Why can't CF lungs regulate the water content
- In a person who has CF, the CFTR protein may be missing or not function.
- If there is too little water in the mucus, Cl- cannot be secreted across the apical membrane and there is no blockage of the epithelial sodium ion channels.
- Since the Na+ channels are always open, there is continual Na+ absorption by the epithelial cells.
- The raised levels of Na+ draw chloride ions and water out of the mucus into the cells
- This makes the mucus more viscous
- Which makes it harder for the beating cilia to move it.
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