A client with cystic fibrosis (CF) is concerned about how this condition affects their body.
The client asks, “Why does CF lead to the production of thick mucus in the lungs and other organs?” Which of the following responses by the nurse is accurate?
A.
“The CFTR gene mutation causes excessive water transport in the body.”
B.
“CF results in an overproduction of a specific enzyme that thickens mucus.”
C.
“The CFTR gene mutation impairs chloride and water transport in cells.”
D.
“CF primarily affects the production of surfactant in the lungs.”
The Correct answer and Explanation is:
The correct answer is C: “The CFTR gene mutation impairs chloride and water transport in cells.”
Explanation
Cystic fibrosis (CF) is a genetic disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes a protein responsible for transporting chloride ions across epithelial cell membranes. In healthy individuals, CFTR helps maintain the balance of salt and water on the surfaces of various tissues, including the lungs and pancreas. However, in CF patients, mutations in the CFTR gene lead to defective or absent CFTR proteins. This disruption primarily affects chloride and bicarbonate ion transport.
Due to the impaired transport of chloride ions, there is a resultant reduction in the secretion of water into the airway surface liquid. This creates an environment where mucus becomes thick and sticky. The normal balance of water in mucus is essential for it to remain thin and easily cleared by ciliary action in the respiratory tract. When mucus thickens, it can obstruct airways, leading to difficulty breathing and increased risk of lung infections due to the trapping of pathogens.
The other options provided do not accurately represent the pathophysiology of cystic fibrosis:
- A is incorrect because the CFTR mutation leads to inadequate, not excessive, water transport.
- B inaccurately suggests that an overproduction of a specific enzyme causes thick mucus; CF is not primarily about enzyme overproduction but rather ion transport impairment.
- D is misleading as CF does not primarily affect surfactant production; surfactant relates to reducing surface tension in the lungs, whereas CF is focused on ion and fluid transport issues.
Understanding the mechanism of CF can help patients manage symptoms better and appreciate the importance of therapies aimed at enhancing mucus clearance and lung function.