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2/3 CF Case
CF Case
| Question | Answer |
|---|---|
| What chromosome band is the CFTR gene located on? | 7q.31.2 |
| What is bronchial cuffing? | surround a structure w/ fluid or cells, as w/ a cuff; bronchial wall thickening on CXR |
| What is bronchiectasis? | chronic dilation of bronchi or bronchioles c/b inflammatory disease or obstruction often associated w/ heavy sputum produxn (Greek: “ectasis” = “stretching”) |
| What are the most common bugs seen in CF? | S. aureus & H. flu early; P. aeruginosa later |
| What is CF? | CF is a disorder in EPITHELIAL TRANSPORT t/o the body affecting the FLUID SECRETION in exocrine glands, & GI, respiratory, & reproductive epithelial lining. Thick mucus clogs organ passages. |
| What are the most prominent clinical features of CF? | Malnutrition, Recurrent lung infections, CLD, Hepatic cirrhosis, Pancreatic insufficiency, Intestinal obstruction, Steatorrhea, Infertility. |
| What percent of whites are CF carriers? | 4% (1/25) |
| What chromosome is the CFTR gene on? | 7 |
| What is the most common mutation that causes CF? | ∆F508: accounts for 60-70% of mutations |
| What does the CFTR gene code for? | The CF Transmembrane Conductance Regulator (CFTR) gene encodes plasma Cl- channels of ductal epithelia. CFTR mutation is the 1o defect of CF. |
| What does a normally functioning CFTR do? | A normally functioning CFTR will inhibit ENaC!!! Located on the apical surface of exocrine epithelial cells, CFTR regulates intracytoplasmic transport of Na+. Its main function is to make sure the luminal fluid stays hypotonic. |
| Where is CFTR found? | pancreas, liver, lungs, digestive tract, reproductive tract & skin sweat glands |
| What are the 3 main types of epithelia affected by CFTR mutations? | Volume-absorbing (airways & distal intestinal epithelia). Salt-absorbing but not volume-absorbing (sweat duct). Volume-secretory (proximal intestine & pancreas) |
| What is the pathophysiology of lung disease in CF? | H2O follows Na+ back into cells when it should stay in mucus. (ENaC is not inhibited by CFTR so Na+ reabsorbed by cells). |
| What is the pathophysiology of pancreatic disease in CF? | CFTR mutation causes low bicarbonate, Na+, & water secretion -> low release of pancreatic enzymes. |
| What is the pathophysiology of CF in the intestines? | Intestinal epithelium – no Cl- secretion, so Na+ & H2O don’t follow -> secreted mucins & other macromolecs not flushed from crypts -> obstruction. |
| What is the pathophysiology of CF in the sweat glands? | Sweat Glands: normal CFTR reabsorbs luminal Cl- ions & augments Na+ reabsorption via ENaC. CF pts secrete normal volumes of sweat, but they can't absorb Na+ as it moves thru the sweat duct, so sweat stays salty. |
| What is the pathophysiology of CF in the bones? | Can't absorb fat-soluble vitamins like Vit D, so bone & jt pain may occur. Pts also suffer from ↑ed bone reabsorption (osteoclast activity). Arthropathy (12%) & osteoporosis (38-77%) are common. |
| What are the PFTs of restrictive lung disease? | Decreased: TLC, RV, DLCO, FVC. Normal or decreased: RV/TLC ratio, FEV1. Normal or increased: FEV1/FVC ratio |
| What are the PFTs of obstructive lung disease? | Increased: TLC, RV, DLCO, RV/TLC ratio. Decreased: FVC, FEV1, FVC/FEV1 ratio. |
| What are the PFTs for combined obstructive & restrictive lung disease? | Decreased: TLC, FVC, FEV1. Increased: RV/TLC ratio (means air trapping). Normal or increased: RV. Variable: DLCO |
| What is hypoxIA? | ↓ed O2 delivery to, or utilization by, the TISSUES. Hypoxemia is one (but not the only) cause of tissue hypoxia. |
| What is hypoxIA? | ↓ed O2 delivery to, or utilization by, the TISSUES. Hypoxemia is one (but not the only) cause of tissue hypoxia. |
| What is hypoxIA? | ↓ed O2 delivery to, or utilization by, the TISSUES. Hypoxemia is one (but not the only) cause of tissue hypoxia. |
| What is hypoxIA? | ↓ed O2 delivery to, or utilization by, the TISSUES. Hypoxemia is one (but not the only) cause of tissue hypoxia. |
| What is hypoxEMIA? | ↓ed arterial pO2. N > 60mmHg – anything below = hypoxemia. |
| What is a ventilation/perfusion (V/Q) mismatch? | Always causes hypoxemia & ↑ed A-a gradient. Ventilation of lungs that aren’t perfused (not enough blood Q). Or perfusion of lungs (lots of blood Q) that aren’t ventilated.A-a gradient = (P alveolar O2) – (P arterial O2) |
| What is the source of DNA in CF sputum? | Leukocytes: specifically neutrophils. Sputum viscosity further ↑ed by excess extracellular DNA from chronic inflammation & neutrophil autolysis. |
| What is decreased bacterial killing in the lungs of CF pts due to? | ↓ed pathogen uptake by airway epithelia. Altered airway surface liquid composition. Impaired innate immune factors (NO, defensins). Decreased antibiotic penetration. |
