Cardiovascular System Circulation

Valves ensure blood does not flow back into the atria & ventricles : Right Atrium  Tricuspid Valve  Right Ventricle  Pulmonary Semilunar Valve  Pulmonary Artery/Arterioles  Lungs (Pulmonary Capillaries)  Pulmonary Venules /Veins  Left Atrium  Bicuspid/Mitral Valve Left Ventricle  Aortic Semilunar Valve  Aorta  Body

A PA A

Revisit Systole & Diastole

Once leaving the heart, the blood must make its way back: Left Ventricle  Aortic Semilunar Valve  Aorta  Arteries  Arterioles (O2)  Systemic Capillaries  (Gas Exchange: O2 /CO2) Venules (DeO2)  Veins  Superior & Inferior Vena Cavae (Cava-s)  Right Atrium

Differences in Vessels Arteries (“A” for “away”) ALWAYS carry blood AWAY from the heart USUALLY carry oxygenated blood Have thicker walls than veins Veins ALWAYS carry blood TO the heart USUALLY carry deoxygenated blood Have valves

Differences in vessels, cont’d Capillaries: Exchange O2 for CO2 at body cells and CO2 for O2 at the lungs Are microscopic, walls only one cell thick--allowing for the above

Arteries usually carry oxygenated blood, veins usually carry deox - what’s the exception? Heart  pulmonary artery(deO2)  pulmonary arterioles (deO2 )  capillaries of lungs, where blood becomes oxygenated Capillaries of Lungs  pulmonary venules (O2)  pulmonary veins (O2)  heart

Finalize the loop Now that you have been introduced to all components of the circulatory loop, put them all together to show exactly where blood travels. Indicate whether the blood is oxygenated (O2) or deoxygenated (DeO2) and where gas exchange occurs.

The Loop Right Atrium (deoxygenated) Tricuspid Valve Right Ventricle Pulmonary Semilunar Valve Pulmonary Artery Pulmonary Arterioles Pulmonary Capillaries (CO2 dropped off O2 picked up) Pulmonary Venules (oxygenated) Pulmonary Veins>>>> Left Atrium Bicuspid/Mitral Valve Left Ventricle Aortic Semilunar Valve Aorta Systemic Arteries Systemic Arterioles Systemic Capillaries (O2 dropped off, CO2 picked up) Systemic Venules (deoxygenated) Systemic Veins Superior/Inferior Vena Cava

Looking at this loop… Why do you think that it is important that arteries have thicker walls than veins? Arteries have thicker walls to withstand the high pressure of the blood coming from the heart -- caused by the heart’s contractions.

Looking at this loop… Why do you think that it is important that veins have valves? By the time blood reaches the veins, its velocity and pressure have decreased. Valves prevent the backflow of blood.

Blood return to the heart is affected by Valves A strongly beating heart Adequate arterial blood pressure “Milking action” of skeletal muscle contraction Changing pressures in the chest cavity caused by breathing

The heart & blood vessels are important in supplying the cells of the body with O2. But… What about the cardiac tissue itself? How does the heart get the O2 that it needs?