diaphragm (redirected from Potter-Bucky diaphragm)

diaphragm (dī`əfrăm'), term used to describe any of several large muscles, found in humans and other mammals, which separate two adjacent regions of the body. The most commonly known muscle of this class is the thoraco-abdominal diaphragm. In humans, the thoraco-abdominal diaphragm acts as a partition between the cavity of the chest and that of the abdomen. The chief muscle used in respiration, it is relaxed and dome-shaped during exhalation. During inhalation it contracts, pulling downward, and with the combined contraction of the chest muscles allows the chest cavity to expand. Any interference with its free movement, as in the paralysis of poliomyelitis, seriously impedes the function of the lungs and therefore endangers life. In its downward movement the thoraco-abdominal diaphragm also stimulates the stomach and liver and thus aids in the digestive processes. Spasmodic contraction results in hiccups. The thoraco-abdominal diaphragm is also subject to developmental defects, hernia, injury, displacement, and infection. Other diaphragms in the human body include the pelvic diaphragm and the urogenital diaphragm, which use similar muscular contractions and expansions in their respective functions.

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diaphragm

Dome-shaped muscular and membranous structure between the thoracic and abdominal cavities. The principal muscle used in respiration, it is also important in coughing, vomiting, excretion, and other expulsive functions. Spasms of the diaphragm produce hiccups. The aorta passes behind the diaphragm; the inferior vena cava and esophagus pass through it. Protrusion of part of the stomach above the diaphragm is called a hiatal hernia.

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diaphragm

1. Anatomy any separating membrane, esp the dome-shaped muscular partition that separates the abdominal and thoracic cavities in mammals

2. Optics a disc with a fixed or adjustable aperture to control the amount of light or other radiation entering an optical instrument, such as a camera

3. Chem

a. a porous plate or cylinder dividing an electrolytic cell, used to permit the passage of ions and prevent the mixing of products formed at the electrodes

b. a semipermeable membrane used to separate two solutions in osmosis

4. Botany a transverse plate of cells that occurs in the stems of certain aquatic plants