Cardiovascular Organization and the Heart
Pulmonary circuit - carries blood to and from the lungs
Systemic circuit - carries blood to and from the rest of the body
Pulmonary Arteries - carry blood away from the heart to the lungs
Pulmonary Veins - carry blood from the lungs to the heart
Systemic Arteries - carry blood from heart to other organs
Systemic veins - carry blood from other organs to the heart
Lymphatic vessels - carry lymph from tissues to systemic veins
Interstitial space - space between cells and between cells and the smallest blood vessels (the capillaries)
Interstitial fluid - fluid surrounding cells of tisues
fluid moves between blood and the interstitial space, and between the interstitial space and cells
thin walled vessels between the smallest arteries and veins where exchange of oxygen, nutrients, wastes and other substances occurs between the blood and the interstitial fluid.
recovers plasma lost from the blood capillaries for return to the systemic venous circulation (lymphatic system also collects, captures and destroys pathogens in the body)
Relationship between the Heart and Blood Vessels
Right atrium - receives blood from the systemic circuit via the Inferior and Superior Vena Cava
Right ventricle - discharges blood into pulmonary circuit via the Pulmonary Trunk and Pulmonary Arteries
Left atrium - receives blood from the pulmonary circuit via the Pulmonary Veins
Left ventricle - discharges blood into systemic circuit via the Aorta
Right atrioventricular valve - controls movement of blood between the right atrium and right ventricle (tricuspid valve)
Pulmonary semilunar valve - controls movement of blood between the right ventricle and the pulmonary circuit
Left atrioventricular valve - controls movement of blood between the left atrium and the left ventricle (bicuspid valve, mitral valve)
Aortic semilunar valve - controls movement of blood between the left ventricle and the systemic circuit
The Heart as a Pump
Cardiac cycle - period between one heart beat and the next
Systole - during contraction
Diastole - during relaxation
Blood moves from one chamber to the next only if the pressure in the first chamber exceeds that in the second.
leads to a decrease in atrial pressures.
As the atrial pressures become less than the venous pressures, blood moves from the veins to the atria.
leads to a rapid decrease in ventricular pressure.
As the ventricular pressures become less than the arterial pressures, the semilunar valves close.
As the ventricular pressures become less than the atrial pressures, the atrioventricular valves open and blood moves from the atria to the ventricles.
The diastolic pressure differences between the atria and the ventricles leads to about 70% of ventricular filling.
leads to a rapid increase in atrial pressures.
As the atrial pressures increase, more blood moves from the atria to the ventricles
leads to a rapid increase in ventricular pressure
As the ventricular pressures exceed the atrial pressures, the atrioventricular valves close.
As the ventricular pressures exceed the arterial pressures, the semilunar valves open and blood moves to the arteries.
© David G. Ward, Ph.D. Last modified by wardd 23 May, 2006