The Four Chambers of the Human Heart: Anatomy and Blood Flow

Chamber Anatomy & Flow

Chamber	Location	Receives	Pumps To	Valve (Outlet)
Right Atrium (RA)	Upper right	Systemic venous blood (SVC, IVC, coronary sinus) — deoxygenated	Right Ventricle	Tricuspid valve
Right Ventricle (RV)	Lower right	RA	Pulmonary artery → Lungs	Pulmonary valve
Left Atrium (LA)	Upper left	Pulmonary venous blood (4 pulmonary veins) — oxygenated	Left Ventricle	Mitral valve
Left Ventricle (LV)	Lower left	LA	Aorta → Systemic circulation	Aortic valve

Key Features

• Septae: Interatrial septum (fossa ovalis), interventricular septum (muscular + membranous).
• Valves: AV valves (tricuspid, mitral) prevent backflow to atria; semilunar valves (pulmonary, aortic) prevent backflow to ventricles.
• Conduction: SA node (RA) → AV node → Bundle of His → bundle branches → Purkinje fibers.
• Coronary supply: RCA (RA, RV, inferior LV), LAD (anterior LV, septum), LCx (lateral LV).

Circulatory Circuits

• Pulmonary circulation: RV → pulmonary artery → lungs → pulmonary veins → LA. Low pressure, high flow.
• Systemic circulation: LV → aorta → body → vena cavae → RA. High pressure, high resistance.

The four-chambered heart ensures complete separation of oxygenated and deoxygenated blood, enabling high-pressure systemic delivery essential for endothermy and complex physiology.