A double circulatory system - 2 circuits joined together
First one pumps deoxygenated blood to the lungs to take in
oxygen. The blood then returns to the heart.
The second pumps oxygenated blood
around all the other organs of the body. The
blood gives up its oxygen at the body cells
and the deoxygenated blood returns to the
heart to be pumped out to the lungs again.
The heart contracts to pump blood around the body
The heart is a pumping organ that keeps the blood flowing
around the body. The walls are mostly made of muscle tissue.
This is how the heart uses its 4 chambers (right, left
atrium , right,left ventricle to pump blood around
1 - blood flows into the 2 atria from the vena cava and
the pulmonary vein. 2 -The atria contract, pushing the
blood into the ventricles. 3- The ventricles contract,
forcing the blood into pulmonary artery and the aorta,
and out of the heart. 4- blood then flows to the organs
through arteries and returns through veins. 5- The atria
fill again and the whole cycle starts over
The heart has valves to make sure that blood goes in
the right direction - to prevent it flowing backwards.