Diseases and Immunity: Question 6
Syllabus 10.1
A dust storm blows across a farm. James, a farm worker, spends the afternoon outdoors, breathing in air that is thick with dust, some of which carries fungal spores that could cause a lung infection if they reach his airways.
Which statement correctly describes how James's nose and airways help to protect him from these spores?
Show worked solution Hide worked solution
Worked solution
Step 1: Recall the body’s defences against inhaled pathogens
Before a pathogen has even entered the body’s tissues, several barrier defences can stop it getting that far. Two of these act specifically on air breathed in through the nose and airways: the hairs in the nose, and the mucus that lines the airways. Together, these trap dust and pathogens carried in the air, stopping many of them from travelling further into the lungs.
Step 2: Apply this to James’s situation
As James breathes in dust-laden air, the hairs in his nose catch some of the larger particles, and the mucus lining his nose and airways traps many of the smaller particles and spores that get past the hairs. This happens before any spore has reached deeper into his airways or entered his body’s tissues.
Step 3: Rule out the other options
- B: white blood cells defend against pathogens that have already entered the body’s tissues, not pathogens still in the nose or airways.
- C: stomach acid is a defence against pathogens that are swallowed, not ones that are breathed in; it is not produced in the nose.
- D: the lining of the nose and airways is not skin, and it does not work by absorbing spores; it works by trapping them in mucus.
Final answer
- The hairs in the nose and the mucus lining the airways trap many of the spores before they travel further, option A.