A. Red Blood Cells

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View of red blood cell under the light microscope (400x) magnification

Function: Red blood cells transport oxygen gas from lungs to other parts of the body.

Red blood cells contain a red pigment known as haemoglobin. Haemoglobin combines reversibly with oxygen gas to form oxyhaemoglobin.

What does reversibly mean?

When there is a high oxygen concentration, haemoglobin combines with oxygen to form oxyhaemoglobin.

At the tissues of the body where there is low oxygen concentration, oxyhaemoglobin dissociates and oxygen is released where it enters the tissues for respiration to occur.

Key Features

(a) No nucleus --> allow more haemoglobin to be packed into

red blood cells where more oxygen gas can be transported.

(b) Biconcave in shape --> increases surface area:volume ratio for faster uptake and release of oxygen gas.

(c) Flexible --> able to squeeze out of capillaries easily.

(d) Contains haemoglobin --> red pigment which combines reversibly with oxygen gas.