2. How cystic fibrosis affects the lungs Symptoms: Severe coughing - to remove excess mucus. Breathlessness - shortage of oxygen increases tiredness and lack of energy Infections - as bacteria are trapped in mucus Sticky mucus builds up in the airways, reducing flow of air into alveoli. Lungs gradually fill up with mucus, making them less effective for gas exchange.

3. How does cystic fibrosis affect the reproductive systems? MenWomen Sperm duct is blocked and prevents movement of sperm During the menstrual cycle the levels of mucus vary. Can lack the sperm ducts Women with CF have thick levels of mucus which can block the cervix so sperm cannot reach them.

4. How cystic fibrosis affects the digestive system: Thick, sticky mucus blocks the pancreatic duct preventing enzymes from reaching the duodenum. Food is not digested and absorbed sufferers fail to put on body mass and suffer malnutrition. Trapped digestive enzymes damage the pancreatic cells affecting cells producing insulin resulting in diabetes.

5. What does the CFTR protein do? It helps control the viscosity (or stickiness) of mucus that lines the epithelial cells of the airways, digestive and reproductive systems too runny: the mucus can flood the airways mucus cilia epithelial cell If the mucus in airways is… too sticky: the cilia cannot beat and remove the mucus, which then clogs up airways

6. When there is excess water in the mucus mucus tissue fluid CFTR channel closed Na + channel open pump Na + H2OH2O H2OH2O Cl - apical membrane basal membrane 1 2 3 4 5 Water is drawn out of the mucus and it thickens Cl - H2OH2O

7. When there is too little water in the mucus mucus tissue fluid CFTR channel open Na + channel closed Na + H2OH2O H2OH2O Cl - apical membrane basal membrane Cl - 1 2 3 4 5 Water is drawn out of the mucus and it becomes less sticky Na + H2OH2O The CFTR somehow blocks the sodium channels pump

8. With cystic fibrosis mucus tissue fluid CFTR non- functional Na + channel open Na + H2OH2O H2OH2O Cl - apical membrane basal membrane X Water drawn out by osmosis 1 23 The mucus becomes very thick and sticky Cl - H2OH2O The CFTR protein cannot block the sodium channels so they are always open

9. Check your answers!

10. 1. Na + is actively pumped across the basal membrane (bottom part). 2. Na + diffuses through sodium channels in apical membrane (top part). 3. Cl - diffuses down electrical gradient (basal end of cell becomes more positively charged due to Na + ). 4. Water is drawn out of cells by osmosis due to high salt concentration in tissue fluid (basal end). 5. Water is drawn out of mucus by osmosis.

11. 1.Cl - is pumped into the cell. 2.The CFTR channel is open so Cl - ions diffuse through to the mucus. 3.Na + then diffuses down the electrical gradient (area of negative charge) into the mucus. 4.There is a high concentration of salt in the mucus so water leaves the cell and enters the mucus by osmosis. 5.Water from the basal end of the cell is drawn into the cell by osmosis.

12. Use your knowledge of functioning CFTR proteins to explain why CF patients cannot control their mucus fluidity mucus tissue fluid CFTR non- functional Na + channel open Na + H2OH2O H2OH2O Cl - apical membrane basal membrane X Water drawn out by osmosis 1 23 Cl - H2OH2O The CFTR protein cannot block the sodium channels so they are always open