Cystic Fibrosis

Question 1

What is CF?

Answer 1

An inherited disorder that mainly affects the respiratory, digestive and reproductive systems.

Question 2

What causes CF?

Answer 2

• A recessive allele (homozygous for allele ff to suffer)

- Mutation in gene that codes for CFTR protein.

Question 3

Explain the function of the CFTR protein.

Answer 3

It transports chloride ions out of cells into mucus, causing water to move into the mucus by osmosis.

Question 4

Explain what happens to the CFTR protein in a CF sufferer.

Answer 4

It is less efficient at transporting chloride ions out of the cell so less water moves out by osmosis. This makes people with CF abnormally thick and sticky.

Question 5

How does the CF affect the respiratory system?

Answer 5

• Cilia are unable to move mucus towards throat because it is thick and sticky, mucus builds in the airways
• Some airways can become completely blocked by mucus- gas exchange can’t take place in area of blockage
• Surface area for gas exchange is reduced, causing breathing difficulties
• Lung infections can occur more often as micro-organisms can breed and not be removed from mucus

Question 6

State some treatments for CF.

Answer 6

• Antibiotics to kill the bacteria trapped in mucus
• Physiotherapy to help dislodge mucus and improve gas exchange.
• Lung transplants to replace affected lungs

Question 7

How does CF affect the digestive system?

Answer 7

• Tube connecting pancreas to small intestine can be blocked with mucus.
• Digestive enzymes, produced in pancreas, cannot enter small intestine, reducing ability to digest food and absorb nutrients.
• Cysts in pancreas caused by digestive enzymes digesting pancreatic cells- formation of cysts inhibits production of enzymes, reducing ability to digest food and absorb nutrients.
• Mucus lining the small intestine is abnormally thick- inhibits the absorption of nutrients

Question 8

How does the CF affect the reproductive system?

Answer 8

• Sperm cannot reach penis because tubes connecting testicles to penis are absent or are blocked
• Cervical mucus prevents sperm from reaching the egg- thick mucus reduces mobility of the sperm, reducing its chances of reaching the egg.