massive area of the tissue dies, and is said to have undergone gangrene, or to have
(5) Infarction. Death of the tissue of an organ or portion thereof as the result
of the loss of its blood supply is known as infarction. The necrotic (dead) area itself is
called an infarct.
Hemorrhage. This is the loss of blood.
(1) Organic disorders. Injury or disease of the nervous system tissue may
result in the loss of the nerve supply to a particular part of the body. Therefore,
because of loss of enervation, secondary changes in the tissue occur, such as atrophy.
In addition, the normal functions may become paralyzed, and there may be loss of
sensation and other changes.
(2) Functional disorders. Disturbances of the mind or psyche may produce
neuroses, psychoses, or character and behavior disorders. Such disturbances may or
may not be inherited; the environment, childhood experiences, and many other factors
have a bearing on the production of psychiatric disturbances.
g. Mechanical Disturbances. Certain static mechanical abnormalities may
result in disease within the body. For example, volvulus or twisting of the intestine on
itself, torsion of the spermatic cord, strangulation of a hernia, and intussusception, are
all often on a purely mechanical basis.
h. Disorders of Metabolism, Growth, or Nutrition. Metabolism has to do with
the total chemical cycle of converting substances into forms that are usable to the body.
Metabolism occurs in two phases.
(1) Anabolism. In anabolism, foodstuffs are broke down (digested) and
reconverted into compounds which can be utilized as energy, or as building blocks for
new tissue cells and substances. In anabolism, living tissue is manufactured from
nonliving substances. This results in growth or replenishment.
(2) Catabolism. Catabolism is the breaking down of the body's complex
substances by wear, tear, and age into waste products of simpler composition for
elimination. Metabolism and growth then are dependent on the body's receiving
enough of the proper foodstuffs in order to supply its needs, in other words, on proper
nutrition. Metabolism and growth are further regulated by the vitamins and hormones.
The hormones are supplied by the ductless glands of the body (the pituitary, thyroid,
parathyroid, pancreas, adrenals, and gonads), and any disorder of these glands will
profoundly disturb growth and metabolism. The vitamins are supplied by the diet; if the
diet or nutrition is unsatisfactory, disturbances in growth and metabolism can result also.
Therefore, metabolism, growth, and nutrition are closely related to one another.