 Dear students, in this topic we shall discuss the cardiac output and stroke volume. Cardiac output is the quantity of blood pumped into the aorta each minute by the heart. The average cardiac output per resting adult human is about 5 liters per minute. Dear students, the cardiac output is affected by and varies widely with many factors including the basic level of body metabolism, the physical activity of the body, size of the body, age and gender. All these factors affect the cardiac output. Dear students, in comparison to cardiac output which is the quantity of a minute, in comparison to stroke volume, this is the volume of blood which is ejected from the heart by each beat of the heart. It is the difference between volume of the ventricle just before contraction, and the volume of the ventricle at the end of a contraction, and systolic volume. The stroke volume is determined by dividing the cardiac output by heart rate, mathematically when we calculate it, we divide the cardiac output by heart rate. Changes in a stroke volume result from changes in end diastolic or end systolic volume. The end diastolic volume depends on four parameters, number one, venous filling pressure, number two, pressure generated during arterial contraction, number three, distensibility, any expansion of the ventricular wall, and number four, the time available for filling the ventricle. The end systolic volume depends on two parameters, number one, the pressures generated during ventricular systole, and the pressure in the outflow chambers are channels, outflow channels that is aortic and pulmonary arteries.