1. The Blood
Human Biology

2. What is blood? Blood is the liquid tissue of transport in humans.
It carries oxygen, carbon dioxide, nutrients, cellular wastes, and hormones throughout the body.
Most people have about 6 litres of blood.

3. Six Functions of Blood
Blood transports materials from one place to another.
Blood provides the watery environment for individual cells.
Blood helps to maintain a constant internal body temperature.

4. Six Functions of Blood
Blood plays a major role in combating disease and infection
Blood helps to regulate the body’s pH levels.
Blood prevents the loss of body fluids through the clotting process.

5. Components of Blood Blood is made up of cells floating in a liquid.
The liquid part of blood is called plasma and the cells found in the plasma are red blood cells, white blood cells, and cell fragments called platelets.

6. Plasma
Plasma is a clear straw-colored liquid made up of 90% water and 10% dissolved substances such as proteins, salts, and hormones.
Plasma makes up 55% of your blood.
Plasma carries dissolved food to our body’s cells, and carries wastes away from our cells.

7. Red Blood Cells
Red blood cells are the most numerous of all blood cells and they make up about 44% of your blood.
Their job is to carry oxygen and carbon dioxide.
Hemoglobin is a special protein that makes your blood red when it is carrying oxygen.
They are produced in the bone marrow.

8. White Blood Cells
White blood cells help protect the body against infection by bacteria by making antibodies.
They are produced in the spleen and lymph nodes.

9. Platelets Platelets are small cell fragments
They play an important role in blood clotting.
They use a special protein called fibrin and the mineral calcium to help the blood clot.
They are produced from bone cells in the marrow.