very acidic ph - stomach
mucociliary escalator - intestines
cerumen and sebum - ear
lysozyme - tears and saliva
keratin and tightly packed cells - skin
The correct answer is "mucociliary escalator intestines".
The mucociliary escalator is a mechanism that belongs to the bronchi, not the intestines. The mucociliary escalator is a mechanism of self-clearing where cilium, cilia and mucus work together to expel any material that's solid, or not too fluid or gaseous, including pathogens. From the main bronchi to the alveoli there is a moist lining produced by the specific present epithelium. This epithelium presents cilia. The cilia are embedded in mucus. The mucus is what helps in trapping any material that's solid, or not too fluid or gaseous, including pathogens. After these are trapped so that they don't progress to the alveoli, the cilia move in such a way that push the particles again to the exterior of the bronchi, like an escalator.
