Webster's New World Medical Dictionary

autoimmune thyroiditis
See 
Hashimoto dis-
ease.
autoimmunity
The state of being attacked by
one’s own immune system. Patients whose misdi-
rected immune systems attack their own body tis-
sues are said to have autoimmunity. See also
antinuclear antibody; autoimmune disorder.
autologous
In blood transfusion and transplan-
tation, a situation in which the donor and recipient
are the same person. Patients scheduled for non-
emergency surgery may be autologous donors by
donating blood for themselves that will be stored
until the surgery. An autologous graft is a graft (such
as a graft of skin) that is provided for oneself.
automated external defibrillator
A device that
automatically analyzes the heart rhythm and that—
if it detects a problem that may respond to an elec-
trical shock—delivers a shock to restore a normal
heart rhythm. Thanks to their small size and ease of
use, AEDs have been installed in many settings
(such as schools and airports), and serve a role in
expanding the number of opportunities for life-sav-
ing defibrillation. Abbreviated AED.
automatism
A behavior that is performed with-
out conscious knowledge and that does not appear
to be under conscious control. This curious type of
behavior occurs in a number of neurological and
psychiatric disorders. The neurologic disorders
associated with automatism include narcolepsy and
some forms of epilepsy. The psychiatric conditions
associated with automatism include schizophrenia
and fugue states. Automatism involves doing some-
thing “automatically” and not remembering after-
ward how one did it or even that one did it. Also
known as automatic behavior. See also 
epilepsy;
seizure disorders.
autonomic nervous system
A part of the nerv-
ous system that regulates key involuntary functions
of the body, including the activity of the heart mus-
cle; the smooth muscles, including the muscles of
the intestinal tract; and the glands. The autonomic
nervous system has two divisions: the sympathetic
nervous system, which accelerates the heart rate,
constricts blood vessels, and raises blood pressure,
and the parasympathetic nervous system, which
slows the heart rate, increases intestinal and gland
activity, and relaxes sphincter muscles.