Fighting disease

Question 1

Physical Barriers:

Answer 1

The skin blocks pathogen entry, while blood clots seal wounds. Nose hairs and mucus trap airborne pathogens, and cilia sweep mucus from airways to the throat.

Question 2

Chemical Barriers:

Answer 2

Stomach acid (hydrochloric acid) kills swallowed pathogens, and lysozyme in tears destroys bacteria.

Question 3

Immune Response:

Answer 3

If pathogens bypass these defences, white blood cells take action. B-lymphocytes, a type of white blood cell, detect antigens (unique molecules on pathogens) and produce antibodies, which bind to and help destroy the invaders.

Question 4

Memory Cells:

Answer 4

After an immune response, memory lymphocytes remain in the body, enabling quicker and stronger defence against future infections by the same pathogen.

Question 5

HIV & Its Impact:

Answer 5

HIV attacks white blood cells, weakening immunity and making infections harder to fight.