Describe how heart contraction and relaxation influence coronary blood flow?

Answer 1

When relaxation or diastole is occurring in the atria blood flows through the atria and the AV valves into the ventricles. When contraction or systole is occurring in the atria the remaining blood that doesn't flow through during relaxation is pushed into the ventricles. As the atria relax, the ventricles begin contracting; ventricular pressure rises, closing the AV valves. Ventricular pressure continues rising until it exceeds the pressure in the large arteries stemming from the ventricles. The SL valves are forced open and blood is expelled from the ventricles into the aorta and pulmonary trunk. During this phase the ventricles relax because the blood is no longer compressed in their chambers. Blood expelled into the aorta and pulmonary trunk backflows toward the heart, which then closes the SL valves. During the ventricle contraction the atria stays in relaxation, filling with blood and when blood pressure on the atrial side of the AV valves exceeds that in the ventricles, the AV valves are forced open and ventricular filling begin all over again.