(7) Sound. Exposure to excessive noise can cause temporary or
e. Circulatory Disturbances. Any interference with the blood flow to a portion
of the body results in a circulatory disturbance.
(1) Ischemia. A decrease in the normal diameter of an artery supplying a
portion of the body results in a decrease in the amount of blood that flows to that part.
The area becomes paler and colder than normal, and is said to be ischemic.
(2) Thrombosis. Whenever a vessel wall becomes diseased, the blood
tends to collect at the diseased or injured site and form a thrombus (clot). The presence
of an intravascular blood clot is called thrombosis.
(3) Embolism. Portions of a thrombus may break loose, and then travel
freely in the bloodstream until stopped by a vessel too small for the particle to pass
through; or foreign particles, such as air bubbles or fat globules, may be introduced into
the bloodstream and travel freely until stopped by a smaller vessel. These foreign
particles are known as emboli. The process of obstruction or occlusion of a blood vessel
by a transported foreign material is known as embolism.
(4) Gangrene. When an extremity or portion thereof loses its arterial blood
supply as the result of thrombosis, embolism, trauma, or from any other cause, a
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.
f. Neuropsychiatric Disturbances.
(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, and as a result of
the loss of innervation, secondary changes in the tissue occur, such as atrophy. Also,
the normal functions may become paralyzed and there may be loss of sensation and
(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.