Nerve tissue consists of nerve cells called neurons and some specialized cells found only in the nervous system. The nervous system has two divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The brain and spinal cord are the organs of the CNS. They are made of neurons and specialized cells called […]

Muscle tissue is specialized for contraction. When muscle cells contract, they shorten and bring about some type of movement. There are three types of muscle tissue: skeletal, smooth, and cardiac. The movements each can produce have very different purposes.
Skeletal muscle may also be called striated muscle or voluntary muscle. Each name describes a particular aspect […]

There are several kinds of connective tissue, some of which may at first seem more different than alike. The types of connective tissue include areolar, adipose, fibrous, and elastic tissue as well as blood, bone, and cartilage. A characteristic that all connective tissues have in common is the presence of a matrix in addition to […]

Epithelial tissues are found on surfaces as either coverings (outer surfaces) or linings (inner surfaces). Because they have no capillaries of their own, epithelial tissues receive oxygen and nutrients from the blood supply of the connective tissue beneath them. Many epithelial tissues are capable of secretion and may be called glandular epithelium, or more simply, […]

Almost all the energy released by the body’s metabolism of nutrients is eventually converted into body heat. This applies even to the energy that causes muscle contraction for the following reasons: First, the maximal efficiency for conversion of nutrient energy into muscle work, even under the best of conditions, is only […]