Disturbances of the body's acid-base
balance result in either
sive blood acidity) or
acidosis A disturbance of the body's
in which there is an
accumulation of acid or loss of
(base). There are 2 types of acidosis:
metabolic and respiratory.
One form of metabolic acidosis is
ketoacidosis, which occurs in uncon-
Metabolic acidosis may also be caused
by loss of bicarbonate (an alkali) as a
result of severe diarrhoea. In
there is insufficient excretion of
acid in the urine.
Respiratory acidosis occurs if breathing
fails to remove enough carbon dioxide
from the lungs. The excess carbon di-
where it dissolves to form carbonic acid.
Impaired breathing leading to respira-
tory acidosis may be due to chronic
obstructive pulmonary disease (see
monary disease, chronic obstructive),
acid reflu x Regurgitation of acidic fluid
from the stomach into the
due to inefficiency of the muscular valve
at the lower end of the oesophagus.
reflux disease (GORD), acid reflux may
inflame the oesophagus, resulting in
occur in pregnancy and often affects
acne A chronic skin disorder caused by
inflammation of the hair follicles and
sebaceous glands in the skin. The most
common type is acne vulgaris, which
almost always develops during puberty.
Acne spots are caused by the obstruc-
tion of hair follicles by sebum (the oily
substance secreted by the sebaceous
glands). Bacteria multiply in the follicle,
causing inflammation. The change in
sebum secretion at puberty seems to be
linked with increased levels of
(male sex hormones).
Acne may be brought on or aggravated
by drugs such as
Exposure to certain chemi-
cals and oils in the workplace can also
cause a type of acne.
Acne develops in areas of skin with a
high concentration of sebaceous glands,
mainly the face, centre of the chest,
upper back, shoulders, and around the
neck. Milia (whiteheads), comedones
ules (firm swel-
lings beneath the
skin), and cysts
swellings) are the
cysts, leave scars
after they heal.
There is no inst-
ant cure for acne,
but washing the
affected areas at
least twice daily
may help to keep
it under control.
Topical drug treat-
ments, such as benzoyl peroxide or
retinoic acid, unblock the pores and
promote healing. Ultraviolet light can
be beneficial. If topical treatment has
failed, oral drug treatment with
, hormones, or
given. Acne improves slowly over time,
often clearing up by the end of the
acoustic nerve The part of the
that is concerned with hearing. It is also
known as the auditory nerve.
acoustic neurom a A rare, noncancer-
ous tumour arising from supporting
cells that surround the 8th cranial nerve
), usually within the
internal auditory meatus (the canal in
the skull through which the nerve pass-
es from the inner ear to the brain).
Usually, the cause of an acoustic neuro-
ma is unknown. However, tumours that
affect the nerves on both sides of the
head simultaneously may be part of a
condition known as
Acoustic neuroma can cause
, loss of balance, and pain in the
face and the affected ear.
Diagnosis is made by
X-rays, CT scanning,
Surgery may be needed, but treatment