Post on 02-Jun-2018
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HEARTAND
ITS STRUCTURE
SUBMITTED BY SUBMITTED TODIVYA SIVADASAN DIVYA.S
NATURAL SCIENCE (LECTURER)13375010
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In human being heart is situated in thoracic cavityunder the breast bone and between the lungs.
A persons heart generally as large as his/her fist .
It is 12cm long and 9cm wide and weigh 300gm.
It is surrounded by a double layered membranecalled pericardium. In between these layer is afluid called pericardial fluid.
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BLOOD VESSELS ARISING FROM
HEART
Blood vessels that carry blood to theheart are Veins
Blood vessels that bring blood to heartfrom different parts of the body are Arteries
Pulmonary vein, Superior Vena Cava,Inferior Vena Cava, Pulmonary artery
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CHAMBERS IN THE HEART
Heart has four chambers.The upper two chambers are right
atrium and left atrium .The lower chambers are right ventricle
and left ventricle.
The atria and ventricles are separatedby muscular wall.
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VALVES PRESENT IN THE HEART
Valve in between right atrium and rightventricle is Tricuspid valve.
Valve in between left atrium and rightventricle is Bicuspid valve.The opening of the aorta from the left
ventricle are guarded by valves calledSemilunar valves.
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The right half of the heart contains onlydeoxygenated blood or impure blood .The left half of the heart containsoxygenated blood or pure blood .
The wall of the ventricles are thickerthan atria.Left ventricles are thick because it
supplies oxygenated blood to wholebody.
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WORKING OF THE HEART
From different parts of the body blood reaches toright atrium through superior and inferior venacava.
From lungs oxygenated blood reaches to left atrium through Pulmonary vein .When blood reaches the atrium, it contractsblood enters the ventricle.When ventricle contracts, deoxygenated blood inthe right ventricle enters the lungs through
pulmonary artery
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When ventricle contracts, deoxygenated bloodin the right ventricle enters the lungs through
pulmonary artery. Blood gets oxygenated in the lungs.
Oxygenated blood in left ventricle reachesdifferent parts of the body through Aorta. This blood release oxygen and receive carbon
dioxide . Then it reaches right atrium through vena
cava and the process continues.
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HEART BEAT
Contraction of heart is known as Systole . Relaxation of heart is known as diastole . A Systole and Diastole constitute Heart
Beat . The normal beat rate is 72 per minute . The time taken for one contraction and
relaxation of the heart is 0.8 seconds .
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BLOOD PRESSURE
As the heart contracts and pushes the blood, thepressure causes the arteries to distend toaccommodate the incoming blood. This pressure is
called Systolic pressure (120mm/hg). When the ventricle relaxes, the pumping of blood
into the arteries stops. This pressure is calledDiastolic pressure (80mm/hg).
It can be measured by an instrument calledSphygmanometer.
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