Nervous tissue

Nervous issue is tissue that is composed of neurons, and other cells seen in the nervous system.

Where is nervous tissue found?

The nervous tissue is found in the brain, spinal cord, and nerves.

Neuron under microscope

Functions of nervous tissue

The nervous tissue is responsible for coordinating and controlling many body activities. It stimulates muscle contraction, creates an awareness of the environment, and plays a major role in emotions, memory, and reasoning. To do all these things, cells in nervous tissue need to be able to communicate with each other by way of electrical nerve impulses.

Different cells in nervous tissue

The cells in nervous tissue that generate and conduct impulses are called neurons or nerve cells. These cells have three principal parts: the dendrites, the cell body, and one axon.

• The main part of the cell, the part that carries on the general functions, is the cell body.
• Dendrites are extensions, or processes, of the cytoplasm that carry impulses to the cell body.
• An extension or process called an axon carries impulses away from the cell body.

Complete neuron cell diagram

Neurons

Neurons, or nerve cells, carry out the functions of the nervous system by conducting nerve impulses. Each neuron has three basic parts: cell body (soma), one or more dendrites, and a single axon.

Cell Body

In many ways, the cell body is similar to other types of cells. It has a nucleus with at least one nucleolus and contains many of the typical cytoplasmic organelles. It lacks centrioles, however. Because centrioles function in cell division, the fact that neurons lack these organelles is consistent with the amitotic nature of the cell.

Dendrites

Dendrites and axons are cytoplasmic extensions, or processes, that project from the cell body. They are sometimes referred to as fibers. Dendrites are usually, but not always, short and branching, which increases their surface area to receive signals from other neurons.

Axon

An axon may have infrequent branches called axon collaterals. Axons and axon collaterals terminate in many short branches or telodendria. The distal ends of the telodendria are slightly enlarged to form synaptic bulbs. Many axons are surrounded by a segmented, white, fatty substance called myelin or the myelin sheath. Myelinated fibers make up the white matter in the CNS, while cell bodies and unmyelinated fibers make the gray matter. The unmyelinated regions between the myelin segments are called the nodes of Ranvier.

In the peripheral nervous system, the myelin is produced by Schwann cells

Neuroglia

Neurogliacells do not conduct nerve impulses, but instead, they support, nourish, and protect the neurons. They are far more numerous than neurons and, unlike neurons, are capable of mitosis.

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