Discuss the hemodynamics of blood flow through the systemic system during exercise

Answer 1

Blood flows down a pressure gradient from the high pressure of the left side of the heart to the low pressure of the right side of the heart. The flow of blood between the left side of the heart and the right side of the heart is directly proportional to the pressure difference between the left ventricle and the right atrium. Also, increases in blood flow are achieved by decreasing resistance, or the TPR, of the circulation in a greater proportion than by increasing the pressure. Resistance is directly proportional to the length of the vessel and to the viscosity of the blood, and is inversely proportional to the fourth power of the radius. Resistance is reduced when local metabolic activity results in vasodilation caused by reductions in tissue PO2, breakdown of ATP-producing adenosine, increased shear stress on the endothelium-releasing NO, and an endothelium-derived vasodilating factor caused by increases in blood flow. Much of the vasodilation is a result of the metabolic factors causing hyperpolarization of the potassium ATP (KATP) channels of the smooth muscle cells, resulting in K ion efflux and inhibition of the Ca2 ion influx into the cell via the calcium channel.