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Control and Co-ordination

Human Neural System

Neural system

  • It provides rapid coordination among the organs of the body.
  • The coordination may be in the form of electric impulses, which is quick and short-lived.

Neurons

  • Neurons are structural and functional units of nervous system.
  • Structure of neuron
  1. Cell body – Contains Nissl’s granules
  2. Dendrite – Conducts messages towards cell body
  3. Axon – Conducts messages away from cell body
  • Neurons are of three types:
  1. Unipolar
  2. Bipolar
  3. Multipolar
    • Axons are of two types:
    1. Myelinated nerve fibre
        • Fibre is coated with myelin sheath, which is impermeable to ions. Schwann cells enveloped the myelin sheath.
        • The place where myelin sheath is not present on the myelinated nerve fibre is called node of Ranvier.
        • Conduction of nerve impulse is from node to node in a jumping manner. Hence, the conduction is fast.
        • Found in spinal and cranial nerves
    1. Non-myelinated nerve fibre
      • Fibres are not coated by myelin sheath.
      • Conduction of nerve impulse occurs along the whole length of nerve fibre. Hence, the conduction is slow.
      • Found in autonomous and somatic neural systems

 

Parts of the nervous system

  • Human nervous system divided into- central nervous system (CNS) and peripheral nervous system (PNS)
  • CNS consists of the brain and spinal cord 
  • PNS consists of the nerves that connects the CNS to different parts of the body
  • The Brain, spinal cord, and nerves are the important parts of the nervous system


Brain

  • The brain is enclosed in a bony box called the cranium and spinal cord is protected by vertebral column.
  • The brain and spinal cord are externally covered by protective covering called meninges.
  •  It is made up of three layers namely duramater (outer layer), arachnoid (middle layer), piamater …

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