Webster's New World Medical Dictionary

excisional biopsy
See 
biopsy, excisional.
exclamation point hair
A short, broken-off hair
that is found in an area of hair loss and is narrower
closer to the scalp than at the other end (and there-
fore looks like an exclamation point). Exclamation
point hair is a key diagnostic finding in a disorder
called alopecia areata. See also 
alopecia areata.
excrescence
An abnormal outgrowth as, for
example, a wart.
exercise, aerobic
See 
aerobic exercise.
exercise treadmill
A machine used to obtain a
continuous electrocardiogram recording of the
heart as a patient performs increasing levels of exer-
cise. An exercise treadmill permits the detection of
abnormal heart rhythms (arrhythmias) and pro-
vides a screening test for the presence of narrowed
arteries to the heart (coronary arteries). Narrowing
of these arteries can limit the supply of oxygenated
blood to the heart muscle during exercise.
exercise-induced asthma
See 
asthma, exer-
cise-induced.
exercise-induced bronchospasm
See 
asthma,
exercise-induced.
euthanasia
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exfoliate 1
To peel off scaly skin spontaneously.
For example, the skin exfoliates from the palms and
soles in psoriasis, Kawasaki disease, and Reiter syn-
drome.
2
To deliberately wear away the top layer
of skin, as may be done gently by a facial technolo-
gist who is applying a topical skin treatment for cos-
metic purposes or more severely by a dermatologist
treating acne. In the latter case, the most common
exfoliating methods are sanding and chemical peels.
exocrine
Pertaining to the secretion of a sub-
stance out of the body through a duct. The exocrine
glands include the salivary glands, sweat glands, and
glands within the gastrointestinal tract. Exocrine is
as opposed to endocrine, which refers to the secre-
tion of a substance (a hormone) within the body
through the bloodstream. See also 
endocrine.
exogenous
Originating from outside an organ-
ism. For example, insulin taken by a diabetic is
exogenous insulin. See also 
endogenous.
exon
A region of DNA in a gene that is transcribed
(read) into mature messenger RNA. An exon is the
protein-coding part of a gene. See also 
intron.