In cystic fibrosis, chloride transport is abnormal, leading to chloride ions being trapped inside cells. Which statement is correct?

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Multiple Choice

In cystic fibrosis, chloride transport is abnormal, leading to chloride ions being trapped inside cells. Which statement is correct?

In cystic fibrosis, the defect in the CFTR chloride channel means chloride cannot move from the inside of epithelial cells into the airway lumen. This failure to secrete chloride into the lumen reduces water movement into the mucus by osmosis, so the mucus becomes thick and dehydrated. Saying chloride is trapped inside cells captures the essence: the normal route of chloride into the surface lining is blocked, so chloride stays intracellular rather than being secreted into the lumen. The other ideas imply chloride is being moved into the mucus, into the bloodstream, or excreted into the lumen, which would require chloride to cross the epithelial boundary into compartments that CFTR dysfunction prevents in this context.

In cystic fibrosis, the defect in the CFTR chloride channel means chloride cannot move from the inside of epithelial cells into the airway lumen. This failure to secrete chloride into the lumen reduces water movement into the mucus by osmosis, so the mucus becomes thick and dehydrated. Saying chloride is trapped inside cells captures the essence: the normal route of chloride into the surface lining is blocked, so chloride stays intracellular rather than being secreted into the lumen.

The other ideas imply chloride is being moved into the mucus, into the bloodstream, or excreted into the lumen, which would require chloride to cross the epithelial boundary into compartments that CFTR dysfunction prevents in this context.

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