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. Even though scientists have extensively studied and understood how the body systems are harmed, this outward manifestation remains the most practical means of diagnosis. 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.
Water is excreted onto the skin surface as sweat. Cystic fibrosis, however, cripples this process. 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 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.