Circulatory SystemEdexcel GCSE Biology: Revision notes
Section 1
Structure of the Heart
Double pump: pulmonary circuit (lungs) and systemic circuit (body). Four chambers: two atria, two ventricles.
Key termsatriaventriclespulmonary circuitsystemic circuit
Section 2
Chamber Wall Thickness
Left ventricle thickest — pumps blood around whole body at high pressure. Right ventricle thinner — only pumps to nearby lungs.
Key termsleft ventricleright ventricle
Section 3
Valves
Atrioventricular valves (between atria/ventricles) and semilunar valves (at aorta/pulmonary artery base) prevent backflow.
Key termsatrioventricular valvessemilunar valves
Section 4
Major Blood Vessels
Aorta: left ventricle→body. Vena cava: body→right atrium. Pulmonary artery: carries deoxygenated blood (unusual). Pulmonary vein: carries oxygenated blood (unusual). Coronary arteries: supply heart muscle.
Key termsaortavena cavacoronary arteries
Section 5
Cardiac Output Calculations
Cardiac output = stroke volume × heart rate.
Key termsheart ratestroke volumecardiac output
Example
SV=70cm³, HR=72: CO=70×72=5040cm³/min.
Must Know
- Heart: double pump, 4 chambers.
- Left ventricle thicker (body pressure) vs right (lungs).
- Valves prevent backflow.
- Aorta=oxygenated out; vena cava=deoxygenated in; pulmonary artery/vein reversed.
- Cardiac output = stroke volume × heart rate.
That's the notes covered.
Carry on to the next subtopic.