Directions: Using the web site Human Anatomy Online, fill in the following paragraphs with the correct words.

The cardiovascular system includes the __________t and the _________ __________. The heart pumps blood, and the blood vessels channel and deliver it throughout the body. ___________ carry blood filled with nutrients away from the heart to all parts of the body. The blood is sometimes compared to a river, but the arteries are more like a river in reverse. Arteries are thick-walled tubes with a circular covering of yellow, elastic fibers,which contain a filling of muscle that absorbs the tremendous ____________ wave of a _________________ and ________ the blood<BR>

down. This pressure can be felt in the arm and wrist it is the ______________.

Eventually arteries divide into smaller _____________ and then into even smaller _________________, the smallest of all blood vessels. One arteriole can serve a________________capillaries. Here, in every tissue of every organ,___________ work is done when it gives up what the cells need and takes away the ____________ products that they don't need.

Now the river comparison really does apply. Capillaries join together to form small veins, which flow into______________ main

___________, and these deliver _____________________ blood back to the heart. ____________, unlike arteries, have __________, slack walls, because the blood has lost the pressure which forced it out of the heart, so the dark, reddish-blue blood which flows through the veins on its way to the lungs___________ along very slowly on its way to be ____________________. Back at the heart, the veins enter a special vessel called the pulmonary arteries, into the wall at ____________ side of the heart. It flows along the pulmonary arteries to the lungs to collect oxygen, then back to the heart's left side to begin its journey around the body again.