Blood contains:
- Plasma.
- Blood cells.
Plasma
Plasma is the liquid part of the blood.
Functions of plasma:
- Transports nutrients, chemicals, wastes, carbon dioxide and heat around the body.
- Contains special proteins that can clot blood to prevent blood loss.
Blood Cells
There are 3 types of blood cells:
- Red blood cells.
- White blood cells.
- Platelets.
Red Blood Cells
- Disc shaped with a hollow or dip in the middle.
- They can bend to fit through blood vessels.
- They have no nucleus.
- They are made in the bone marrow of long bones, for example femur.
- They contain a chemical called haemoglobin.
- Haemoglobin bonds to oxygen in the lungs.
- Functions of Red Blood Cells: to carry oxygen from the lungs to all the cells in the body.
White Blood Cells
- Less numerous than red blood cells.
- Function: to defend the body against disease.
- Some engulf invaders and some produce chemicals called antibodies.
- Antibodies stick to germs, leading to their destruction.
Platelets
- Small fragments of cells.
- Function: help to clot the blood or block small leaks in blood vessels to stop the bleeding.