Composition of the Blood

Composition of the blood: plasma, red blood cells, white blood cells, platelets

Plasma transports:

• Carbon dioxide
• Digested food
• Urea
• Hormones
• Distributes heat energy around the body
• Components of the blood

Red blood cells

Red blood cells transport %%oxygen%% from the lungs to respiring tissue

Adaptations:

• %%Biconcave shape%% to give a large SA:VOL ratio for efficient absorption of oxygen
• Large amounts of %%haemoglobin%%, for oxygen transportation (binds to O2 for transportation to respiring cells)
• No nucleus to %%maximise space%% for haemoglobin, so more oxygen can be transported

White blood cells

White blood cells fight %%infection%%

• Larger than red blood cells, so it can engulf pathogens
• Has a %%nucleus%% so it can divide
• Has a nucleus so it can produce %%antibodies%%

Platelets

Platelets are fragments of cells, which help to repair tissues and close wounds externally and internally

• When the skin is cut, platelets produce a %%network of fibres%%, stopping the cells from flowing out and forming a blood clot
• The clot turns into a %%scab,%% which stops bacteria from getting to the wound.