Kathy Baird, age 14, of Casper, Wyo., for her question:

WHAT DOES A PATHOLOGIST DO?

Pathology is the study of disease, or any condition that limits power, length or enjoyment of life. The pathologist uses modern instruments and methods, such as electron microscopy, to help him recognize the changes caused by disease in the tissues and organs of the body. He tries to explain why a diseased body acts differently from a normal body .

The pathologist uses his knowledge of diseased tissues and body fluids to aid the physician.

Pathological tests help doctors diagnose a disease and the extent of its attack. These tests may include examinations of the blood, urine and tissues. The use of laboratory tests to diagnose disease is called clinical pathology.

The pathologist also studies diseased parts removed by surgery. He may examine corpses to learn the exact cause of death. This examination is called an autopsy or post mortem examination.

Special kinds of pathology study diseases of separate organ systems. For example, neuropathology concerns diseases of the nerves.