91Ó°ÊÓ

Nervous tissues are made of cells specialized to receive and transmit electrical impulses from specific areas of the body and to send them to specific locations in the body.

a. cell body

The main cell of the nervous system is the neuron. The large structure with a central nucleus is the cell body of the neuron.

b. dendrite

Projections from the cell body are either dendrites specialized in receiving input or a single axon specialized in transmitting impulses.

The neuron has projections called dendrites that receive signals.

c. axon

The neuron has projections called axons that send signals.

d. glial

There are two types of glial cells: astrocytes and oligodendrocytes. Astrocytes regulate the chemical environment of the nerve cell, and oligodendrocytes insulate the axon so the electrical nerve impulse is transferred more efficiently.