Transcript CV disorders - Wilson`s Web Page

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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Circulatory System Disorders
Circulatory system disorders are also known as
cardiovascular disease (CVD). CVD is the leading
cause of death in most Western countries
Examples of CVD include:
• Atherosclerosis
• Hypertension
• Heart Valve Disease
• Stroke, Heart Attack, and Aneurysm
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Atherosclerosis
Figure 10B Coronary arteries and plaque. Atherosclerotic plaque is an irregular
accumulation of cholesterol and fat. When plaque is present in a coronary artery, a heart
attack is more likely to occur because of restricted blood flow.
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Atherosclerosis
• accumulation of soft masses of fatty materials (e.g.,
cholesterol) beneath the inner linings of arteries.
• Deposits of these materials are called plaque
• Plaque narrows arteries by protruding into the blood
vessel; this results in restricted blood flow
• Plaque can also cause platelets to adhere to the arterial
wall, forming a clot
o If the clot remains stationary, it is called a thrombus
o If the clot dislodges, it is called an embolus
o Thromboembolism is a clot that has been carried in the
blood and has become lodged in a blood vessel
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Hypertension
Hypertension is high blood pressure.
• Under the age of 45 years, blood pressure above 130/90 mm
Hg is considered abnormally high
• Called “the silent killer” because it may not be detected until a
stroke or heart attack occurs
• Occurs secondary to a narrowing of arteries due to
atherosclerosis
o Narrowed arteries cause an increase in blood pressure,
since more force is needed to move blood through the
blood vessels
• Treatment involves vasodilators (which dilate blood vessels)
and diuretics (which decrease blood volume by increasing
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urine)
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Heart Valve Disease
Heart valve disorders result in the backflow of blood, and
range from mild to severe.
• Heart valves can be malformed at birth, or they can
degenerate due to age or infections
• Result from narrowing (stenosis) of the aortic valve
opening, or from mitral valve prolapse (abnormally
thickened leaflets of the mitral valve protrude into the left
ventricle)
• Treatment involves repair of faulty valves in open-heart
surgery or replacement with artificial valves or valves from
an animal or deceased human
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Stroke, Heart Attack, Aneurysm
Stroke
• Occurs when an arteriole in the brain bursts or is blocked
by an embolus (a clot that has been dislodged)
• Results in lack of oxygen (due to impaired blood flow) to
the brain, causing a portion of the brain to die
• Paralysis or death can result
• Symptoms of stroke include numbness in the hands or face,
difficulty speaking, or temporary blindness
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Heart Attack
• When a coronary artery becomes partially blocked, angina
pectoris occurs, resulting in a squeezing or burning
sensation in the chest
• When a coronary artery is completely blocked, a portion of
the heart muscle dies due to lack of oxygen, and a heart
attack (myocardial infarction) occurs
• Treatment includes vasodilators (nitroglycerin) to dilate
blood vessels
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Aneurysm
• Occurs when there is a ballooning of a blood vessel, most
often the abdominal aorta or the arteries leading to the
brain
• Atherosclerosis and hypertension can weaken the wall of
the artery to the point that an aneurysm develops
• If the aorta bursts, about 50% of victims die before
reaching the hospital
• Treatment involves replacing the damaged or diseased
portion of the vessel with a synthetic graft
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Treatment for Cardiovascular Disorders
Coronary Bypass Operations
• Involves grafting arteries to
bypass an obstructed coronary
artery
• A segment from another blood
vessel in the body is stitched to
one end of the aorta; the other
end is stitched to a coronary
artery past the point of
obstruction
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Figure 10.26 Bypassing blocked coronary arteries. This is a 3-D scan of the heart of
a patient who received a triple bypass operation. The surgeon has bypassed two blocked
arteries using vessels removed from another part of the body and used an existing artery
that branches off the left subclavian artery to bypass a third blocked artery.
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Stem Cells
• Stem cells may be used to regenerate heart muscle that
has been damaged by a heart attack
• Stem cells injected directly into the damaged heart muscle
of mice and rats differentiated into new heart muscle cells
and new blood vessels
• A “bioartificial” human heart has been grown by a
research group by using cardiac muscle cells from a
cadaver as a “scaffold” for human stem cells
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Clearing Clogged Arteries
• Angioplasty involves inserting a
catheter into a clogged artery.
o When the catheter reaches
the site of the clogged
artery, a balloon is inflated
to force the vessel open
• A stent is a metal mesh tube
that inflates, expands, and locks
the balloon into place.
o Some stents are coated with
medications that inhibit
inflammation and scar
formation
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Figure 10.27 Angioplasty with stent
placement. a. A plastic tube (catheter) is
inserted into the coronary artery until it
reaches the clogged area. b. A metal stent
with a balloon inside it is pushed out the end
of the plastic tube into the clogged area.
c. When the balloon is inflated, the vessel
opens, and the stent is left in place to keep
the vessel open.
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Dissolving Blood Clots
• Thromboembolisms can be treated with tissue
plasminogen activator (tPA)
o Converts plasminogen to plasmin, an enzyme that
dissolves blood clots
• Aspirin can be prescribed for individuals with symptoms
of angina or stroke
o Reduces stickiness of platelets and lowers the
probability of clot formation
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Heart Transplants and Artificial Hearts
Heart transplants
• The need for hearts to transplant
is greater than the supply
• A left ventricular assist device
(LVAD) can be implanted in the
abdomen of patients waiting for
an implant
o A tube passes blood from
the left ventricle to the
LVAD, which pumps it into
the aorta
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Figure 10.28 Human Heart. This human
heart being cradled in the hands of a
surgeon is about to be transplanted into
a person whose own heart no longer
functions properly.
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Chapter 10: Circulatory System and Lymphatic System
Section 10.8
Heart Transplants and Artificial Hearts
Artificial hearts
• A total artificial heart (e.g., AbioCor)
contains:
o An internal battery
o A controller (regulates pumping speed)
o An external battery (powers the device
by passing electricity through the skin)
• A pump moves silicon hydraulic fluid
between the left and right sacs to force
blood out of the heart and into the
pulmonary trunk and aorta
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Figure 10.29 A total
artificial heart. The
AbioCor replacement
heart is designed to be
implanted within the
chest cavity.