Cardiac Output, Venous Return, and Their Regulation به نام خدا Cardiac Output, Venous Return, and Their Regulation Dr.Radmanesh

The factors directly affect cardiac output (1) the basic level of body metabolism (2) whether the person is exercising (3) the person’s age (4) size of the body Dr.Radmanesh

Cardiac Index the cardiac output per square meter of body surface area. The normal human being weighing 70 kilograms has a body surface area of about 1.7 square meters, normal average cardiac index for adults is about 3 L/min/m2 of body surface area. Dr.Radmanesh

Effect of Age on Cardiac Output Dr.Radmanesh

Dr.Radmanesh

Role of the Frank-Starling Mechanism of the Heart Dr.Radmanesh

Effect of Total Peripheral Resistance on the Long-Term Cardiac Output Level Dr.Radmanesh

Ohm’s law Dr.Radmanesh

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Factors That Can Cause Hypereffective Heart Effect of Nervous Excitation to Increase Heart Pumping. sympathetic stimulation parasympathetic inhibition Increased Pumping Effectiveness Caused by Heart Hypertrophy A long-term increased workload, but not so much Dr.Radmanesh

Factors That Cause a Hypoeffective Heart Coronary artery blockage, causing a “heart attack” Inhibition of nervous excitation of the heart Pathological factors that cause abnormal heart rhythm or rate of heartbeat Valvular heart disease Increased arterial pressure against which the heart must pump, such as in hypertension Congenital heart disease Myocarditis Cardiac hypoxia Dr.Radmanesh

Importance of the Nervous System in Maintaining the Arterial Pressure When the Venous Return and Cardiac Output Increase Dr.Radmanesh

Effect of the Nervous System to Increase the Arterial Pressure During Exercise Dr.Radmanesh

Pathologically High and Pathologically Low Cardiac Outputs Dr.Radmanesh

High Cardiac Output Caused by Reduced Total Peripheral Resistance Beriberi Arteriovenous fistula (shunt) Hyperthyroidism Anemia Dr.Radmanesh

Low Cardiac Output Decreased Cardiac Output Caused by Cardiac Factors severe coronary blood vessel blockage and consequent myocardial infarction severe valvular heart disease myocarditis cardiac tamponade cardiac metabolic derangements Decrease in Cardiac Output Caused by Non-cardiac Peripheral Factors—Decreased Venous Return Decreased blood volume Acute venous dilation Obstruction of the large veins Decreased tissue mass, especially decreased skeletal muscle mass. Dr.Radmanesh

Venous Return Curves Dr.Radmanesh

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Effect of Blood Volume on Mean Circulatory Filling Pressure Effect of Sympathetic Nervous Stimulation of the Circulation on Mean Circulatory Filling Pressure Dr.Radmanesh

Effect on the Venous Return Curve of Changes in Mean Systemic Filling Pressure Dr.Radmanesh

“Pressure Gradient for Venous Return” When This Is Zero, There Is No Venous Return the greater the difference between the mean systemic filling pressure and the right atrial pressure, the greater becomes the venous return. Dr.Radmanesh

Effect of Resistance to Venous Return on the Venous Return Curve Dr.Radmanesh

Resistance to Venous Return VR is venous return Psf is mean systemic filling pressure PRA is right atrial pressure RVR is resistance to venous return 1.4 mm Hg per liter of blood flow. Dr.Radmanesh

Dr.Radmanesh

Dr.Radmanesh

Effect of Increased Blood Volume on Cardiac Output Dr.Radmanesh

Effect of Sympathetic Stimulation on Cardiac Output Dr.Radmanesh

Effect of Opening a Large Arteriovenous Fistula Dr.Radmanesh