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The heart is the driver of the circulatory system, pumping blood through rhythmic contraction and relaxation. The rate of blood flow out of the heart (often expressed in L/min) is known as the cardiac output (CO). Blood being pumped out of the heart first enters the aorta, the largest artery of the body.
Cardiac physiology or heart function is the study of healthy, unimpaired function of the heart: involving blood flow; myocardium structure; the electrical conduction system of the heart; the cardiac cycle and cardiac output and how these interact and depend on one another.
Blood is a non-Newtonian fluid. However, often the non-Newtonian effect is very small due to various reasons. Thus, it is important to know about the blood rheology. One of the characteristics of blood that affects the work required to cause the blood to flow through the arteries is the viscosity of blood.
Instead of blood flowing through the pulmonary artery to the lungs, the sphincter may be contracted to divert this blood flow through the incomplete ventricular septum into the left ventricle and out through the aorta. This means the blood flows from the capillaries to the heart and back to the capillaries instead of to the lungs.
Increasing blood flow to the surface (e.g., during warm weather or strenuous exercise) causes warmer skin, resulting in faster heat loss. In contrast, when the external temperature is low, blood flow to the extremities and surface of the skin is reduced and to prevent heat loss and is circulated to the important organs of the body, preferentially.
When blood vessels dilate, the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output [further explanation needed]. Vascular resistance is the amount of force circulating blood must overcome in order to allow perfusion of body tissues. Narrow vessels create more vascular resistance, while dilated ...
The cold water can cause heart attack due to severe vasoconstriction, [2] where the heart has to work harder to pump the same volume of blood throughout the arteries. For people with pre-existing cardiovascular disease , the additional workload can result in myocardial infarction and/or acute heart failure , which ultimately may lead to a ...
The upper two chambers, the left and right atria, are entry points into the heart for blood-flow returning from the circulatory system, while the two lower chambers, the left and right ventricles, perform the contractions that eject the blood from the heart to flow through the circulatory system.