HUMAN HEART AND ITS FUNCTIONING

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 AND VEIN
 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 72/min.
 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 auricle.