| What are biofilms? | Bacterial virulence factors that interfere w/ phagocytosis & can allow bacteria to be up to 1000x more antibiotic resistant -> bacteria recovers, persists, spreads. |
| How does the innate immune response contribute to chronic lung infections in CF? | Chronic infexn & inflamm impair innate immunity. PMNs in airway survive longer d/t ++ produxn of stimulating factor->high # PMNs in airway. PMNs release O2 FRs that damage airway & elastase->too much protease activity. |
| What is alginate? | The biofilm of P. aeruginosa. It allows mucoid Pseudomonas to form microcolonies safe from antibodies & antibiotics. |
| Describe the treatment for acute pulmonary exacerbations in CF. | Antibiotics, Mucolytic agents, Bronchodilators |
| Describe lung development at week 4 gestation. | Lower respiratory organs begin developing. |
| When do the tertiary (segmental) bronchi develop? | Week 7 |
| What happens to terminal bronchioles at week 24 gestation? | They give rise to 2+ respiratory bronchioles. |
| What does each respiratory bronchiole divide into? | 3-6 tubular passages called alveolar ducts. |
| From what do the visceral pleura & parietal pleura form? | Visceral: splanchnic mesoderm; Parietal: somatic mesoderm |
| From what does the pulmonary circulation form? | 6th pharyngeal arch artery. |
| What are the 4 periods of lung development? | Pseudoglandular (6-16wks), Canalicular (16-26wks), Terminal saccular (26wks-birth), Alveolar (32wks-8yrs). |
| What are terminal saccules? | Terminal saccules arise from the ALVEOLAR DUCTS at the end of the RESPIRATORY BRONCHIOLES to allow respiration. They begin to form in the CANALICULAR PERIOD. |
| When do type I & II pneumocytes form & what do they do? | By the end of week 26. Type I: gas exchange occurs across these cells; Type II: secrete surfactant. |
| During what time frame does surfactant production occur? | 24-28 weeks it starts to be secreted & reaches adequate levels 2 weeks before birth. |
| Name 3 important factors in lung development. | Adequate thoracic space for lung growth, Fetal breathing movements, Adequate amniotic fluid volume. |
| How does the concentration of elastic fibers relate to the size of the conducting tube in the lungs? | It's inversely proportional. |
| What kind of epithelium is found in the majority of the conducting portion of the lungs? | Ciliated pseudostratified columnar epithelium with goblet cells. |
| What are the terminal bronchioles lined by? | Simple cuboidal epithelium with Clara cells that secrete granules that protect the bronchiolar lining. |
| List in descending order the structures from terminal bronchioles to alveoli. | Terminal bronchioles => Respiratory bronchioles => atria => alveolar sacs => alveoli |
| Describe the epithelial histology of the trachea & the primary bronchi. | CILIATED PSEUDOSTRATIFIED COLUMNAR with goblet cells, brush cells, neuro-endocrine cells, small granule cells, & short cells. |
| Describe the non-epithelial histology of the trachea & the primary bronchi. | Hyaline cartilage rings w/ sm. muscle in gaps; elastic/reticular adventitia. |
| Describe the histology of the intrapulmonary bronchi. | CILIATED PSEUDOSTRATIFIED COLUMNAR w/ goblet cells. Submucosal glands & plates of hyaline cartilage. |
| Describe the histology of the bronchioles. | CILIATED SIMPLE COLUMNAR w/ goblet cells; no cartilage or glands but sm. muscle. |
| Desrcibe the histology of the terminal bronchioles. | CILIATED CUBOIDAL - Clara cells (bulge into lumen) secrete protease inhibitors, oxidase, immunosuppressive pts, & neuroepithelial bodies. |
| Describe the histology of the respiratory bronchioles. | CILIATED CUBOIDAL - more Claras & less goblets – 1st gas exchange; few alveoli |
| Describe the histology of the alveolar ducts. | Type I pneumo’s (squame), type II pneumo’s (cube – secrete surfactant), alveolar MΦs, & capillary endothelial cells – reticular & elastic fibers. |
| Desribe the alveolar sacs. | Alveoli clusters forming alveolar duct ends |
| Describe the histology of the blood/air barrier (alveoli). | Type I pneumocytes – pneumocyte BM – capillary BM (may be fused w/ pneumo BM) – capillary endothelium. |
| What is clubbing? | Enlargement of distal tips of digits d/t connective tissue (CT) proliferation. Angle btn the nail bed & cuticle >160o (no diamond shape when you put fingers together). |
| What is the most accepted theory as to the cause of clubbing? | The Platelet Theory: Plt fragments lodge in sm vessels of fingertips &/or Plt-filled megakaryocytes travel to finger tips -> get stuck & occlude sm vessels. Then plts secrete PDGF which ↑es sm muscle & fibroblast proliferation. |
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