1. How animals stay alive part 3

2. Animals breathe in oxygen using their lungs or their gills. Once the oxygen gets into their lungs or gills, how does it get to the rest of the body? Answer: The circulatory system transports oxygen from the lungs/gills to the rest of the body and gets rid of carbon dioxide The circulatory system transports blood through the body.

3. All circulatory systems have a set of tubes and one or more pumps The tubes are called blood vessels The pumps are called hearts When the heart contracts (pulls together) it squeezes blood through the blood vessels.

4. There are 2 types of circulatory systems: Closed and Open Arthropods and most mollusks have an open circulatory system. In this system, blood leaves the vessels and enters spaces around the organs. The blood flows slowly though the spaces and makes direct contact with the cells.

5. Some invertebrates, like segmented worms, have closed circulatory systems. In a closed circulatory system, the blood stays inside vessels at all times. The smallest vessels have very thin walls. Oxygen and carbon dioxide diffuse (travel though one material to another) in or out of the blood across these walls

6. Vertebrates only have one heart The heart is divided into closed spaces called chambers. The atria are chambers that receive blood that returns to the heart. The ventricles are chambers that pump blood out of the heart.