Webster's New World Medical Dictionary

disorder, seasonal affective
See 
seasonal
affective disorder.
dissect
To cut apart or separate tissue, as for
anatomical study or in surgery. Also, an artery is
said to dissect when its wall is torn, as in a dissect-
ing aneurysm.
dissecting aneurysm
See 
aneurysm, dissecting.
dissociation
In psychology and psychiatry, a per-
ceived detachment of the mind from the emotional
state or even from the body. Dissociation is charac-
terized by a sense of the world as a dreamlike or
unreal place and may be accompanied by poor
memory of specific events.
dissociative disorder
A psychiatric disorder
characterized by the ability to temporarily discon-
nect from reality. Multiple personality disorder is a
discharge
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type of dissociative disorder in which, while disso-
ciating, the person believes himself or herself to be
another person.
distal
The more (or most) distant of two (or
more) things. For example, the distal end of the
thigh bone is the end of that bone that is by the
knee, most distant from the end that is near the hip.
The opposite of distal is proximal. See also
Appendix B, “Anatomic Orientation Terms.”
distal hereditary myopathy
See 
muscular dys-
trophy, distal.
diuresis
Excretion of urine, typically in large vol-
umes. See also 
diuretic.
diuretic
Something that promotes the formation
of urine by the kidney. All diuretics cause a person to
“lose water,” but they do so by diverse means,
including inhibiting the kidney’s ability to reabsorb
sodium, thus enhancing the loss of sodium and con-
sequently water in the urine (loop diuretic); enhanc-
ing the excretion of both sodium and chloride in the
urine so that water is excreted with them (thiazide
diuretic); or blocking the exchange of sodium for
potassium, resulting in excretion of sodium and
potassium but relatively little loss of potassium
(potassium-sparing diuretic). Some diuretics work
by yet other mechanisms, and some have other
effects and uses, such as in treating hypertension.
Also known as water pill. Substances in food and
drinks, such as coffee, tea, and alcoholic beverages,
may act as diuretics.
diuretic, loop
A diuretic that works by encour-
aging the loss of sodium (salt) and water by affect-
ing sodium transport at the loop area of the kidneys.
As the sodium is removed, it takes water with it.
Loop diuretics are very strong, and they should be
used only under constant medical supervision. They
can deplete the electrolyte balance, cause dehydra-
tion, reduce blood volume, and worsen certain
medical conditions. See also 
diuretic.