What is the normal function of that affected in cystic fibrosis?

The normal function affected in cystic fibrosis is the regulation of the transport of chloride and sodium ions across epithelial cell membranes. Cystic fibrosis is an autosomal recessive genetic disorder caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene.

Here's a detailed explanation of the normal function:

1. Chloride transport: CFTR acts as a chloride channel, allowing chloride ions (Cl-) to pass through the epithelial cell membranes. This process is crucial for maintaining the proper balance of ions and fluid in various organs, including the lungs, pancreas, intestines, and sweat glands.

2. Sodium transport: The movement of chloride ions through CFTR channels creates an electrical gradient that influences the movement of sodium ions (Na+). This coordinated transport of chloride and sodium ions is essential for regulating the movement of water across epithelial cell layers.

3. Hydration of mucus: In the lungs, CFTR-mediated chloride and sodium transport helps maintain a layer of thin, watery mucus that lines the airways. This mucus layer functions as a protective barrier, trapping bacteria and particles to prevent infections.

4. Pancreatic function: In the pancreas, CFTR is involved in the secretion of bicarbonate ions (HCO3-), which helps neutralize the acidic environment of the pancreatic juice. This is important for the proper digestion and absorption of nutrients.

5. Sweat gland function: CFTR also plays a role in regulating sweat production. When the body sweats, CFTR channels allow chloride and sodium ions to be secreted into the sweat, contributing to the salt content of sweat.

In individuals with cystic fibrosis, mutations in the CFTR gene disrupt these normal functions, leading to impaired chloride and sodium transport across epithelial cell membranes. This results in the production of thick, sticky mucus, increased sweat salt concentration, and other symptoms characteristic of the disease.