Pulmonary Flashcards
Metaplasia in smokers
Respiratory epithelium is replaced by stratified squamous epithelium
Loss of mucociliary elevator –> smoker’s cough
Where does pain from diaphragm irritation get referred?
To the shoulder (C5) or to the trapezius ridge (C3, C4)
C3, 4, 5 keeps the diaphragm alive (phrenic nerve)
Clara cells/Club cells
Non ciliated cells with secretory granules that are needed for detoxification of noxious gases, surfactant production, and act as bronchiolar stem cells
Type 1 vs Type 2 pneumocytes
Type 1: simple squamous cells of the alveoli (thin for optimal gas exchange)
Type 2: cuboidal cells that produce surfactant. Also act as precursors to type 1 pneumocytes
What increases surfactant production
Glucocorticoids
Thyroid hormone
Where is cross sectional area highest in the lung and what is the velocity of air here?
Cross sectional area increases from trachea to the respiratory zone. Inc area = dec velocity
Velocity = Flow/Cross sectional area
Under normal conditions, is gas transfer in the lungs perfusion limited or diffusion limited?
Perfusion limited: inc cardiac output causes increased perfusion and increased uptake of O2
What conditions cause O2 to become diffusion limited?
Thickened alveolar capillary membrane (ex. fibrosis)
Dec SA for diffusion (ex. emphysema)
High altitude
Increased pulmonary blood flow (blood moves rapidly through the lung and cannot be completely saturated)
What is the effect of dec PAO2 on pulmonary vessels?
Causes hypoxic vasoconstriction to shift blood away from poorly ventilated regions of the lungs to well-ventilated regions
\What diffuses faster, O2 or CO2?
Equilibrate in about the same amount of time .25 secs (O2 has a higher driving pressure but CO2 is more soluble)
What causes a right shift in the oxygen-hemoglobin association curve?
Occurs when affinity of Hb for O2 is decreased and this facilitates unloading of O2 to tissue
**Inc PCO2, H+, temperature, and 2,3-DPG
What causes a left shift in the oxygen-hemoglobin association curve?
Occurs when affinity of Hb for O2 is increased
**Dec PCO2, H+, temp, 2,3 DPG
Does fetal Hb have a left or a right shift?
Left shift because it has greater affinity for O2 (because it has a lower affinity for 2,3 DPG than adults)
Ensures that oxygen can be delivered from mom to fetus
patients present with cyanosis and chocolate colored blood
Methemoglobinemia: oxidized form of Hb (Ferric, Fe3+) cannot bind O2 as well and is treated with methylene blue
Effects of CO poisoning
o Reduced oxygen delivery: CO binds to hemoglobin and decreases the O2 content of the blood
o Binding of CO to hemoglobin increases the affinity of remaining sites for O2 – causing a left shift and decreased O2 delivery to the tissues (because it remains bound to hemoglobin)
CXR shows trachea moving away from side of penumothorax
Tension pneumothorax
due to penetrating chest wall injury → trachea pushes to opposite side due to compression from air accumulation in the pleura, treat with insertion of chest tube to release air
What accounts for the rubber like properties of elastin?
Interchain cross-links involving lysine
Why is the phospholipid content of amniotic fluid checked?
To determine fetal lung maturity and screen for likelihood of neonatal RDS
Lecithin to sphingomyelin ratio (>2 = mature)
Lecithin = phosphatidylcholine
A-a difference in diffusion limitation
Increased
A-a difference in hypoventilation
Normal
ex. opioid use, muscular dystrophy
A-a difference in V/Q mismatch
Increased
When some regions of the lung are hypoventilated
A-a difference in shunt
Increased
Some areas of the lung receive no ventilation
Lung compliance: when is it highest and when is it lowest?
Highest at FRC: lung isnt inflated
Lowest at TLC: lung is stretched as far as it can go
Laplace’s equation
PRessure in the alveolus due to surface tension is inversely related to radius (smaller alveoli have higher pressire- more susceptible to collapse)
Surfactant role
Decreases surface tension when the radius decreases
Increases surface tension when the radius increases
**Prevents the collapse of small alveoli
Compliance and regions of the lungs
Apex: low compliance because the alveoli are stretched
Base: high compliance
Elastase is found in which cells?
Alveolar macrophages and neutrophils
Excess activity of elastase is a major contributor to emphysema
Swanz Ganz catheter measures?
Closely reflects left atrial and left ventricular end diastolic pressures
Dorsiflexion of foot causing calf pain
Homan sign
Indicates DVT
What should you suspect in a child with nasal polyps?
Cystic fibrosis
Patient has a decreased FEV1/FVC ratio
Characteristic of obstructive lung disease
Very decreased FEV1, decreased FVC
Inc TLC (due to air trapping in the lung)
Decreased diffusing capacity for CO (DLCO)
Pathogenesis of Emphysema
Obstructive lung disease
Caused by an imbalance of proteases and antiproteases: alveolar macrophages produce proteases in response to inflammation. Antiproteases (like a1-antitrypsin) keeps these proteases in check to prevent damage
Unbalanced regulation leads to destruction of the alveoli
Centriacinar emphysema
Caused by smoking (upper lobe damage)
Inc proteases relative to antiproteases
Panacinar emphysema
Due to a1-antitrypsin deficiency that prevents regulation of proteases (lower lobe damage)
Associated with liver damage (A1AT accumulates in the ER of hepatocytes)
Sputum has spiral shaped mucus plugs and crystals
Asthma
Charcot-Leyden crystals = aggregates of eosinophil major basic protein
Curshmann spirals = shed epithelium
Kartagener syndrome
Inherited defect of dynein arm, which is necessary for ciliary movement
Clinical triad: situs inversus, chronic sinusitis, and bronchiectasis
Are also usually infertile due to immotil sperm or impaired cilia of the fallopian tube
Restrictive lung diseases include:
Idiopathic pulmonary fibrosis
Pneumoconiosis
Sarcoidosis
Hypersensitivity pneumonitis
What drugs can cause pulmonary fibrosis?
Bleomycin Busulfan Amiodarone Methotrexate Radiation
Anthracosis
Black dust accumulation in the lung
Caplan syndrome
Coal workers pneumoconiosis associated with rheumatoid arthritis