Question
What does central nervous system consist of ?
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Answer
Central nervous system in human beings is highly ’ developed. It consist of $(a)$ brain $(b)$ spinal cord.
$(a)$ Brain : Brain is the main control centre of the nervous system. It is situated within the skull. It is enveloped by three membranes called meninges. The membranes have a fluid called cerebrospinal fluid between them. The brain is divided in to three regions.
$(i)$ Cerebrum : It is the uppermost and the largest part of the brain. It consists of two cerebral hemispheres. It is responsible for the sensation of pain, temperature, touch, sight, sound, taste and smell. It is also involved in memory, intelligence, thinking and reasoning.
$(ii)$ Cerebellum : It is a small egg shaped organ, placed under the cerebrum at the back of the head. It is involved is muscle coordination and balance of body.
$(iii)$ Medulla Oblongata : It emerges out from the base of the brain and joins the spinal cord to the brain. It is also called the brain stem. It is the regulating centre for swallowing, coughing, sneezing and vomiting.
$(b)$ Spinal cord : It is the continuations of the medulla oblongata. It is like a cord coming out from a hole at the base of the skull, running through the vertebral column. A cross sections of the spinal cord shows two similar halves fused together to form a small canal in the centre called central canal.
It contains cerebrospinal fluid. The $H-$shaped area in central canal is called grey matter, which consist of cell bodies of neurons. The outer portion is white matter which consists of nerve fibres. A part from regulating normal function of the body, many activities of the internal organs like heart, blood vessels and glands are controlled by spinal cord. It also serves as a reflex centre.
$(a)$ Brain : Brain is the main control centre of the nervous system. It is situated within the skull. It is enveloped by three membranes called meninges. The membranes have a fluid called cerebrospinal fluid between them. The brain is divided in to three regions.
$(i)$ Cerebrum : It is the uppermost and the largest part of the brain. It consists of two cerebral hemispheres. It is responsible for the sensation of pain, temperature, touch, sight, sound, taste and smell. It is also involved in memory, intelligence, thinking and reasoning.
$(ii)$ Cerebellum : It is a small egg shaped organ, placed under the cerebrum at the back of the head. It is involved is muscle coordination and balance of body.
$(iii)$ Medulla Oblongata : It emerges out from the base of the brain and joins the spinal cord to the brain. It is also called the brain stem. It is the regulating centre for swallowing, coughing, sneezing and vomiting.
$(b)$ Spinal cord : It is the continuations of the medulla oblongata. It is like a cord coming out from a hole at the base of the skull, running through the vertebral column. A cross sections of the spinal cord shows two similar halves fused together to form a small canal in the centre called central canal.
It contains cerebrospinal fluid. The $H-$shaped area in central canal is called grey matter, which consist of cell bodies of neurons. The outer portion is white matter which consists of nerve fibres. A part from regulating normal function of the body, many activities of the internal organs like heart, blood vessels and glands are controlled by spinal cord. It also serves as a reflex centre.
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