Physiology NBME BRS - Respiratory System Practice Test Exam Questions and Answers

Physiology NBME BRS - Respiratory System Practice Test Exam Questions and Answers What is the equation for physiological dead space (V_d)? - ANSWER-V_d = V_t * (P_ACO2 - P_ECO2)/P_ACO2 Where V_t = tidal volume P_ACO2 = alveolar CO2 P_ECO2 = expired air PCO2 What is the equation for minute ventilation (MV)? - ANSWER-MV = TV * RR Where TV = tidal volume RR = resp rate What volumes are included in FRC (functional residual capacity)? - ANSWER-FRC = ERV + RV ERV = exploratory reserve volume RV = reserve volume Which capacities cannot be measured by spirometry? - ANSWER-Any that include RV What measurements are included in vital capacity (VC) aka forced vital capacity (FVC)? - ANSWER-Everything added except for residual volume What measurements are included in total lung capacity (TLC)? - ANSWER-Everything added, including residual volume What is FEV1 defined as? - ANSWER-Volume of air that can be expired in the first second of a max expiration What is a normal FEV1/FVC? - ANSWER-0.8 What measure or ratio is altered in individuals with *obstructive lung disease*? How? - ANSWER-FEV1/FVC decreased What measure or ratio is altered in individuals with *restrictive lung disease*? How - ANSWER-Both FEV1 and FVC are reduced, maintaining a normal FEV1/FVC (or even a slightly elevated) Is asthma restrictive or obstructive? - ANSWER-Obstructive Is fibrosis restrictive or obstructive? - ANSWER-Restrictive What is the equation for compliance involving pressure and volume? - ANSWER-C=V/P V=volume P=pressure Does the slope of a pressure-volume curve tell you compliance or elastance? - ANSWER-Compliance is the slope Define hysteresis. - ANSWER-Inflation of lungs follows a different curve than deflation (due to increase pressure to overcome surface tension) At what volume/capacity are the forces of the lung and chest wall equal and opposite? - ANSWER-FRC Do individuals with *emphysema* have higher or lower lung compliance? - ANSWER-Higher What is the equation for Laplace's law (collapsing pressure of alveolus, P) - ANSWER-P =2T/r Where T = surface tension r = radius of alveolus What cell type is surfactant synthesized by? - ANSWER-Type II pneumocytes What is the primary component of surfactant? - ANSWER-Dipalmitoyl phosphatidylcholine (DPPC) What date range does a fetus develop surfactant? - ANSWER-24-35 weeks What segment of the airway has the highest resistance? - ANSWER-Medium-sized bronchi What type of drug is isoproterenol? - ANSWER-Sympathetic Agonist What type of sympathetic receptors are found in the lung? - ANSWER-β_2 What is the effect of parasympathetic stimulation to the lungs? Sympathetic? - ANSWER-Parasymp: airway constriction Symp: airway dilation (via β_2) What pressure will a balloon catheter in the esophagus tell you? - ANSWER-Intrapleural pressure Is COPD obstructive or restrictive? - ANSWER-Obstructive What is the impact of restrictive lung diseases on lung volumes? - ANSWER-Decreases all If someone have an FEV1/FVC greater than 0.8, what is that a dead giveaway for? - ANSWER-Restrictive lung disease. A patient presents with all lung volumes reduced; do they have restrictive or obstructive disease? - ANSWER-Restrictive What is the normal value for PO2 in inspired air? - ANSWER-160mmHg (or 21% of 760mmHg) What is normal atmospheric pressure? - ANSWER-760 mmHg Once air is humidified in the trachea, what is the PH2O? - ANSWER-47mmHg Once air is humidified in the trachea, what is the new PO2? - ANSWER-150 mmHg What is the normal PO2 for alveolar air (assume it has equilibrated)? - ANSWER-100 mmHg What is the normal PO2 in the venous system? - ANSWER-40 mmHg What is the normal PCO2 in alveolar air (assume it has equilibrated)? - ANSWER-40 mmHg What is the normal PCO2 in the venous system? - ANSWER-46 mmHg Is CO diffusion or perfusion limited? - ANSWER-Diffusion Is O2 diffusion or perfusion limited under stress (emphysema, fibrosis, exercise)? - ANSWER-Diffusion limited Is O2 diffusion normally diffusion or perfusion limited? - ANSWER-Perfusion limited Is CO2 diffusion or perfusion limited? - ANSWER-Perfusion Is N2O diffusion or perfusion limited? - ANSWER-Perfusion continues...