2. beginning with the superior vena cava, trace the path followed by a red blood cell as it passes into and through the heart, to the lungs, back to and through the heart, and to the rest of the body. name each heart chamber, valve, and large blood vessel in the pathway.

BLOOD PATHWAY:

Body > superior and inferior vena cava > right atrium > tricuspid valve > right ventricle > pulmonary semilunar valve > pulmonary artery > lungs > pulmonary vien > left ventricle > bicuspid/mitral valve> left ventricle > Aortic semilunar valve > Aorta > Body

The pathway goes like this:

From the body (we don't say first because this is a cycle), unoxygenated blood collected goes to the heart via the INFERIOR and SUPERIOR VENA CAVA then it empties into the RIGHT ATRIUM from there it passess through a valve called TRICUSPID valve, which prevents backflow of blood to the right atrium. The blood goes to our first pumping chamber, RIGHT VENTRICLE. The right ventricle pumps the blood through the PULMONARY SEMILUNAR VALVE which leads to the PULMONARY ARTERIES, which happens to be the only arteries that carry unoxygenated blood. From there it goes to the lungs to pick up oxygen and rid itself of carbon dioxide. The blood then goes back into the heart via the PULMONARY VEINS and like the latter, they are the only veins that carry oxygenated blood.

The blood then goes back into the heart, emptying into the LEFT ATRIUM. From there it goes through the BICUSPID VALVE or MITRAL VALVE and to the last and thickest pumping chamber, the LEFT VENTRICLE. The left ventricle pumps the blood through the AORTIC SEMILUNAR VALVE which opens out to the AORTA.

And at last, it goes back to your body.

b. the carbon cycle ensures living things have a source of hydrogen

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