Immune system (defences against pathogens)

What are the two types of defence systems in the human body

Immune system

Physical and chemical barriers

Example of a physical barrier

The skin

Examples of a chemical barrier

Stomach acid

Function of physical and chemical barriers

Prevent pathogens from entering the body

Function of the immune system

Destroying pathogens which enter the body

3 main functions of white blood cells

Phagocytosis

Production of antibodies

Production of anti toxins

What is the process of phagocytosis

• A white blood cell tracks down a pathogen

• The white blood cell binds to the pathogen

• The phagocyte membrane engulfs the pathogen

• The enzymes inside the phagocyte break down the pathogen in order to destroy it

How do antibodies work

Antibodies are produced to identify pathogens to white blood cells

they lock onto the pathogen and act as a signal for white blood cells to destroy the pathogens

once they bind to a certain type of pathogen they can only bind to that specific pathogen

this means that when the pathogen comes back antibodies are rapidly produced causing immunity