Y9 Biology - heart

Double circulatory system

Humans have two blood circuits: one to the lungs and one to the body

Major heart vessels

Aorta, vena cava, pulmonary artery, pulmonary vein, coronary arteries

Coronary arteries

Supply oxygenated blood to the heart muscle

Vena cava

Takes deoxygenated blood from body to right atrium

Aorta

Pumps oxygenated blood from Legt ventricle to body

Heart valves

Prevent backflow and keep blood moving one way

Pacemaker cells

Cells in the right atrium that control resting heart rate

Artificial pacemaker

Electrical device implanted to correct irregular heart rhythms

Arteries

Thick walls, elastic tissue, small lumen, carry blood at high pressure

Veins

Thin walls, large lumen, valves to prevent backflow at low pressure

Capillaries

One‑cell‑thick walls for fast diffusion and large exchange surface

Blood flow rate

Calculated using rate = volume ÷ time

Left ventricle thickness

Thicker wall because it pumps blood at high pressure to the whole body

Pulmonary artery/vein

Pulmonary artery carries deoxygenated blood, pulmonary vein carries oxygenated blood

Heart oxygen supply

Heart muscle needs oxygen and glucose for aerobic respiration

Blood pressure

Force of blood pushing against artery walls as the heart pumps