Tuesday, 7 April 2020

NERVOUS SYSTEM

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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