Classification of Nervous System

Nervous System is the most important system which control & integrates the different body functions & maintains the constancy of internal environment despite of extreme change in external environment.

Classification of Nervous System:

1, Central Nervous System – It consists of Brain (cranial part) & Spinal Cord.

2, Peripheral Nervous System – It consists of Cranial nerves (12pairs) & Spinal nerves (31 pairs).

Organs of Nervous System:

1, Brain -                      The enlarged & highly developed mass of nervous tissue contained within the cranium that forms the upper end of the CNS & is continuous below with the spinal cord. It is the controlling organ of the body. It regulates & coordinates body activities.

2, Spinal cord -            the portion of the CNS enclosed in the vertebral column, consisting of nerve cells & bundles of nerves connecting all parts of the body with the brain.

3, Nerves -                   a bundle of fibers that transmit impulses form the brain or spinal cord to the muscles & glands or inward from the sense organs to the brain & spinal cord.

                                    Cranial nerves – the 12 pairs of nerves that arise directly form the brain & leave the skull through separate apertures.

                                    Spinal nerves - the 31 pairs of nerves that leave the spinal cord & are distributed to the body, passing out from the vertebral canal through the spaces between the arches of the vertebrae.

4, Receptor -                present in the inner/outer side of nerve cell that receive impulses.Alfa, Beta, Histamine, Dopamine, etc.

5, Neurotransmitter - chemical substances present in synapse that carry impulses.

e.g. acetylcholine,   Dopamine, Serotonin, etc.

Neuron: Structural & functional unit of nervous system. A neuron consists of Dendrite, Cell body, Axon (nerve fiber), Myelin sheath, Axon terminal.

Process of transmission of impulse:

Dendrite of neuron receive impulse from axon of other neuron through neurotransmitter in the synapse. Then the impulse transmitted to cell body to axon & again to dendrite of other neuron. In this way impulse reaches to the brain. Reversely message from the brain reaches to periphery by this way.

Meninges -                   Thin layer covering brain & spinal cord.

Synapse -                     Synapse is the junction between two neurons where one neuron ends & other neuron begins.

Synaptic cleft -             minute gap in the junction of two neuron.

Common Diseases:

1, Anxiety

2, Depression

3, Hallucination

4, Mania, Phobia

5, Schizophrenia

6, Epilepsy.

7, Meningitis – Infection of meninges by Streptococcus pneumoniae.

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