Key Organs of the Circulatory System: Heart, Blood Vessels, Lungs, Liver, Kidneys

Heart

• Pumps oxygenated blood to body; returns deoxygenated blood.
• Four chambers: 2 atria (receive), 2 ventricles (pump).

Blood Vessels

• Arteries: Carry oxygenated blood from heart.
• Capillaries: Exchange O₂/CO₂ with tissues.
• Veins: Return deoxygenated blood to heart.

Lungs

• Gas exchange: O₂ in, CO₂ out.
• Alveoli = site of exchange.

Liver

• Detoxifies blood, stores glycogen, produces bile.
• Produces clotting proteins.

Kidneys

• Filter blood, remove waste.
• Regulate BP, produce erythropoietin (stimulates RBC production).