Nervous tissue is the fourth major class of vertebrate tissue. The function of the nervous tissue is in communication between parts of the body. It is composed of neurons, which transmit impulses, and the neuroglia, which assist propagation of the nerve impulse as well as provide nutrients to the neuron.

All nervous tissue of an organism makes up its nervous system, which may include the brain, spinal cord, and nerves throughout the organism.

Nervous tissue is made of nerve cells that come in many varieties, all of which are distinctly characteristic by the axon or long stem like part of the cell that sends action potential signals to the next cell.

All living cells have the ability to react to stimuli. Nervous tissue is specialized to react to stimuli and to conduct impulses to various organs in the body which bring about a response to the stimulus. Nerve tissue (as in the brain, spinal cord and peripheral nerves that branch throughout the body) are all made up of specialized nerve cells called neurons. Neurons are easily stimulated and transmit impulses very rapidly. A nerve is made up of many nerve cell fibers (neurons) bound together by connective tissue. A sheath of dense connective tissue, the epineurium surrounds the nerve. This sheath penetrates the nerve to form the perineurium which surrounds bundles of nerve fibers. blood vessels of various sizes can be seen in the epineurium. The endoneurium, which consists of a thin layer of loose connective tissue, surrounds the individual nerve fibers.