Cystic Fibrosis

Question 1

cystic fibrosis

Answer 1

• defective Cl- transport across CM d/t issues with transport proteins/channels
• causes hypersecretion of fluid or abn composition of secretion
• exocrine problem - affects GIT, reprod tract, and resp system
• site specific

Question 2

etiology

Answer 2

• gene mutation of CFTR on Chr 7 (mutation = altered transmembrane exchange)
• genetic disorder - autosomal recessive (2 defective alleles)
• increased rates in Caucasian people

Question 3

patho

Answer 3

• CFTR codes for Cl channels on epithelial cell membranes
• mutation = Cl permb altered and impaired Cl transport (impact is tissue specific)
• normally, mucus is secreted into lumen of a/w and contains Cl, K, Na, and H2O
• mucous is thick -> cilia won’t sweep it so it stays on lining of a/w -> ideal environment for microbial growth = infection, inflmtn and inlfm damage

Question 4

respiratory patho

Answer 4

• thick mucous -> decreased ciliary fx -> aw obstr -> dyspnea
• bacterial infection (complx)
• hypercapnia and hypoxemia

Question 5

diagnosis

Answer 5

• Hx, Px
• resp and GI mnftns
• sweat test
• newborn screen (trypsinogen test)
• sibling hx
• labs

Question 6

sweat test

Answer 6

• NaCl is measured in sample of sweat
• [NaCl] will be 2-5x higher in pts with CF
• Cl- can’t be transported out of reabsorptive duct, so NaCl stays in sweat producing hypertonic sweat

Question 7

newborn screen

Answer 7

• blood test

- increased levels of trypsinogen in blood b/c there’s secretory obstr in pancreas

Question 8

treatment

Answer 8

• no cure
• slow down progression
• prevent infections (Abx, gamma globulins, mucous)
• diet modifications (avoid fats, supplement fat-soluble vitamins and enzymes)
• mucolytics, anti-inflm and chest PT to help expectorate mucus to increase gas exchange and decrease infection
• DNAase

Question 9

DNAase

Answer 9

enzyme that breaks down DNA in mucous making it more mobile and easier to expectorate

Question 10

explain how thick sticky mucus ends up lining the airway

Answer 10

with defective Cl transport protein, mucous doesn’t contain Cl. Cl builds up within the cytoplasm and is in greater [ ] within the cell than in the a/w. Water is drawn out of mucous and into the cell d/t imbalanced [ ] on either side of the CM, and Na follows water, therefore resulting in thick sticky mucus lining the a/w