05. The Immune System

What 2 lines of defence does the immune system provide against pathogens?

Preventing entry of pathogens into body, killing pathogens that get into the body

How does the skin prevent the entry of pathogens?

Skin flora make it difficult for pathogens to become established, when the skin is broken blood clots forming a scab sealing the gap

What is skin flora?

Community of microorganisms that live naturally on the skin

What body parts prevent infections?

Eyes, Nose, Trachea and bronchi, Stomach

How do eyes prevent infection?

Produces tears which contain enzymes -> chemical barrier

How does the nose prevent infection?

Has internal hairs -> physical barrier, Cell in nose produce mucus

How does the cells in nose that produce mucus prevent infection?

Trap pathogens before they enter lungs

How do the trachea and bronchi prevent infection? (Not Goblet)

Ciliated cells waft cilia and move mucus and pathogens up to throat where swallowed

How do the trachea and bronchi prevent infection? (Not Ciliated)

Goblet cells create mucus to trap pathogens -> physical barrier

How does the stomach prevent infection?

Hydrochloric acid kills pathogens from mucus, food or water -> chemical barrier

What causes an infection?

When pathogens pass through the non-specific first line of defence

What are the two types of white blood cells?

Phagocytes and lymphocytes

What do phagocytes do?

Ingest and digest microorganisms, attacks any foreign cell

Why do phagocytes ingest and digest?

They’re attracted to pathogens and bind to them

What do phagocytes do after binding to pathogens?

The cell membrane surrounds the pathogen and engulfs it

What happens after phagocytes’ cell membrane surrounds the pathogen?

Enzymes inside the cell break down the pathogen and destroy it

What do lymphocytes do?

Recognise foreign antigens on surface of pathogens -> produce specific antibody + antitoxin for particular pathogens