Cardiovascular SystemCirculation

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

PA

A

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 VesselsArteries (“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’dCapillaries:

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 loopNow 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 Loop1. Right Atrium

(deoxygenated)2. Tricuspid Valve3. Right Ventricle4. Pulmonary Semilunar

Valve5. Pulmonary Artery6. Pulmonary Arterioles7. Pulmonary Capillaries

(CO2 dropped off O2 picked up)

8. Pulmonary Venules (oxygenated)

9. Pulmonary Veins>>>>

10. Left Atrium11. Bicuspid/Mitral Valve12. Left Ventricle13. Aortic Semilunar Valve14. Aorta15. Systemic Arteries16. Systemic Arterioles17. Systemic Capillaries (O2

dropped off, CO2 picked up)

18. Systemic Venules (deoxygenated)

19. Systemic Veins20. 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 byValvesA strongly beating heartAdequate arterial blood pressure“Milking action” of skeletal muscle

contractionChanging 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?