How do the trachea and bronchi help prevent infection?

How do the trachea and bronchi help prevent infection?

• A. They produce anti-toxins
• B. They filter pathogens with bone structures
• C. Mucus in our airways traps pathogens, and ciliated cells waft this up to our throat to be expelled or swallowed.
• D. They form a barrier to pathogens trying to enter our body

Answer: (C)

Protecting the lower airways mainly relies on mucociliary clearance. The trachea and bronchi are lined with goblet cells that produce mucus and with ciliated epithelial cells. The mucus traps inhaled pathogens and particles, and the cilia beat in coordinated waves to move this mucus upward toward the throat. From there you can either cough it out or swallow it, and swallowed mucus is exposed to stomach acid and enzymes that help destroy the invaders. This active clearing rapidly removes potential infections before they reach deeper parts of the lungs. Other options don’t fit as well because these airways don’t produce anti-toxins, there aren’t bone structures filtering pathogens there, and while the airway lining acts as a barrier, the key protective mechanism described here is the mucus plus the ciliary movement that clears pathogens.

Protecting the lower airways mainly relies on mucociliary clearance. The trachea and bronchi are lined with goblet cells that produce mucus and with ciliated epithelial cells. The mucus traps inhaled pathogens and particles, and the cilia beat in coordinated waves to move this mucus upward toward the throat. From there you can either cough it out or swallow it, and swallowed mucus is exposed to stomach acid and enzymes that help destroy the invaders. This active clearing rapidly removes potential infections before they reach deeper parts of the lungs.

Other options don’t fit as well because these airways don’t produce anti-toxins, there aren’t bone structures filtering pathogens there, and while the airway lining acts as a barrier, the key protective mechanism described here is the mucus plus the ciliary movement that clears pathogens.