IGCSE Biology glossary
Heart
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A muscular organ that pumps blood around the body through a double circulatory system. The right side pumps deoxygenated blood to the lungs (pulmonary circulation) and the left side pumps oxygenated blood to the rest of the body (systemic circulation). It has four chambers: two atria and two ventricles.
What to include in an exam answer
Know the four chambers and major blood vessels. The left ventricle has a thicker wall than the right because it pumps blood at higher pressure to the whole body. Blood flows: vena cava to right atrium, right ventricle, pulmonary artery, lungs, pulmonary vein, left atrium, left ventricle, aorta.
Example in context
Explain why the left ventricle wall is thicker than the right ventricle wall (2 marks): The left ventricle pumps blood to the whole body (systemic circulation), which requires higher pressure to push blood through the longer distance. The thicker muscle wall generates this greater force of contraction.
Related syllabus topic
Transport in animals