AMA 178 - Anatomy &
Physiology/Medical
Terminology/Pathology 9
Cardiovascular System
Function:
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Composed of the heart, a powerful
muscular pump, and blood vessels that
send oxygen and nutrients to all parts
of the body via the bloodstream.
Waste products are also eliminated
from body tissues via the bloodstream.
Structure of the Cardiovascular
System: Blood vessels
Three types of blood vessels: arteries, veins and
capillaries
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Arteries: large blood vessels that carry oxygen rich
blood away from the heart
Veins: carry deoxygenated blood to the heart from
the tissues, and waste products to other systems of
the body to be released
Capillaries: delicate, microscopic vessels that carry
nutrient rich, oxygenated blood from the arteries to
the body cells
Blood Circulation:
Pulmonary Circulation:
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Oxygen poor blood from body tissues enters the right
side of the heart via the venae cavae (2 large veins)
where it travels into the pulmonary artery (only
artery in the body that carries oxygen poor blood);
this branches into two sections, one to each lung.
Blood passes into the pulmonary capillaries where it
picks up oxygen rich blood and then goes back
through the heart to be pumped to all areas of the
body.
Blood Circulation:
Systemic Circulation:
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Oxygen rich blood enters the left side of the heart from the
pulmonary veins.
Blood is pumped via the aorta (largest artery in the body) to
other arteries that branch out to all parts of the body via tissue
capillaries near body cells, where nutrients are broken down in
the presence of oxygen and energy is released.
This chemical process releases carbon dioxide as a waste
product; this is taken back to the lungs and the body releases it
via exhalation.
Other wastes are taken by the veins to be eliminated by other
systems in the body.
Structure of the Cardiovascular
System: Heart
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Located in the thoracic cavity between the
lungs.
Weighs less than a pound and is about the
size of a human fist.
It is a pump consisting of four chambers and
four valves; its action is controlled by
electrical impulses initiating in the cardiac
muscle tissue.
Anatomy of the Heart:
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Atria: upper chambers of the heart
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Ventricles: lower chambers of the heart
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Superior vena cava: drains deoxygenated blood from the upper portion
of the body
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Inferior vena cava: carries deoxygenated blood from the lower
portion of the body
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Tricuspid valve: valve between the right atrium and right ventricle
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Pulmonary valve: valve between the right ventricle and the pulmonary
artery
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Mitral valve: valve between the left atrium and left ventricle
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Aortic valve: valve between the left ventricle and the aorta
Two Phases of the Heartbeat:
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Cardiac cycle: occurs 70-80 times a minute
(100,000 times a day). Heart pumps
approximately 3 ounces of blood with each
contraction (5 quarts a minute)
Diastole: relaxation – ventrical walls relax
and blood flows into heart from the venae
cavae and pulmonary veins
Systole: contraction – ventrical walls
contract pumping blood into the pulmonary
artery and aorta to all parts of the body
Conduction System of the Heart:
Electrical impulse originates in a small region of specialized muscle
tissue (SA node) and is sent in waves through the heart causing
contraction of ventricals
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Sinoatrial node (SA node): pacemaker of the heart; generates
current of electricity that causes atria to contract fording
blood into the ventricles
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Atrioventricular node (AV node): electrical impulse goes here
from the SA node and on to the bundles
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Bundle of His: bundle of specialized fibers that send impulse to
the left and right bundle branches
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Left & Right bundle branches: form the conduction myofibers
(electrical muscle tissue) that extend through ventricle walls
and stimulate them to contract.