Human Nervous System – An Overview

The nervous system of our body is a vital system since it coordinates the functions of various organs. It is one of the most complex systems of our body. The nervous system is broadly classified into two categories called central nervous system and peripheral nervous system. The central nervous system consists of the brain and spinal cord. The peripheral nervous system is composed of sensory neurons and the neurons that connect them to brain.

Central nervous system (CNS): The central nervous system is the largest part of the nervous system. Two major parts of CNS are the brain and spinal cord. The brain is protected by the skull and spinal cavity protects the spinal cord. The CNS is protected by a three layered protective coating called meninges. The meninges protect the brain like a pad.

Human Nervous System

The Brain

The brain consists of three parts called cerebrum, cerebellum and the brain stem.

Cerebrum: The cerebrum is the largest part of the brain and constitutes about 80 % of brain. The cerebrum consists of right and left hemispheres. The right part is divided into parietal lobes and occipital lobes whereas the left hemisphere is divided into frontal and temporal lobes. The outer layer of brain is called cerebral cortex. All the sensory inputs from different parts of the body reach the cortex. The cerebral cortex is considered as the center of intellectual functions. The cerebral hemispheres are divided into 4 lobes. They are frontal, parietal, temporal and occipital lobes. The right cerebral hemisphere controls the left side activities of body and left cerebral hemisphere controls the right side

Cerebellum:  It is also known as ‘small brain’. It is the cerebellum that coordinates all the muscular movements. It also enable a person to maintain his balance. It is located just above the stem and toward the back of the brain. Cerebellum injury results in movements that are slow and uncoordinated. Damage to the cerebellum can lead to conditions such as the inability to judge distance and when to stop, the inability to perform rapid alternating movements, tendency toward falling, weak muscles etc.

Brain stem (Medulla oblongata): The brain stem connects the spinal cord to the center of brain just below the cerebral cortex. The major part of brain stem is called medulla oblongata. It is the lowest section of the brainstem. Medulla oblongata can regulate the work performed by the heart. Medulla oblongata is the lowest section of brain stem and it is the major section of brainstem which contains centers for regulating the different activities performed by the heart. Thalamus is another important part which acts as a control centre for the sensory center of cerebellum. Hypothalamus is also an important part. 

The main functions of hypothalamus are

1 it controls the temperature regulation, fluid regulation, metabolism etc.
2 Hypothalamus has centers for hunger, thirst, sleep, sexual drive etc.
3 Hypothalamus has centers for subjective feelings, emotions etc
4 It controls the autonomic nervous system which is responsible for maintaining homeostasis
5 The hypothalamus controls the pituitary gland which is the most important endocrine gland in the body.

Author Bio: The Author of this article, Sreejith is writing articles on Biomedical Instrumentation in Electronics and Communications

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