Nervous system: Definition and classification

Nervous system:

The nervous system controls the function of all other systems such as Human behavior, Intellectual ability, the release of different types of information, storage of memory, etc.

The nervous system can be classified into two classes-

1. Peripheral Nervous System (PNS)
2. Central Nervous System (CNS)

PNS can be subdivided into two classes-

• Somatic nervous system
• Autonomic nervous system

CNS consists of the Brain and Spinal cord. The somatic nervous system contains the spinal nerve, cranial nerve.

Nervous Tissue:

Nervous tissue is the basic one of the nervous system. The structural and functional unit is a neuron that consists of the axon, dendrite, and cell body. The long process of a neuron is called an axon and the short process is called a dendrite. The cell body contains mitochondria, Golgi body, nucleus, etc. parts which are available in other cells and especially contain nissl granules and neurofibrils. 

Nissl Granules:

Nissl granules are granular substances present in the cytoplasm. They are basophilic in nature and chemically they are ribose nucleoprotein containing iron. They help in the conduct of nerve impulses.

Neurofibrils:

Neurofibrils are fine filaments like electric wire which transmit impulses and present in axons, dendrite,s and in cell bodies. They help in the conduct of nerve impulses.

Neuroglial Cell:

Neuroglial cells are supporting cells produce from neuroglia. 

               Physiological function:

                                  -Supporting and nutrition supply.

              Classification:

   Neuroglial cells can be divided into five classes. They are-

1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Ephendyma
5. Schwann Cell