The mammalian heart uses four chambers, valves, thick ventricular muscle and named vessels to pump blood one way through pulmonary and systemic circuits.
Coverage 2012–2024 · Updated 15 Jul 2026
The mammalian heart is a myogenic, four-chambered double pump adapted to deliver pressurized blood unidirectionally to pulmonary and systemic arteries.
Atria receive blood; ventricles eject it. The septum separates oxygenated and deoxygenated sides, the thicker left ventricular cardiac muscle generates systemic pressure, and coronary vessels supply the metabolically active myocardium.
The sinoatrial pacemaker initiates each beat. Atrioventricular valves prevent return to atria, semilunar valves prevent return from arteries, and tendinous cords stop AV valves inverting under ventricular pressure.
Trace flow: venae cavae → right atrium → tricuspid valve → right ventricle → pulmonary semilunar valve/artery → lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aortic semilunar valve/aorta.
Valves open and close because of pressure differences; they do not actively pull blood. The right side pumps deoxygenated blood to lungs, while the left side pumps oxygenated blood to the body.
This objective is assessed through structured response, commonly using Identify / State / Label.
Identify / State / Label / Describe / Explain / Draw
Build the answer around this relationship: Atria receive blood from veins and pass it into ventricles.
Connecting pulmonary vessels to the wrong chambers in heart pathway questions.
Representative question
Draw a labelled diagram of the human heart showing the attached blood vessels.
HL transport adds pressure and route systems. Tissue fluid forms by capillary pressure and returns by osmotic pull or lymph. Double circulation separates pulmonary and systemic routes. The heart creates directional pressure with chambers, septum, valves, and cycle timing. Plants add root pressure and phloem pressure-flow translocation.
