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B3: Transporting Dissolved Materials
Substances are transported
around the body by the
circulation system (the heart,
the blood vessels and the
They are transported from
where they are taken into the
body to the cells, or from the
cells to where they are
removed from the body.
The heart pumps blood around
the body. Blood flows from the
heart to the organs through
arteries and returns through
In the organs, blood flows through capillaries.
Substances needed by cells in the body tissues pass out of the
blood, and substances produced by the cells pass into the blood
through the walls of the capillaries.
There are two separate circulation systems, one to the lungs and
one to all the other organs of the body.
Blood plasma transports:
carbon dioxide from the organs to the lungs
soluble products of digestion from the small intestine to
urea from the liver to the kidneys.
Red Blood Cells
Red blood cells transport oxygen from the lungs to the organs.
Red blood cells have no nucleus.
They are packed with a red pigment called haemoglobin.