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Coronary Circulation

Anterior atrtal branch ot righi coronary artery

CARDIOYASCULAR PHYSIOLOGY

Sinuatrial ISA) notlal branch

anerv Postcrior int€rventricular post. riescending) branch of righi coronary artery

Time (seconds)

Figurę 4.12 Coronary Circulation_

The coronary arteries c orne off the aorta just above the aortit valve. Coronary blood flow varies with aortic pressure but is intluenced by physical factors (compression of the ve$sels during contraction of the heart) and by metabolit factors rełeased from the myocytes. Nlumer-ous metabolic factors havc been implicated in tht* regulation of coronary blood flow (e.g.. H \ CO.., decreased O.., K'. lat lic at.id, nilrit oxide, adenosine). Of these factors, adenosine seems to be the most important. Thus. when cardiac work demand increases. adenosine releaserJ by the myocytes leads to vasodilalion and thereby increased coronary blood flow.

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