Changes

==Circulatory==

==Circulatory==

The heart, arteries, veins, and capillaries.

The circulatory system interface with the respiratory system to pump oxygenated blood throughout the body, thus supplying the organs with nutrients. The circulatory system consists of the heart and blood vessels. The heart is a special muscle which constantly and automatically pumps blood through the blodo vessels.  The blood vessels consist of arteries, arterioles (smaller arteries), capillaries, venules (small veins), and veins. Arteries carry blood away from the heart, whereas veins carry blood to the heart. Normally arteries carry oxygenated blood and the veins normally carry oxygen-poor blood, but this is not always the case, as with the pulmonary arteries and veins which carry blood back and forth between the heart and lungs. Capillaries are the smallest blood vessels and are where oxygen exchange between blood and organs takes place.

==Immune and Lymphatic==

==Immune and Lymphatic==