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Blood and the immune response
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Blood is a tissue made of plasma and cells. It transports substances and defends the body against pathogens.
What blood is made of
Plasma: the liquid part. It transports carbon dioxide, digested food (such as glucose and amino acids), urea, hormones and heat energy.
Red blood cells: carry oxygen.
White blood cells: defend against pathogens.
Platelets: cell fragments involved in blood clotting.
Red blood cells: carry oxygen.
White blood cells: defend against pathogens.
Platelets: cell fragments involved in blood clotting.
Red blood cells
Haemoglobin combines with oxygen in the lungs to form oxyhaemoglobin, then releases it in the tissues.
Adaptations: biconcave disc shape gives a large surface area for oxygen to diffuse in and out; no nucleus leaves more room for haemoglobin; small and flexible to squeeze through capillaries.
Adaptations: biconcave disc shape gives a large surface area for oxygen to diffuse in and out; no nucleus leaves more room for haemoglobin; small and flexible to squeeze through capillaries.
White blood cells
Phagocytes ingest (engulf) pathogens and digest them. This is phagocytosis.
Lymphocytes release antibodies. Each antibody is specific: it only fits the antigens on one type of pathogen.
Antibodies stick pathogens together or mark them so phagocytes can destroy them.
Lymphocytes release antibodies. Each antibody is specific: it only fits the antigens on one type of pathogen.
Antibodies stick pathogens together or mark them so phagocytes can destroy them.
Give two ways a red blood cell is adapted to carry oxygen.
- Its biconcave shape gives a large surface area for diffusion.
- It has no nucleus, so it can hold more haemoglobin.
Answer: Biconcave shape (large surface area) and no nucleus (more haemoglobin).
Plasma carries carbon dioxide, digested food, urea, hormones and heat. Red blood cells are biconcave with no nucleus and are full of haemoglobin. Phagocytes ingest pathogens. Lymphocytes release antibodies specific to a pathogen.
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