Circulatory System - Notes, Biology | IBPS PO Prelims & Mains Preparation - Bank Exams PDF Download

CIRCULATORY SYSTEM

Human Heart

Human Heart and its Functioning;-

• Enclosed in a tough, 2 – Layered Connective Tissue Sac, the Pericardium.
• Has 4 Chambers : 2 upper Smaller Auricles and 2 Lower Larger Ventricles.
• The right auricle receives 2 Large Veins : superior vena cava and inferior vena cava.

• The right auricle opens into right ventricle through tricuspid valve.
• The right ventricle gives off a large blood vessel which carries deoxygenated blood to the lungs.
• 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 left ventricle through a bicuspid valve.

• From the left ventricle the blood flows throughout the body through a large blood vessel called aorta.
• It is again guarded by semi – lunar valves to prevent back – flow of blood.
• To pump – out blood, the heart chambers undergo alternate contraction called systole and relaxation called diastole.
• The regular sequence of these systole and diastole causes the heart sound LUBB and DUPP.

• Lubb is produced by the closing of tricuspid and bicuspid valves while dupp is produced by the closing of semi – lunar valves.
• Our heart – beat is myogenic in nature ie, it is initiated by a patch of modified heart muscles itself without requiring an external stimulation.
• Normal heart beat is 72 /min.
• Heart Failure : When S.A. node does not initiate any impulse.
• Sphygmomanometer measure the BP. There are 2 limits of BP :
  • Higher Limit
  • Lower Limit
• Higher limit is the systolic BP at the time of ventricular systole while lower limit is the diastolic BP at the time of ventricular diastole. BP is 120/80 mm of Hg.

Diseases of Heart