11. The Purpose of the Heart The human heart has four chambers. The two upper chambers are known as the atria, and the two lower chambers are known as the ventricles. The atria contract at the same time. When atria contract, blood is forced into the heart’s lower chambers which are the ventricles. Both ventricles receive blood from their respective atria. For example the left ventricle receives blood only from the left atrium and vice versa. The ventricles then contract simultaneously to pump blood out of the heart. The human heart "beats" (or expands and contracts) to pump blood which carries oxygen and important nutrients to all areas of the body and waste away from the body. How does the Heart work
13. The Purpose of the Aorta It receives the blood from the heart and routes it to all the parts of the body. It is the main artery in the human body. How does the Aorta work The aorta is the main (and largest) artery of the circulatory system. It carries the blood out of the heart from the left ventricle. The heart pushes the blood through the aorta.
14. Leukaemia Leukaemia is cancer that starts in the tissue that forms blood. What is Leukaemia?
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