NERVOUS SYSTEM -BIOLOGY- TNPSC,TET,RRB,SSC SCIENCE (GK) STUDY MATERIAL

NERVOUS SYSTEM
Its unit is Neuron
Largest cell of our body is neuron only.
Types: A. Central nervous system: Brain + spinal cord
B. Peripheral Nervous system : Nerves
C. Autonomic Nervous system: Sympathetic, Parasympathetic nervous system.

A. CENTRAL NERVOUS SYSTEM
Brain is covered by 3 layers Meninges

  1. Durameter (toughest)
  2. Arachnoid mater
  3. Plamater
    Cerebrospinal fluid is filled between the meninges.
    (a) Cerebrum
    Grey matter controls activities such as speech, taste, smell, hearing (conscious activities)
    (b) Cerebellum
    Concerned with equilibrium of the body and brings about co-ordination and control of muscular activities of the body.
    (c)Medulla Oblongata
    Lowest part of the brain and is connected to the spinal cord.
    Controls the involuntary actions (respiration, heart beat, flow of blood in blood vessels, secretion of glands, etc)
    REFLEX ACTION
    First discovered by Marshal Hall.
    Co-ordinated by spinal cord
    CONDITIONAL REFLEX
    First shown by Payloy on dog
    It is controlled by the cerebrum
    PERIPHERAL NERVOUS SYSTEM
    Composed of Cranial nerves and spinal nerves.
    Cranial are 12 pairs while spinal are 31 pairs.
    Trigeminal : Mixed
    Facial : Mixed
    Vagus : Mixed(largest) AUTONOMOUS NERVOUS SYSTEM
    Not under voluntary control.
    Controlled by Central Nervous system.

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