ATENOLOL
CAUSES
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
people
with
asthma;
following
an
abdominal or chest operation that has
made
coughing
difficult because
of
pain; in certain infections such as
per-
tussis
(whooping cough) in children or
chronic
bronchitis
(inflammation of the
bronchi) in adults.
Obstruction may also result from an
accidentally inhaled foreign
body, a
tumour in the lung, or enlarged
lymph
nodes
(which
occur
in
tuberculosis,
some other lung infections, or certain
forms of
cancer)
exerting pressure on
the airway. The
collapsed lung may
become infected.
SYMPTOMS
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
chest
X-ray,
and treatment is aimed at rem-
oving the cause of the blockage. The
treatment may include
physiotherapy
or
bronchoscopy,
a procedure that involves
removal of the blockage using a rigid or
flexible viewing tube (see
endoscope).
If
the obstruction can be removed, the
lung should reinflate normally.
atenolol
A
beta-blocker drug
that is commonly
used to treat
hypertension
(high blood
pressure),
angina pectoris
(chest pain
caused by an impaired blood supply
to the heart muscle), and certain types
of
arrhythmia
(irregular heartbeat) in
which the heart beats too rapidly.
atheroma
Fatty deposits on the inner lining of an
artery that occur in
atherosclerosis
and
restrict blood flow. The deposits are also
known as atheromatous plaques.
atherosclerosis
The accumulation
of
cholesterol
and
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
stroke,
heart attack (see
myocardial infarction
), 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
arteries
and
form
yellow
deposits
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
are
responsible
for
blood
clotting)
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.
CAUSES
The risk of developing atherosclerosis is
determined largely by the level of cho-
lesterol
in
the
bloodstream,
which
depends on dietary and genetic factors.
Atherosclerosis is more common in
developed countries, where most people
eat a diet high in fat. Some disorders
such as
diabetes mellitus
can be asso-
ciated with a high cholesterol level,
regardless of diet.
SYMPTOMS
Atherosclerosis
usually
produces
no
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
angina pectoris
. Narrowing
of the arteries supplying blood to the
brain
may
cause
transient ischaemic
attacks
(symptoms and signs of a
stroke
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.
Direction of
blood flow
RISKFACTORS
Cigarette smoking
Hypertension
Male gender
Obesity
Physical inactivity
Diabetes mellitus
Heredity
High cholesterol
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.
Normal artery
Atheromatous
plaque
Lumen
Artery
wall
muscle
Atheromatous
plaque
Atherosclerotic artery
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.
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