Blood

• Contains Haemogobin.
• Do not have a nucleus
• Disc shape

Increases the surface area which inreases oxygen absorption.

• Thin membrane

Allows oxygen to diffuse easily in and out of the cell.

• They have a nucleus
• They have a cytoplasm

That has flowing movement, helps them sqeeze through cells in the blood capillary walls into tissues where they are able to engulf bacteria and viruses.

• Secrete digestive enzymes

Which destroys the bacteria and viruses.

• Small fragments of cells
• They do not have a nucleus
• They contain proteins

That enable them to stick to breaks in the blood vessel wall and also stick to each other.

A clot forms that stops the bleeding