• The  heart is located in the media sternum about to third of its mass is to the left of midline.
  • The heart is shaped like a lone lying of its sides, its apex is the pointed, inferior part, where as its base is the broad, superior parts.
  • The pericardium is the membrane that surrounds the heart and protect the heart. It consist of an outer fibrous layer & inner serous pericardium, which is comfort of a parietal and visceral layer.
  • Between the parietal & visceral layer of the serous pericardium is the pericardial cavity, A potential space filled with a few m.l of pericardial fluid that reduce friction between to the  membrane.
  • Three layer make up the valve of heart-
  •  Epicardium (Visceral layer  of the serous pericardial).
  • Myocardium
  • Endocardium
  • The epicardium consist of mesothelium and connective tissue the  myocardium is composed of cardiac muscles tissue & endocardium consist of endothelium & connective tissue.
  • The heart chamber include two superior chamber, the right and left atria or oricod and two inferior chamber the right and left ventricle.
  • External feathers of the heart include coronary sulcus between the atria and ventricle, anterior  and posterior sulci between the ventricle on the anterior and posterior surface of the heart.
  •  The right atrium obtain blood from the superior vena cava , inferior vena cava and coronary sinus. It is separated for the left atrium by the inter atrium septum , which contain the foci ovals. The blood come into right ventricle from right  atrium  bi, tri cuspid valve.
  •  The right ventricle which received the blood from right atrium. It is separated from the left ventricle by inter ventricle septum   and pump blood from right ventricular to lungs by pulmonary artery or pulmonary trunk.
  • Oxygenated blood enter the left atrium by pulmonary vein which carry pure blood from lungs. The pure blood come into left ventricle viva bicuspid or mitral valve.
  • The left ventricle pump the blood which are oxygenated into aorta through the aortic valve which is semi lunar valve.
  • The  thickness of the myocardium of the four chamber varies according to the chamber functions. The left ventricle which have highest work load the thickest wall.
  • The fibrous selection of the heart of the dense connective tissue that surround and support the wall of the blood.

Heart valve and circulation of blood:

  • The valve prevent back flow of blood with in the heart the atrio-ventricular valve /AV valve which lay down between the atria and ventricles are the tricuspid valve on the right side of the heart and bicuspid valve (metered valve) on the left side. The semi lunar valve/ SL valve are the aortic valve at the  entrance of aorta and the pulmonary valve at the entrance of pulmonary trunk.
  • The left side of the heart is the pump of blood for systemic circulation , the circulation of blood through out the body except for the air sacs of the lung. The left ventricle pump blood into aorta, and blood them flow into systemic arteries, arterials, capillaries, venules and vein .  Which carry it back to the right atrium.
  • The right side of the heart is pump blood for pulmonary circulation, the circulation of blood through lungs. The right ventricles pump blood into pulmonary trunk , and blood than flow into pulmonary arteries, pulmonary capillaries and pulmonary vein which carry it back to the left atrium.
  • The corollary circulation provide blood flow to the myocardium. The main arteries of the corollary circulation are the right and left arteries the main vein are the cardiac vein and corollary sinus.

Cardiac Cycle:

  • A cardiac cycle consist of the systole (contraction) and diastole (relaxation) of both atria , plus the systole and diastole ventricular. With as average heart beat of 72 beats/ min. a complete cardiac cycle required 0.8 seconds.
  • A phase of cardiac cycle are atrial systole , ventricular systole.
  • S1 the first heart sound (lube) is caused by turbulence associated with the closing of the atrio ventricular valve. S2 the second heart sound dub is caused by the turbulence associated with closing of semi lunar valve.

Bhanu Pratap Singh


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