B3 - Non Specific Defence Systems

What are the two main defense systems in the human body against pathogens?

The nonspecific defense system and the immune system.

What is the role of the nonspecific defense system?

To prevent pathogens from entering the human body.

Name the four main parts of the nonspecific defense system.

Skin, nose, trachea and bronchi (cilia and mucus), and stomach acid.

How does the skin protect the body from pathogens?

It forms a protective layer made of dead cells that is difficult for pathogens to penetrate.

What oily substance does the skin produce and what is its function?

Sebum, which can kill bacteria.

What happens if the skin is damaged?

Pathogens can enter the body, but the skin scabs over to prevent this.

Why are the nostrils and mouth vulnerable to pathogens?

Because they are openings not covered by skin.

How does the nose help prevent pathogens from entering the body?

It contains hairs and mucus that trap pathogens.

What are cilia and where are they found?

Tiny hairs found in the trachea and bronchi.

How do cilia help defend against pathogens?

They are covered in mucus which traps pathogens and they move the mucus upwards towards the throat.

What happens to the mucus that cilia move towards the throat?

It is swallowed into the stomach.

How does the stomach protect the body from pathogens?

It contains hydrochloric acid which kills pathogens.

Why can pathogens still sometimes cause disease despite the nonspecific defense system?

Because these defenses are not 100% effective and some pathogens can get through.

What is the next line of defense after the nonspecific defense system?

The immune system.

Why is sebum important in the nonspecific defense system?

Because it kills bacteria on the skin surface.

What is the function of mucus in the respiratory tract?

To trap pathogens and prevent them from reaching the lungs.

What is the purpose of scabbing when skin is damaged?

To prevent pathogens from entering the body.

What is the difference between the nonspecific defense system and the immune system?

The nonspecific defense system prevents pathogens from entering; the immune system attacks pathogens that enter.