Blood Components and Vessels

• Transports blood cells and other substances around your body like carbon dioxide, urea, products of digestion and hormones and enzymes

They carry oxygen to the cells for aerobic respiration

Adaptations

• Biconcave disk-larger SA to V ratio
• Packed with red haemoglobin that reacts with oxygen to make oxyhaemoglobin
• No nucleus to allow for more haemoglobin

• Protect us from infection
• There's less of them and they're bigger

• Made from small fragments of cells
• Help the blood to clot at a wound to form scars

Fibrin is a mesh that catches the platelets

Enzyme controlled reactions where fibrinogen is converted to fibrin

• this net of protein captures red blood cells and platelets forming the clot stopping you from bleeding to death
• The clot dries, forms a scab and then new skin grown, stopping bacteria entering the wound

• Carry blood away from the heart
• Thick walls made from muscle and elastic fibres
• High pressure

• Carry blood towards the heart
• Thin walls and valves protect backflow
• Low pressure

• Allows substances needed by the cells out of the blood
• Narrow, thin-walled blood vessels