helps in the insulation of nerve fibre( like a rubber covering to copper wires).

    • Nerve ending - the end of a neuron through which impulse is released.

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