HUMAN HEART AND ITS FUNCTIONING -BIOLOGY- TNPSC,TET,RRB,SSC SCIENCE (GK) STUDY MATERIAL

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

Artery Vein Capillary
Transports blood away from the
heart
Transports blood towards the heartLink arteries to veins.
Except where
they leave heart
Semilunar valves
No semilunar
valves
Blood oxygenated except in pulmonary
artery
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
    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
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