Priority 1: Heart structure and blood flow

Know the four chambers, the valves, and the path of blood: vena cava → right atrium → tricuspid valve → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → bicuspid valve → left ventricle → aorta → body. The left ventricle has a thicker wall because it pumps blood to the whole body at higher pressure.

Priority 2: Blood vessels

Compare arteries, veins, and capillaries: wall thickness, lumen size, valves, blood pressure, and function. Link each structural feature to its function.

Priority 3: Blood components

Red blood cells: contain haemoglobin, no nucleus, biconcave: carry oxygen.
White blood cells: phagocytes (engulf pathogens) and lymphocytes (produce antibodies).
Platelets: cell fragments, involved in blood clotting.
Plasma: liquid, transports dissolved substances (glucose, urea, CO₂, hormones).