In general, any decrease in venous return will lead to reduced stroke volume (e.g. Cardiac output is the multiple of stroke volume times heart rate. The Frank-Starling curve demonstrates how changes in ventricular preload (i.e. What is the Starling curve and what is its importance in the management of shock? While low cardiac output and resting vascular tone are appropriate while the individual is at rest, a higher cardiac output and decreases in vascular tone are required to meet the metabolic demands of activity or stress. Metabolic waste products are transported back to central circulation in the venous system along with deoxygenated blood.Īdditionally, the heart and the circulatory system respond to changes in the metabolic demand of the individual. Oxygenated blood is transported by arteries of diminishing size to end organs where it is extracted for aerobic metabolism. The components of the circulatory system include arteries, arterioles, capillaries, venules and veins. This oxygenated blood returns to the left atrium via the pulmonary veins after which it is pumped by the left ventricle to the body via the systemic arterial circulation. From here, it is pumped to the lungs via the pulmonary arteries where it becomes oxygenated. Deoxygenated blood from the systemic venous system (inferior and superior venae cavae) returns to the right atrium where it passes into the right ventricle. What is the normal function of the heart and the circulation?Ī normally functioning heart pumps blood to both the pulmonary and systemic circulations, which are connected in series. Neonatal cardiovascular physiology is different than older infants and children and therefore is managed differently. An understanding of normal cardiovascular physiology, oxygen dynamics and compensation mechanisms is required to understand cardiovascular dysfunction.