A Closer Look at Glands: Effects of Defective Channels
A Closer Look at Glands: 
The disease cystic fibrosis has no simple cure in part because no simple case of symptoms exists. The genetic defect directly affects the function of the chloride channel, but this channel is present in multiple body systems. Here we will explain the nature of this defect in sweat glands, and how a similar process fatally affects the pancreas and lungs as well.
For centuries, it has been known that those afflicted with the disease have salty-tasting skin. Even though scientists have extensively studied and understood how the body systems are harmed, this outward manifestation remains the most practical means of diagnosis. A "sweat test" easily determines whether or not a person has cystic fibrosis. A chloride concentration of 40 mM/L indicates a salt content far higher than that of a healthy individual. What could cause the body to lose so much salt?
In a sweat gland, sodium and chloride ions travel freely into the gland from the bloodstream. Water moves into the gland to minimize the gradient of sodium and chloride ions built up inside. Ideally (as in the case of a normal gland), the sodium and chloride ions leave the gland through separate channels back to the bloodstream, where they are reabsorbed. Water is excreted onto the skin surface as sweat. Cystic fibrosis, however, cripples this process. The CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) has formed defectively - it may be shaped irregularly, prohibiting normal activity, or may be entirely excluded from the membrane. Sodium and chloride ions still enter the glands and the water follows, but the CFTR cannot provide transport for the chloride ions to go back through the gland's membrane. The sodium channel is operational, but the charged ions keep an equilibrium in the gland; therefore, sodium is retained with the chloride in the gland. The body loses high levels of salt as an unnatural amount is deposited onto the skin with the water, in the form of sweat.
The effects of faulty CFTR channels are manifested in the airways and pancreas as well. Faulty CFTR channels in the lungs and airways influence airway surface fluids leading to development of a thick, sticky mucus These sticky secretions plug airways and collect heavily on the lung walls, thus providing a prime environment for infection to occur. These fatal infections cannot be fought off, thus leading to chronic lung disease. At the same time, the mucus disrupts the exocrine function of the pancreas and prevents essential food-processing enzymes from reaching the intestines.
An Unhappy EndingCystic fibrosis patients most commonly die of lung disease, the ultimate result of cells lacking an essential protein that would normally allow transport of chloride ions. Various symptoms can be treated, but the disease painfully persists.