Note on Introduction to Nervous System

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The system that receives and transmits the stimulus, to and from the brain is called the nervous system.

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Neuron:

The cell that transmits the message one part of the body to the other part is called nerve cell or neuron. A neuron is divided into three parts cell body, axon and dendrites. Cell body is the main cellular part of the neuron. All the protein synthesis occurs in cell body. Axon is the longest extension arising from thecell body. It carries electrical impulse away from the cell body. Sometimes the neuron has insulation sheet called myelin associated with it. Those neurons are called myelinated nerve cell. It increases the velocity of the impulse carried by the nerve. These type of neuron found in theperipheral nervous system. Dendrites are the short but numerous extension arising from the cell body. They carry impulse from other neurons into the cell body.

Types of Neuron:

There are three types of neuron on the basis of work performed by them. They are

  1. Afferent or Sensory nerve: They carry impulses from various parts of the body to the brain or spinal cord.
  2. Efferent or motor nerve: They carry impulses from the brain or spinal cord to different parts of the body. They are of three types:
  • Motor nerves enter into muscle.
  • Secretary nerves enter into various glands.
  • Vasomotor nerves control blood vessels.
  1. Mixed nerve: Sometimes axons of both motor and sensory neurons form a nerve which is called motor nerve. All the spinal nerves are mixed types.

Parts of Nervous System:

Human nervous system is divided into three parts. They are:

  1. Central Nervous System (CNS): Consist of brain and spinal cord
  2. Peripheral Nervous System (PNS): Consist of cranial nerves (nerves arising from brain) and peripheral nerves (nerves arising from spinal cord)
  3. Autonomic nervous system (ANS): consist of ganglia and subganglia in organs.

  • The system that receives and transmits the stimulus, to and from the brain is called nervous system.
  • The cell that transmits the message one part of the body to the other part is called nerve cell or neuron.
  • There are three types of neuron on the basis of work performed by them. They are afferent or sensory nerve, efferent or motor nerve and mixed nerve.

 

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Very Short Questions

The main components of nervous system are brain, spinal cord and nerves.

Nervous system can be divided into two groups-
a. Central nervous system with brain and spinal cord
b. Peripheral nervous system with different types of neurons.

There are three different types of neuron. They are:
a. Sensory neuron: It takes the impulses from sense organs (receptors) to the central nervous system.
b. Motor neuron: It takes the impulses from the central nervous system to the muscles (effecters).
c. Inter neuron: It links sensory neuron to motor neuron.

The nerve cell bears branches, one of which is longer and is protected by medullary sheath is called axon.

Dendrite is defined as a small branch of the nerve cell which carries stimulation and reaction towards the spinal cord.

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  • The cells that transmit the message form one part of the body to other are known as ______.

    Neurons


    Mixed nerves


    Dendrites


    Spinal cord


  • Which of the following carry impulses from various parts of the body to the brain or spinal cord?

    Efferent nerves
    Afferent nerves
    Mixed nerves
    Can't say
  • Which of the following is a long tube like structure that arises from neuron?

    Axon
    All of above
    Cell body
    Dendrites
  • ______ sends most of the impulses to the dendrites of another neuron.

    Nerve fibers


    Neuron


    Nucleus


    Axon


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Define ganglia.


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