Cystic Fibrosis

Question 1

What glands are affected in cystic fibrosis?

Answer 1

The exocrine glands, can be any exocrine glands anywhere in the body

Question 2

Cystic fibrosis is a site specific problem. Explain what this means:

Answer 2

This means that one area in the body may experience excessive secretion, while another experiences the opposite

Question 3

What is the etiology of cystic fibrosis?

Answer 3

• Genetic
• Gene mutation of the CFTR
• Monogenic
• Autosomal recessive

Question 4

What is the CFTR gene? What chromosome is it located on? What does it code for?

Answer 4

The cystic fibrosis transmembrane regulator gene on chr 7, codes for Cl channels on epithelium.

Question 5

What happens to the Cl transport channel if the CFTR gene is mutated?

Answer 5

The channel permeability is altered = Cl transport impaired

- This results in abnormal exocrine secretion systemically

Question 6

T or F:
Although the CFTR gene mutation prevents the transport of Cl out of a cell, Cl is still able to enter the cell through its basal membrane.

Answer 6

T

Question 7

Why is water and Na reabsorbed from mucus into cells as a result of cystic fibrosis? How does this contribute to the patho of cystic fibrosis?

Answer 7

• Because the Cl concentration in cells is high, water and Na are reabsorbed from mucus
• This causes the mucus to become thick and sticky due to a lack of water, this makes it very difficult for the cilia to move
• This thick mucus is a very ideal environment for bacteria to grow

Question 8

T or F:

In cystic fibrosis there is an excess of mucus.

Answer 8

F, the mucus become thicker and stickier, but there is no increase in its secretion

Question 9

How does cystic fibrosis affect the respiratory system?

Answer 9

• Thick mucus = decreased ciliary Fx = airway obstruction = impaired breathing
• Increased bacterial infections
• Death due to severe pulmonary complications

Question 10

Explain the sweat test:

Answer 10

• Dx test for cystic fibrosis
• Collect sweat from pt and measure concentration of NaCl in it
  
  • NaCl concentration is 2-3x higher with cystic fibrosis
  • This is because Cl cant be excreted from cell and
    Na is reabsorbed

Question 11

What is the newborn screen for cystic fibrosis?

Answer 11

• Measuring for increased levels of trypsinogen in blood
• In someone without cystic fibrosis, trypsinogen should move from the pancreas to the duodenum, but can’t in cystic fibrosis d/t secretory obstruction

Question 12

What 2 systems does cystic fibrosis mnft symptoms in?

Answer 12

• Respiratory

- GI tract

Question 13

What is the Tx/cure for cystic fibrosis?

Answer 13

• No cure
• Symptom management, slow progression
• Treat infections that may arise
  
  • Antibiotics, gammaglobulins, mucolytics
• Chest physio
• DNAse
  
  • Break down DNA strands that are released by dead
    cells, this will decrease viscosity of mucus
• Diet modifications
  
  • Address NaCl losses
  • Supplement vitamins A, D, E, and K
  • Supplement enzymes (?)

Question 14

Why do you need to supplement vitamins A, D, E, and K in people with cystic fibrosis?

Answer 14

Because these vitamins are fat-soluble, meaning they need fat to be absorbed, but in cystic fibrosis the absorption of fats in defective