GLOMERULOSCLEROSIS
G
glomerulosclerosis
Scarring
caused
by
damage
to
the
glomeruli (see
glomerulus
) ,
the filtering
units of the kidney.
M ild glomerulosclerosis occurs as a
normal part of the aging process. The
condition may also occur in some severe
types of
glomerulonephritis
.
In addition, it
may be associated with
diabetes mellitus,
hypertension
(high blood pressure),
AIDS
,
or intravenous
drug abuse
.
glomerulus
A filtering
unit
in
the
kidney
.
Each
glomerulus consists of a cluster of capil-
laries (tiny blood vessels) enclosed in a
capsule and supplied with blood from
the renal artery; it forms part of a larger
filtering unit called a
nephron
.
Filtered
blood eventually leaves the kidney via the
renal vein. (See also
glomerulonephritis;
glomerulosclerosis
.)
glomus tumour
A small, bluish swelling in the skin,
usually on a finger or toe near or under
the nail. The swelling feels tender and is
more painful if the lim b is hot or cold.
Glomus tumours are caused by an over-
growth
of the nerve
structures that
normally control blood flow and tem-
perature in the skin. They are harmless
but can be surgically removed.
glossectomy
Removal of all or part of the
tongue
.
Glossectomy may be performed to treat
tongue cancer
.
If a large part of the
tongue is removed, speech is impaired
and eating is difficult.
glossitis
Inflammation
of the
tongue
.
The tongue
feels sore and swollen and looks red and
smooth; adjacent parts of the mouth
may also be inflamed.
Glossitis occurs in various forms of
anaemia
and
in
vitamin B
deficiency.
Other causes include infection of the
mouth (especially by
herpes simplex
) ,
irritation by dentures, and excessive use
of alcohol, tobacco, or spices.
Treatment is for the underlying cause.
Rinsing of the mouth with a salt solu-
tion and good
oral hygiene
may help to
relieve the soreness.
glossodynia
A painful, burning sensation in the
tongue
,
often with no known cause.
Glossodynia tends to disappear of its
own accord over time.
glossolalia
Speaking in an imaginary language that
has no actual meaning or syntax. (See
also
neologism
.)
glossopharyngeal nerve
The ninth
cranial nerve
.
This nerve sup-
plies the tongue and the throat, and
performs both sensory and motor func-
tions. It conveys sensations, especially
taste, from the back of the
tongue
,
regu-
lates
the secretion
of saliva
by
the
parotid gland
,
and controls movement of
the throat muscles.
glottis
The part of the
larynx
(voice-box) that
consists of the
vocal cords
and the slit-
like opening between them.
glucagon
A
hormone
that stimulates the break-
down of stored
glycogen
into
glucose
(a
simple sugar). Glucagon is released by
the
pancreas
when the blood level of
glucose is low (see
feedback
).
Glucagon is used as an injected drug
in the emergency treatment of people
with
diabetes mellitus
w ho are uncon-
scious as a result of
hypoglycaemia
(low
blood glucose). Nausea and vomiting
are occasional adverse effects.
glucagonoma
A tumour of the
pancreas
that secretes
glucagon
(the hormone responsible for
raising blood sugar levels). Glucagon-
omas,
w hich
can
be
cancerous
or
noncancerous, may lead to attacks of
hyperglycaemia
(high
blood
glucose)
due to excess glucagon production.
glucocorticoids
A group of
corticosteroid hormones
,
pro-
duced by the cortex (outer layer) of the
adrenal glands
,
that affect the chemical
breakdown of
carbohydrates
by increas-
ing both the blood sugar level and the
amount of
glycogen
stored in the liver.
Glucocorticoids also enable the body to
respond effectively to physical stress.
Both natural and synthetic glucocorti-
coids are used to treat inflammatory
conditions (see
corticosteroid drugs
) .
The
main glucocorticoid is
hydrocortisone
,
also called cortisol.
gluconeogenesis
A process in w hich
glucose
(a simple
sugar)
is
synthesized
from
sources
other than
carbohydrates,
such as
amino
acids
and
glycerol
.
The process, w hich
occurs mainly in the
liver
and muscles,
is an important source of energy when
insufficient amounts
of carbohydrate
are
available
(for
example,
between
meals or when a person is fasting).
glucosamine
A molecule that occurs naturally as a
component of various substances in the
body, including
cartilage
and
collagen
.
Glucosamine is also sold as a food sup-
plement and is recommended to relieve
symptoms of
arthritis
.
glucose
A simple
sugar
(monosaccharide) that
is naturally present in fruits and is also a
product of the digestion of
starch
and
sucrose
.
Glucose is the chief source of
energy for the body and is carried to all
tissues in the circulation. (The term
“blood sugar” refers to levels of glucose
in the bloodstream.)
The level of glucose in the blood is
normally kept fairly constant by the
actions
of various
hormones
,
notably
insulin
,
glucagon
,
adrenaline
,
corticosteroid
hormones
,
and
growth hormone
.
An ab-
normally high level of glucose in the
blood (know n as
hyperglycaemia
) may
cause glucose to be lost into the urine.
An abnormally low blood glucose level
is called
hypoglycaemia
.
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