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Transcript
4th Years
University of Babylon
Anesthesia
College of Nursing
Lec.4
Dr. Naji Yassesr Al-Mayyahi
_______________________________________________________________
I. Cardiovascular System
The cardiovascular system consists of the heart, blood vessels, and the
approximately 5 liters of blood that the blood vessels transport. Responsible for
transporting oxygen, nutrients, hormones, and cellular waste products
throughout the body, the cardiovascular system is powered by the body’s
hardest-working organ — the heart, which is only about the size of a closed fist.
Even at rest, the average heart easily pumps over 5 liters of blood throughout
the body every minute...
The Heart
The heart is a muscular pumping organ located medial to the lungs along the
body’s midline in the thoracic region. The bottom tip of the heart, known as its
apex, is turned to the left, so that about 2/3 of the heart is located on the body’s
left side with the other 1/3 on right. The top of the heart, known as the heart’s
base, connects to the great blood vessels of the body:
1.the aorta,
2.vena cava,
3.pulmonary trunk,
4.and pulmonary veins.
Circulatory Loops
There are 2 primary circulatory loops in the human body: the pulmonary
circulation loop and the systemic circulation loop.
1.Pulmonary circulation transports deoxygenated blood from the right side of
the heart to the lungs, where the blood picks up oxygen and returns to the left
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side of the heart. The pumping chambers of the heart that support the
pulmonary circulation loop are the right atrium and right ventricle
2.Systemic circulation carries highly oxygenated blood from the left side of the
heart to all of the tissues of the body (with the exception of the heart and lungs).
Systemic circulation removes wastes from body tissues and returns
deoxygenated blood to the right side of the heart. The left atrium and left
ventricle of the heart are the pumping chambers for the systemic circulation
loop.
Blood Vessels
Blood vessels are the body’s highways that allow blood to flow quickly and
efficiently from the heart to every region of the body and back again. The size
of blood vessels corresponds with the amount of blood that passes through the
vessel. All blood vessels contain a hollow area called the lumen through which
blood is able to flow. Around the lumen is the wall of the vessel, which may be
thin in the case of capillaries or very thick in the case of arteries.
There are three major types of blood vessels: arteries, capillaries and
veins. Blood vessels are often named after either the region of the body through
which they carry blood or for nearby structures.
Arteries and Arterioles: Arteries are blood vessels that carry blood away from
the heart. Blood carried by arteries is usually highly oxygenated, having just left
the lungs on its way to the body’s tissues. The pulmonary trunk and arteries of
the pulmonary circulation loop provide an exception to this rule – these arteries
carry deoxygenated blood from the heart to the lungs to be oxygenated.
Smaller arteries are more muscular in the structure of their walls. The
smooth muscles of the arterial walls of these smaller arteries contract or expand
to regulate the flow of blood through their lumen. In this way, the body controls
how much blood flows to different parts of the body under varying
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circumstances. The regulation of blood flow also affects blood pressure, as
smaller arteries give blood less area to flow through and therefore increases the
pressure of the blood on arterial walls.
Arterioles are narrower arteries that branch off from the ends of arteries
and carry blood to capillaries. They face much lower blood pressures than
arteries due to their greater number, decreased blood volume, and distance from
the direct pressure of the heart. Thus arteriole walls are much thinner than those
of arteries. Arterioles, like arteries, are able to use smooth muscle to control
their aperture and regulate blood flow and blood pressure.
Capillaries: Capillaries are the smallest and thinnest of the blood vessels in
the body and also the most common. They can be found running throughout
almost every tissue of the body and border the edges of the body’s avascular
.tissues. Capillaries connect to arterioles on one end and venules on the other
Precapillary sphincters are bands of smooth muscle found at the arteriole
ends of capillaries. These sphincters regulate blood flow into the capillaries.
Since there is a limited supply of blood, and not all tissues have the same
energy and oxygen requirements, the precapillary sphincters reduce blood flow
to inactive tissues and allow free flow into active tissues.
Veins and Venules: Veins are the large return vessels of the body and act as
the blood return counterparts of arteries. Because the arteries, arterioles, and
capillaries absorb most of the force of the heart’s contractions, veins and
venules are subjected to very low blood pressures. This lack of pressure allows
the walls of veins to be much thinner, less elastic, and less muscular than the
walls of arteries.
