Blood
Science: KS3, topic 1.6.30
The Blood
The blood delivers oxygen and removes carbon dioxide as it moves around the body. Blood is contains plasma, platelets, red blood cells, and white blood cells.
Blood plasma
- Blood plasma
- Plasma is the straw-coloured liquid component of blood.
- Plasma contains a variety of substances including:
- Suspended nutrients
- Antibodies
- Proteins
- Hormones
- Urea
- Blood cells
Blood platelets
- Blood platelets are found in the blood plasma.
- Platelets are used in blood clotting.
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Red blood cells
- Red blood cells are also called erythrocytes.
- Red blood cells are made in the bone marrow.
- Red blood cells contain a protein called haemoglobin which carries oxygen around the body.
- Red blood cells have a biconcave disc shape and do not have a nucleus.
- This shape increases surface area to maximise oxygen absorption.
- Red blood cells are very thin to make diffusion more efficient.
White blood cells
- White blood cells are part of the body's immune system.
- White blood cells engulf and destroy microorganisms that invade the body.
Test yourself on Blood
What does blood plasma contain?
Select the correct statement in each pair.
A person has fewer red blood cells than normal. What happens to the amount of oxygen their blood can carry?