Anatomy and Related Anatomical Terms

The part of the body below the thorax, containing the digestive organs and female reproductive organs: The abdomen is separated from the thorax by the diaphragm, a sheet of muscular tissue, while the "thorax" is the part of the human body between the neck and abdomen, enclosed by the ribs and containing the heart and lungs.

The ability of the eye to focus on near or far objects by the changing of the shape of the lens: The automatic adjustment of the organ of vision, or the accommodation, effects the focus on different distances, which is caused by the change in the convexity of the crystallline lens.

A chemical that serves as a neurotransmitter, communicating nerve impulses between the cells of the nervous system.

Acetylcholine, or ACh, is largely associated with the transmission of impulses across the synapse (junction) between the nerve and muscle cells, causing the muscles to contract.

The change in the potential difference (voltage) across the membrane of a nerve cell when an impulse passes along it:

An action potential is a variation in potential (from about -60 to +45 millivolts) that accompanies the passage of sodium and potassium ions across the membrane.

In cells, the use of energy to move substances, usually molecules or ions, across a membrane: Active transport requires the application of energy in metabolism and is supported by pumps, or also known as carrier proteins.

A mass of lymphoid tissue, similar to tonsils, located in the upper part of the throat, behind the nose: The adenoids are part of a child's natural defenses against the entry of germs, but they usually shrink and disappear by the age of ten.

A connective tissue having an abundance of fat-storing cells and blood vessels for transporting fats: The adipose tissue is a connective tissue that serves as an energy reserve and also pads some organs.

Adipose tissue is normally called "fat tissue" and consists of large spherical cells filled with fat. Major layers are in the inner layer of the skin and around the kidneys and heart.

A triangular gland situated on top of the kidney; suprarenal gland: The cortex of the adrenal gland (outer part) secretes various steroid hormones and other hormones that control salt and water metabolism and regulate the use of carbohydrates, proteins, and fats.

The medulla, the inner part of the adrenal gland, secretes the hormones adrenaline and noradrenaline which, during times of stress, prepare the body for "fight or flight".

The hormone that is secreted by the medulla of the adrenal glands; epinephrine: Adrenaline is synthesized from a closely related substance, noradrenaline, and the two hormones are released into the bloodstream in situations of fear or stress.

A hormone secreted by the anterior lobe of the pituitary gland: The adrenocorticotrophic hormone encourages the growth of the adrenal gland and is applied as a medical treatment for rheumatoid arthritis, skin ailments and other disorders.

A tube adapted for digestion, through which food passes: The alimentary canal is a complex organ consisting of the mouth cavity, pharynx, esophagus, stomach, and the small and large intestines.

One of the many thousands of tiny air sacs in the lungs: The alveoli are important for the exchange of oxygen and carbon dioxide and this process takes place between air and the bloodstream.

One of a group of enzymes that break down starches into their component molecules (sugars) for use in the body: Amylase is found in saliva, as ptyalin, and in pancreatic juices.

The estimated age of an individual based on the person's structure: Anatomic age is the physical age of a human being and relates to the development or deterioration of the body as compared to that of other people of the same chronological age.

The study of the effects of disease on the structures of the body: The medical discipline of anatomic pathology is concerned with the identification of a disease based on microscopic, macroscopic, biochemical, immunologic and molecular research and the investigation of organs and tissues.