Protecting the Breathing System (Cambridge (CIE) IGCSE Biology)
Revision Note
Written by: Lára Marie McIvor
Reviewed by: Lucy Kirkham
Protecting the Breathing System: Extended
Extended Tier Only
The passages down to the lungs are lined with ciliated epithelial cells
Cilia comes from the Latin for eyelash, so unsurprisingly these cells have tiny hairs on the end of them that beat and push mucus up the passages towards the nose and throat where it can be removed
The mucus is made by special mucus-producing cells called goblet cells because they are shaped like a goblet, or cup
The mucus traps particles, pathogens like bacteria or viruses, and dust and prevents them getting into the lungs and damaging the cells there
Mucus traps particles, dust and pathogens and cilia beat and push it up and away from the lungs
Examiner Tips and Tricks
The function of cilia and mucus is often a 3-mark question on the extended paper.The examiners are looking for you to state the following:
The mucus is produced by goblet cells and traps bacteria, dust, particles
The cilia beat
And push the mucus away from the lungs towards the throat
This is quite simple, but often marks are lost as students haven’t been precise enough with their explanations!
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