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Heart:
a muscular double pump with two functions
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1) Right side:
receives oxygen poor blood and then pumps this blood to the lungs to pick up oxygen and dispel carbon dioxide (Pulmonary circuit)
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2) Left side:
receives the oxygenated blood from the lungs and pumps this blood throughout the body. (Systemic circuit)
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Atria (x 2):
superior chambers (separated by the interatrial septum) that receive blood returning from the pulmonary and systemic circuits.
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Ventricles (x 2):
inferior chambers (separated by the interventricular septum) that pump blood around the two circuits.
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The _____ lies in the thorax posterior to the sternum, left of the midline and rests on the superior surface of the diaphragm
heart
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Pericardium (“Around the heart”):
a triple layered sac
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Fibrous pericardium:
outer strong layer of dense connective tissue
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Serous pericardium, formed from two layers:
- 1) Parietal layer... fused to fibrous pericardium
- 2) Visceral layer (a.k.a. epicardium)
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Pericardial cavity:
Fluid-filled space between the parietal and visceral layers of serous pericardium.
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Pericardial cavity function:
contains a lubricating fluid that reduces friction between the beating heart and the outer wall of the pericardial sac.
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Epicardium:
visceral layer of the serous pericardium
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Myocardium:
- consists of cardiac muscle
- -Muscle arranged in circular and spiral patterns
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Endocardium:
- endothelium resting on a layer of connective tissue
- -Lines the internal walls of the heart
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Vessels returning blood to the heart:
Superior and inferior venae cavae and Right & Left Pulmonary veins
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Vessels conveying blood away from the heart include:
-Pulmonary trunk (which splits into right and left pulmonary arteries)
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Ascending aorta (three branches) –
brachiocephalic, left common carotid, and left subclavian artery
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The right atrium receives oxygen-poor blood from the superior and
inferior vena cava and the coronary sinus, and pumps it into the right ventricle through the tricuspid valve.
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-Internally, the right atrium has two parts: a smooth walled posterior part and an anterior part lined by horizontal ridges called the pectinate muscles
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Heart valves ensure ________ blood flow through the heart
unidirectional
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Each heart valve consists of two or three cusps, which are flaps of endocardium reinforced by cores of dense C.T.
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Heart valves open and close in response to
differences in blood pressure on each side of the valves
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The two atrioventricular valves (tricuspid and bicuspid valves) prevent
the backflow of the blood into the atria during contraction of the ventricles.
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When the ventricles are relaxed, the valves are forced open by the
blood pressure exerted on their atrial side
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When the ventricles start to contract, the pressure within them rises and forces the blood superiorly against the valve cusps...pushing the edges of the cusps
together and closing the AV valves
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The right ventricle receives oxygen-poor blood from the right atrium via the tricuspid valve, and pumps it into the
pulmonary arteries via the pulmonary semilunar valve and ] pulmonary trunk.
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Internally, the walls are marked with irregular ridges of muscle called
trabeculae carneae.
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Cone-shaped papillary muscles project from the walls into the
- ventricular cavity and attach to strong bands called
- chordae tendineae.
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The chordae tendineae attach to the flaps (cusps) of the tricuspid
valve
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The papillary muscles of the heart serve to limit the movements of the bucuspid and tricuspid valves. These muscles contract to tighten the chordae tendineae, which in turn prevent
inversion
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They brace the valves against the high pressure, preventing regurgitation of ventricular blood back into
the atrial cavities
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The ______ ______, or heart strings, are cord-like tendons that connect the papillary muscles to the tricuspid valve and the bicuspid valve in the heart.
chordae tendineae
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-The chordae tendineae prevents the flaps from being everted into the
right atrium
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The two semilunar valves (pulmonary and aortic valves) prevent
- backflow from the great arteries into the
- ventricles
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The left atrium receives oxygenated blood returning from the lungs via the pulmonary veins, and pumps it into the
left ventricle
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The left ventricle receives oxygenated blood from the left atrium via the bicuspid valve, and pumps it into the aorta via the
aortic semilunar valve
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Like the right ventricle, it contains trabeculae carneae, papillary muscles, chordae tendineae, and the cusps of the bicuspid valve (mitral valve)
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Coronary circulation is the
functional blood supply to the heart muscle itself.
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Collateral routes ensure blood delivery to heart even if major vessels are
occluded
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