Nerve Tissue consists of the tissues of the brain, spinal cord, associated peripheral nerves, and specialized sensory organs. Neurons are the main cellular component and come in three types. They are the “sensing,” “thinking” and “connecting,” and action directing cells of the nervous system. Sensory Neuron Interneuron Motor Neuron
Along with the neurons, nerve tissue contains specialized connective tissue cells called the neuroglia (neuroglial or glial cells) . These cells actually outnumber neurons about 10 to 1 and they function to support and nourish the individual neurons.
Nerve tissue (neurons supported by neuroglia) is functionally specialized in two ways: 1. Irritability – the responsiveness to stimuli. These stimuli are such things as: a. heat f. touch b. cold g. injury ("pain") c. pressure h. electrical d. light i. taste e. sound j. smell 2. Conductivity - the ability to carry an impulse. Signals collected in the extremities must be carried all the way to the brain for processing and all the way back to some location for action.
Nerve tissue appears visually in two different ways. Some nerve tissue has a characteristic gray coloring while other nerve tissue is a shiny, glossy white color.
1. Gray Matter - This is found in the outer layer of the cortex and other parts of the brain, the core of the spinal cord, and in the peripheral nerves. Gray matter consists mainly of neuron bodies.
2. White Matter -This is found in the brain, spinal cord, and nerves, and consist largely of the myelinated axons of neurons.