Question

Explain how the defect in the CFTR ion channel results in the disease. Think about osmosis and how this process is important in maintaining the proper water balance in cells

Answer 1

Ans : CFTR ( Cystic Fibrosis Transmembrane Receptor) is an ion channel protein found on the cells that make the inner lining of lungs. It is pecialized in the transport of chloride ion from inside the cell to outside of the cell. This fuction is very important to maintain the water content on the inner lining of lungs as the chloride ions that come out of the cell through CFTR protein increase the solute concentration outside the cell. Therefore, water from inside the cell moves outside by osmosis i.e. from a region of lower concentration to a region of higher concentration. Thus, this chloride movement helps in the hydration of the inner lining of the lungs. The water content helps in the proper back and forth movement of the hair like structures called villi, which facilitates the pushing up of excessive mucus from within the lungs to the upper thorax for expulsion.

When there is a defect in the CFTR function or an absence of it, there is no movement of chloride ions out of the cells and water content in the lungs in not maintained. The excessive mucus remains inside the lungs and often solidifies due to lack of enough moisture. This leads to cistic fibrosis.

CFTR channel protein is also vital for maintaining the water balance in cells. Water can be expelled out of the cell through invoking osmosis by altering the solute concentration outside the cell.