Human Defence System

Question 1

Ear

Answer 1

Ear wax and hairs trap pathogens

Question 2

Eyes

Answer 2

Tears have antiseptic properties that kill bacteria

Question 3

Nose

Answer 3

Nose hair and mucus traps pathogens

Question 4

Stomach

Answer 4

Contains HCl that kills pathogens

Question 5

Skin

Answer 5

• Scabs form when the skin is broken (blood clotting)
• waterproof
• top layer of skin is dead
• skin forms a barrier

Question 6

Trachea and bronchi

Answer 6

Produce mucus to trap the pathogens, then cilia waft it back through to be swallowed to be killed by stomach

Question 7

Phagocytes

Answer 7

• follow chemical train formed by bacteria
• engulf bacteria
• kill bacteria by digesting them with enzymes

Question 8

Lymphocytes

Answer 8

-detect pathogens

• produce proteins and antibodies which attach to the antigens of the pathogen, killing it
• memory cells are produced so that if infected with same virus, you can kill it quicker

Or

-produce antitoxins which bind to toxins, neutralising them

Question 9

How does your immune system destroy pathogens

Answer 9

It produces white blood cells which are constantly patrolling for microbes to kill. The white blood cells engulf foreign cells and digest them (phagocytosis)