GCSE Combined Science (AQA)

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Heart Circulation

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Organisation Animal Tissues, Organs and Organ Systems

Heart Circulation

3:27 Circulatory and Respiratory System
Spec 4.2.2.2
Previous Heart Anatomy Next Controlling Heart Rate
  • The heart is an organ that pumps blood around the body in a double circulatory system.
  • The right and left sides of the heart are reversed in the image for clarity.
  • Blue indicates deoxygenated blood, used for diagrammatic purposes; blood is not actually blue.
  • Red indicates oxygenated blood on the left side of the heart.
  • The circulatory system has two separate circuits, and blood passes through the heart twice.
  • Blood first fills the atria, then moves into the ventricles, and is finally pumped out of the heart.
  • Deoxygenated blood from the body enters the right atrium via the vena cava.
  • Blood is then pumped from the right atrium into the right ventricle.
  • From the right ventricle, blood is pumped through the pulmonary artery to the lungs for gas exchange.
  • Valves in the heart prevent the backflow of blood, ensuring one-way movement.
  • The pulmonary artery is the only artery that carries deoxygenated blood.
  • Oxygenated blood returns to the left atrium of the heart through the pulmonary vein, the only vein that carries oxygenated blood.
  • Blood is then pumped from the left atrium into the left ventricle.
  • Oxygenated blood is pumped from the left ventricle through the aorta to the body's tissues and organs.
  • The left side of the heart has more muscle and a thicker wall to pump blood around the entire body.
  • For exams, it is essential to know the heart structure and the double circulation system, where the right side pumps blood to the lungs and the left side pumps blood to the rest of the body.

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