2. ORGANS

An organ is the part of the human body that serves as an instrument for the adaptation of the organism to the environment. An organ is a part of a single whole and cannot exist outside the organism.

At the same time, an organ is a relatively integral structure which has a definite, inherent only in it, form, structure, function, development, and position in the organism. The heart, for instance, is made up not only of cardiac muscular tissue but of different types of connective tissue (fibrous, elastic), elements of the nervous system (cardiac nerves), endothelium, and unstrained muscle fibres (vessels).

Permanent (definite) organs, i.e. those characteristic of an adult organism and resisting throughout life and temporary (provisional) organs, which appear in a certain stage of the organism?s development and then disappear are distinguished from the standpoint of the periods of ontogenesis.

The human body is made up of the head, neck, trunk, and two parts of limbs, or extremities, the upper and the lower. The following parts are distinguished in the head: the forehead, the highest point of the skull, the back of the head, the temples, and the face. The trunk consists of the chest, the abdomen, and the back.

All organs of the human body are included in systems, which work together. The organism of the human body consists of such important systems as:

Locomotor system - provides motion and supports the body in necessary position. It consists of the skeleton, muscles, ligaments and joints.

Digestive system - controls the digestive process, provides a person with energy.

Pulmonary system - consists of the lungs and pulmonary ways to process oxygen and carbon dioxide, saturating blood with oxygen.