HUMAN HEART AND ITS FUNCTIONING
* Size 12 x 9 cm and 300 gm weight. * Enclosed in a tough, 2 layer connective tissue sac, the pericardium.
* Has 4 chambers: 2 upper smaller auricles and 2 lower larger ventricles.
* The right auricle opens into right ventricle through tricuspid valve.
* This blood vessel is guarded by semi-lunar valve to prevent backflow of blood into ventricles.
* Blood again returns to heart from the lungs in left auricle. Now the blood is oxygenated.
* The left auricle opens into the left ventricle through a bicuspid valve.
* From the left ventricle the blood flows throughout the body through a large blood vessel callec aorta.
* To pump-out blood, the heart chambers undergo alternate contraction called systole and relaxation called diastole.
COMPARISON OF ARTERY, CAPILLARY
|Transports blood away from the|
|Transports blood towards the heart||Link arteries to veins.|
they leave heart
|Semilunar valves||No semilunar|
|Blood oxygenated except in pulmonary|
|Blood deoxygenated except in pulmonary vein||Mixed oxygenated and deoxygenated blood.|
- Lubbis produced by the closing of tricuspid
and bicuspid valves while dupp is produced
by the closing of semi-lunar valves.
- This patch is the sino-auricular node which
is called the pacemaker. Normal heart beat is
- Heart failure: When S.A. node does not initiate any impulse.
- Sphygmomanometer measure the B.P. BP is 120/80 mm of Hg.
- Pulmonary artery: The only artery which carries
deoxygenated blood. It carries blood from right
ventricle to lungs.
- Pulmonary vein: The only vein which carries
oxygenated blood. It carries blood from lungs to left