PULMONARY CIRCULATION::
It is a short circuit which arises from the right ventricle and carries the venous blood to the lungs for purification oxygenated (purified) blood goes to the left atrium the pulmonary circuit is from the right ventricle to the left atrium with interposition of the lungs the pulmonary trunk arises from the right ventricle and divides into 4 pulmonary arteries which pour the blood in lungs the blood is collected from the lungs through four pulmonary veins which open directly into the left atrium the pressure in pulmonary arteries is about 40 to 50 mmHg
CORONARY CIRCULATION::
It is circulation of blood to the heart first branch of aorta at start is the coronary artery which supplies the blood to the heart muscle itself it has right branch and a left branch Further ramifications of these vessels occur in the wall of the heart the anastomosis is poor in coronary vessels the coronary arteries are functionally the end arteries in a healthy individual there is little communication between larger branches of the coronary arteries that is why when a vessel is obstructed by a thrombus the circulation to that part of the heart generally fails with very serious consequences endangering life however collateral circulation generally develops in patients who have a past history of infarcts
The coronary venules form the coronary vein which opens in the coronary sinus of the right atrium the coronary venous system is superficial as well as deep in the myocardium
The blood pressure in coronary arteries is very high about 250 ml of blood (5% of the cardiac out put ) is supplied to the heart itself cardiac muscle shows maximum oxygen extraction when the person is taking rest heart connot bear with the oxygen debt and has a limited capacity for anaerobic metabolism the increased demand of oxygen can only be fulfilled by increased blood low through coronary arteries the coronary circulation has a very large reserve and the coronary flow can increase upto 500% of the resting value during exercise
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