Obstruction of a bronchus or bronch-
iole may be caused by the accumulation
of mucus. This buildup of mucus most
commonly occurs in a baby at birth; in
abdominal or chest operation that has
pain; in certain infections such as
(whooping cough) in children or
(inflammation of the
bronchi) in adults.
Obstruction may also result from an
accidentally inhaled foreign
tumour in the lung, or enlarged
some other lung infections, or certain
exerting pressure on
the airway. The
collapsed lung may
The main symptom of atelectasis is
shortness of breath.There may also be a
cough and chest pain, depending on
the underlying cause.
DIAGNOSIS AND TREATMENT
Atelectasis can be diagnosed by
and treatment is aimed at rem-
oving the cause of the blockage. The
treatment may include
a procedure that involves
removal of the blockage using a rigid or
flexible viewing tube (see
the obstruction can be removed, the
lung should reinflate normally.
that is commonly
used to treat
caused by an impaired blood supply
to the heart muscle), and certain types
(irregular heartbeat) in
which the heart beats too rapidly.
Fatty deposits on the inner lining of an
artery that occur in
restrict blood flow. The deposits are also
known as atheromatous plaques.
other fatty substances (lipids) in the
walls of arteries, causing the arteries to
narrow. Atherosclerosis can affect arter-
ies in any area of the body and is a
major cause of
heart attack (see
), and poor circu-
lation in the legs.
The arteries become narrowed when
fatty substances carried in the blood
accumulate on the inside lining of the
known as atheromatous plaques. These
deposits restrict the blood flow through
the arteries. In addition, the muscle
layer of the artery wall becomes thick-
ened, which narrows the artery even
further. Platelets (tiny blood cells that
may collect in clumps on the surface of
the deposits and initiate the formation
of blood clots. A large clot may com-
pletely block the artery, resulting in the
organ it supplies being deprived of
oxygen. A complete blockage in a coro-
nary artery can cause a sudden, often
fatal, heart attack.
The risk of developing atherosclerosis is
determined largely by the level of cho-
depends on dietary and genetic factors.
Atherosclerosis is more common in
developed countries, where most people
eat a diet high in fat. Some disorders
can be asso-
ciated with a high cholesterol level,
regardless of diet.
symptoms in its early stages. As the con-
dition progresses, symptoms occur as a
result of reduced, or total absence of,
blood supply to the organs supplied by
the affected arteries.
Partial blockage of the coronary art-
eries (which supply the heart muscle)
may produce symptoms such as the
chest pain of
of the arteries supplying blood to the
(symptoms and signs of a
that last for less than 24 hours) and
episodes of dizziness.
ARTERIAL DEGENERATION IN ATHEROSCLEROSIS
Atherosclerosis is narrowing of the arteries due to plaques of atheroma on their inner
linings. The plaques are composed mainly of fats, deposited from the bloodstream,
that disrupt normal blood flow through the artery. Men are affected earlier than women
because premenopausal women are protected by natural oestrogen hormones.
Micrograph of artery in atherosclerosis
The artery shown here has an atheromatous
(fibrous and fatty) plaque deposit on its inner
wall. The lumen (channel) has been narrowed,
disrupting blood flow.
A deposit of atheromatous plaque disrupts
normal blood flow through the artery at the
pointwhere it branches. This occurs because
ofthe greater level ofturbulence in this area.