Download The-Circulatory

How animals stay alive part 3
• 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.
• 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.
• 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.
• 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
• 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.