1.1 Composition and functions of blood

Composition of Blood

• Red blood cells (40-45%)

• White blood cells (<1%)

• Platelets (<1%)

• Plasma (55%)

White Blood Cells

They are responsible for defense against disease and building immunity.

Leukocytes

Another name for white blood cells

Function of white blood cells

They play a vital role in identifying and removing abnormal cells, including those that could become cancer cells.

Phagocyte

A type of white blood cell

Phagocytosis

A process whereby certain white blood cells engulf and kill invading microorganisms such as bacteria and viruses.

Lymphocytes

A type of white blood cell

Antibodies

Special proteins that certain lymphocytes produce to fight off harmful bacteria and viruses.

The two functions of white blood cells

1. Fighting infections

2. Destroying cancer cells

The two main ways white blood cells fight infection

• Use of antibodies

• The process of phagocytosis

How antibodies work

1. They recognise and attach to specific pathogens

2. They attach to the germ to stop it from functioning properly

3. They mark it for destruction by other immune cells

How do Phagocytosis work

Red blood cells

They carry oxygen to cells

Another name for red blood cells

Erythrocytes