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Cardiovascular disease
Heart and blood vessel disease — also called heart disease — includes
numerous problems, many of which are related to a process called
atherosclerosis. Atherosclerosis is a condition that develops when a substance
called plaque builds up in the walls of the arteries. This buildup narrows the
arteries, making it harder for blood to flow through. If a blood clot forms, it can
stop the blood flow. This can cause a heart attack or stroke
Coronary artery disease (CAD), also known as ischemic heart disease
is a group of diseases that includes: 0(IHD
stable angina, unstable angina, myocardial infarction, and sudden cardiac
It is within the group of cardiovascular diseases of which it is the most .death
A common symptom is chest pain or discomfort which may .common type
travel into the shoulder, arm, back, neck, or jaw. Occasionally it may feel like
heartburn. Usually symptoms occur with exercise or emotional stress, last less
than a few minutes, and get better with rest. Shortness of breath may also occur
and sometimes no symptoms are present. The first sign is occasionally a heart
.attack. Other complications include heart failure or an irregular heartbeat
heart attack
A heart attack occurs when the blood flow to a part of the heart is
blocked by a blood clot. If this clot cuts off the blood flow completely, the part
of the heart muscle supplied by that artery begins to die. Most people survive
their first heart attack and return to their normal lives to enjoy many more years
of productive activity. But having a heart attack does mean you have to make
some changes. The doctor will advise you of medications and lifestyle changes
according to how badly the heart was damaged and what degree of heart disease
caused the heart attack. Limitation of blood flow to the heart causes ischemia
(cell starvation secondary to a lack of oxygen) of the myocardial cells.
Myocardial cells may die from lack of oxygen and this is called a myocardial
infarction (commonly called a heart attack). It leads to heart muscle damage,
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heart muscle death and later myocardial scarring without heart muscle
regrowth. Chronic high-grade stenosis of the coronary arteries can induce
transient ischemia which leads to the induction of a ventricular arrhythmia,
which may terminate into ventricular fibrillation leading to death
Other Types of Cardiovascular Disease
Heart failure: This doesn't mean that the heart stops beating. Heart failure,
sometimes called congestive heart failure, means the heart isn't pumping blood
as well as it should. The heart keeps working, but the body's need for blood and
oxygen isn't being met. Heart failure can get worse if it's not treated. If your
loved one has heart failure, it's very important to follow the doctor's orders.
.Learn more about heart failure
Arrhythmia: This is an abnormal rhythm of the heart. There are various types
of arrhythmias. The heart can beat too slow, too fast or irregularly. Brady cardia
is when the heart rate is less than 60 beats per minute. Tachycardia is when the
heart rate is more than 100 beats per minute. An arrhythmia can affect how well
the heart works. The heart may not be able to pump enough blood to meet the
body's needs. Learn more about arrhythmia
Heart valve problems: When heart valves don't open enough to allow the
blood to flow through as it should, it's called stenosis. When the heart valves
don't close properly and allow blood to leak through, it's called regurgitation.
When the valve leaflets bulge or prolapse back into the upper chamber, it’s a
condition called mitral valve prolapse. When this happens, they may not close
properly. This allows blood to flow backward through them. Discover more
about the roles your heart valves play in healthy circulation.
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Cardiac arrest:
Cardiac arrest is a sudden stop in effective blood flow due to the failure of
the heart to contract effectively. Symptoms include loss of consciousness and
abnormal or absent breathing. Some people may have chest pain, shortness of
breath, or nausea before this occurs. If not treated within minutes, death usually
occurs.
The most common cause of cardiac arrest is coronary artery disease. Less
common causes include major blood loss, lack of oxygen, very low potassium,
heart failure, and intense physical exercise. A number of inherited disorders
may also increase the risk including long QT syndrome. The initial heart
rhythm is most often ventricular fibrillation. The diagnosis is confirmed by
finding no pulse. While a cardiac arrest may be caused by heart attack or heart
[.failure these are not the same
Risk factors:
Risk factors include: high blood pressure, smoking, diabetes, lack of exercise,
obesity, high blood cholesterol, poor diet, and excessive alcohol, Other risks
include depression
.
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