blood

• Blood contains plasma, red blood cells, white blood cells and platelets
• Plasma is the liquid part of blood that carries nutrients to tissues and removes waste products from them.
• Red blood cells contain haemoglobin which binds with oxygen molecules and transports it around the body.
• White blood cells are involved in fighting infection by engulfing pathogens (phagocytosis)
• Platelets clump together at sites of damage to form a plug to stop bleeding
• The heart pumps blood round the circulatory system
• Arteries carry blood away from the heart under high pressure
• The heart pumps blood round the circulatory system through arteries, capillaries and veins
• Capillaries allow exchange between blood and tissues
• Veins return blood back to the heart under low pressure
• Blood is pumped around the body by the heart