Multiple choice The cardiac output increases by the hormone aldosterone released from the adrenal medulla increases by stimulation of the vagus nerve is calculated as the ratio of oxygen consumption and the difference in PO2 of the venous and arterial blood is mainly actuated by the end-diastolic volume of the blood Reveal answer Fill a bubble to check yourself D Correct answer Explanation Cardiac output is the volume of blood pumped by the heart per minute. It is mainly determined by the end-diastolic volume of the blood.