cystic fibrosis

• What causes thicker mucus in CF sufferers (4) 

  -       Gene mutation causes a non-functioning CFTR protein channel 

  -       Chloride ions can thus not move out of epithelial cells

  -       Accumulation of sodium and chloride ions in the cells causes water to osmose out of mucus and into cells+ prevents water moving into mucus.
• Explain why cystic fibrosis affects the rate of oxygen uptake in the lungs (3)

  -       Thick mucus which accumulates and cannot be moved by cilia 

  -       Restricting air flow through bronchi

  -       Reducing surface area for gas exchange in the alveoli 
• Explain why thicker mucus is produced if the functioning of the CFTR channel protein is impaired (2) 

  -       Impaired channel means chloride ions remain in the epithelial cells 

  -       So, no water moves out of cells into mucus via osmosis 
• Explain why these children with CF would be given dietary supplements and digestive enzymes. (5)

  • CF leads to thicker mucus which blocks the pancreatic duct of the pancreas.
  • This means less digestive/pancreatic enzymes can be released into the small intestines thus less food is digested and broken down into nutrients.
  • Therefore, less nutrients are being absorbed into the blood via the small intestines.
  • Thus children do not have the right amino acids or minerals for growth and development and to carry out certain bodily processes, so supplements are taken to increase growth rate. 
•  Describe the role of the CFTR protein in ensuring that the mucus produced in the lungs has the right consistency (3)

  -        These channels allow chloride ions to diffuse out of epithelial cells into mucus, sodium ions leave cells following the calcium ions.

  -        This creates a higher concentration in the mucus than outside 

  -        Therefore, water moves out of cells and into the mucus via osmosis
• People with CF require a higher energy diet. They are also more likely to develop problems in the pancreas. Men with cystic fibrosis are less likely to be able to release sperm. Discuss why a person with cystic fibrosis could have these symptoms (6)

  • A person with cf has thick, sticky mucus which can block the pancreatic duct, therefore fewer digestive enzymes can be released into the small intestines, less food is digested and less nutrients can be absorbed into blood stream from small intestines`
• why are men with CF less able to release sperm

  • . Furthermore, in men the tubes of the testes can become blocked with mucus, preventing sperm reaching penis and less sperm is released.
• why might people with CF develop pancreatic problems

  • This can cause problems in the pancreas as digestive enzymes build up and are not release which can cause damage to pancreatic cells and cysts can form in the pancreas.