CF & CFTR protein

Question 1

1) Explain the role of the CFTR protein

Answer 1

acts as a channel across membranes of cells that produce mucus, the channel transports chloride ions into and out of cells

Question 2

Explain how a faulty CFTR protein results in thicker, stickier mucus in CF sufferers

Answer 2

-when there’s too little water in the mucus, chloride ions can’t be secreted across the apical membrane
-The epithelial sodium ion channels aren’t blocked and allow more sodium ions than normal into the epithelial cells
-there’s continual sodium absorption from the mucus by the epithelial cells as the epithelial sodium ion channels are always open
-the raised levels of sodium ions in the cells then draw chloride ions and water out of the mucus by osmosis
-This makes the mucus even more sticky

Question 3

3) Explain the effects of CF on the respiratory system (typical 4/5 mark question)

Answer 3

-over inflation of the lungs as the sticky mucus tends to block their bronchioles preventing movement of air into the alveoli beyond the blockage reducing the amount of alveoli providing surface area for gas exchange, these blaockages often allow air to pass when the person breathes in but not when they breathe out -> resulting in over inflation of the lung tissue beyond the blockage
-higher risk of lung infection, low levels of oxygen in the mucus of people with CF because oxygen diffuses slowly through it and harmful bacteria can thrive in these anaerobic conditions

Question 4

4) Explain the effects of CF on the reproductive system, incl. both males and females

Answer 4

-obstruction of sperm canal in men and lack the vas deferens which means sperm cannot leave the testes
-increase in thick mucus plug in cervix which stops sperm from reaching the egg

Question 5

Explain the effects of CF on the digestive system (typical 4/5 mark question)

Answer 5

sticky mucus blocks ducts in the pancreas and prevents enzymes from reaching the small intestine to digest food.