What happens in decreased lung compliance?

Ans: a (Increased RR & decreased TV)Ref: Ganong, 22nd ed. pg. 654Compliance is the stretchability of lung and chest wall. It is the change in lung volume per unit change in airway pressure.So as compliance decreases the stretchability of the lung decreases resulting in decreased tidal volume Whenever TV decreases, the body tries to maintain minute ventilation (TV x respiratory rate) by increasing the respiratory rate.So the best option is increase in RR and decrease in TV.Note: Compliance means flow of air through the lungs provided the pressure remains constant. Surfactant increases compliance of the lung.Surfactant: It is produced by type II pneumocytes as lamellar bodies secreted by exocytosis.Main composition:* Dipalmitoyl phosphatidyl choline (dipalmitoyl lecithin)-62%* Neutral lipids-13%* Proteins-8%* Phosphatidyl glycerol-5%Main functions* Reduces surface tension (according to Laplace law =P=2T/R)* Prevents pulmonary oedema* Prevents collapse of alveoli* Increase complianceSurfactant production is decreased by (ABCDGHI)* Arterial occlusion* Bronchial obstruction* Cigarette smoking* Diabetes mellitus* Glucocorticoid deficiency* Hypothyroidism* Inhalation of 100% oxygen RememberSurfactant deficiency is associated with HMD or IRDS (infant respiratory distress syndrome)Mutation of sp-c gene is associated with familial interstitial lung disease.Sp-A and sp-D proteins are of collectin family.