Respiratory physiology Medical Physiology

Respiratory physiology Medical Physiology (University of Nairobi) Respiratory physiology RESPIRATORY PHYSIOLOGY 1. The partial pressure of oxygen in dry air inhaled by divers at a depth of 100 feet (4 atm) below sea level is approximately a. 160mmHg b. 320mmHg c. 640mmHg d. 1280mmHg e. none of the above 2. Two healthy women with identical tidal volumes are subjected to spirometry and blood gas measurements. Subject A doubles her tidal volume and decreases her respiratory rate to ½ of baseline. Subject B decreases her tidal volume to ½ of baseline and doubles her respiratory rate. Which of the following statements about the resulting alveolar ventilation in the two women is true? a. Alveolar ventilation is unchanged in both subjects b. Alveolar ventilation increases in both subjects c. Alveolar ventilation decreases in both subjects d. Alveolar ventilation increases in subject A and decreases in subject B e. Alveolar ventilation decreases in subject A and increases in subject B 3. Increased baroreceptor discharge acts via the medulla to a.  heart rate b.  stroke volume c.  vessel diameter d.  BP e.  renin secretion 4. A man breathing room air at sea level has an alveolar ventilation of 2L/min. The blood gases show a PaCO2 of 48mmHg and a PaO2 of 70mmHg. The alveolar oxygen tension (PaO2 ) is a. 150mmHg b. 110mmHg c. 100mmHg d. 90mmHg e. 60mmHg 5. Reduction of functional Hb associated with anaemia, met Hb, or CO poisoning does not produce hyperpnoea because the a. Blood flow to the carotid body is  b. Total arterial O2 content is maintained within normal range c. Carotid body chemoreceptors are stimulated d. Central chemoreceptors are stimulated e. pO2 of arterial blood is normal 6. During a normal inspiration, more air goes to the alveoli at the base of the lung than to the alveoli at the apex of the lung because a. The alveoli at the base of the lung have more surfactant b. The alveoli at the base of the lung are more compliant c. The alveoli at the base of the lung have higher V/Q ratios d. There is a more negative intra pleural pressure at the base of the lung e. There is more blood flow to the base of the lung Downloaded by Austine Wanjala () lOMoARcPSD|MCQs RESPIRATORY PHYSIOLOGY – DR. Waheeb AL-Kubati 2 7. The activity of the central chemoreceptors is stimulated by a. An increase in the pCO2 of blood flowing through the brain b. A decrease in the pO2 of blood flowing through the brain c. A decrease in the oxygen content of blood flowing through the brain d. A decrease in the metabolic rate of the surrounding brain tissue e. An increase in the pH of the CSF 8. Metabolic functions of the lung include all of the following EXCEPT a. Inactivation of bradykinin b. Inactivation of prostaglandins c. Inactivation of angiotensin II d. Synthesis of prostaglandins e. Synthesis of surfactant 9. Regarding V/Q differences in the lung a. In healthy individuals, anatomic dead space is less than physiologic dead space b. The relative change in blood flow from apex to base is less than relative change in ventilation c. Ventilation/perfusion differences are due to gravity d. Ventilation/perfusion ratio is low at the base e. All of the above 10. A spirometer can be used to measure directly a. Functional residual capacity b. Inspiratory capacity c. Residual volume d. Total lung capacity e. None of the above 11. Which of these statements is correct? a. Regular bronchioles are the most distal part of the respiratory tract to contain glands. b. Larynx do contain significant amounts of smooth muscle c. Goblet cells are abundant in the small bronchi and respiratory bronchioles d. Regular bronchioles contain simple cuboidal cells e. Elastic fibres are more abundant in the bronchi and bronchioles than the upper respiratory tract. 12. Spirometry can measure all except a. IC b. ERV c. FRC d. Vital capacity e. TV Downloaded by Austine Wanjala () lOMoARcPSD|MCQs RESPIRATORY PHYSIOLOGY – DR. Waheeb AL-Kubati 3 13. Which statement is false about anatomical dead space? a. Anatomical dead space varies with age b. Can be estimated by the Fowlers method c. Significantly large in shallow breathing d. Measured by plotting N2 concentration against expired volume as in Bohr’s method e. Estimated at around 150ml in a 75kg man with TV 500ml 14. Which of these does not affect diffusion rate? a. Surface area for diffusion b. Concentration gradient c. Solubility of gas d. Molecular weight of gas e. Thickness 15. Which of these statements is false regarding Pulmonary Resistance? a. Increase in pulmonary arterial pressure generally cause a fall in pulmonary resistance b. Pulmonary resistance is only 1/10 of systemic circulation resistance c. Increase of lung volume results in increase of resistance in extra alveolar vessels d. Acetylcholine has a good bronchiole smooth muscle relaxation effect e. Resistance in pulmonary capillaries increases at large lung volumes 16. When CO2 diffuses into blood in systemic capillaries most of it: a. Remains in solution as CO2 b. Converts to carbamino compounds c. Converts to bicarbonate ions in RBC d. Combines with Hb directly e. Combines with H2O in plasma to form carbonic acid Downloaded by Austine Wanjala () lOMoARcPSD|MCQs RESPIRATORY PHYSIOLOGY – DR. Waheeb AL-Kubati 4 17. Identify the inconsistent value at sea level a. Alveolar pCO2 = 40mmHg b. Alveolar pO2 = 100mmHg c. Alveolar PH2O = 47mmHg d. Alveolar PN2 = 573mmHg e. pO2 of inspired air = 130mmHg 18. Identify the inconsistent value in these measurements on a mixed venous blood sample obtained in a healthy person from IVC at sea level a. pO2 = 40mmHg b. pCO2 = 48mmHg c. PN2 = 620mmHg d. O2 content = 150ml/L blood e. CO2 content = 540ml/L blood 19. After inspiration commences the: a. Intrapleural pressure and intrapulmonary P both fall b. Intrapleural pressure falls and intrapulmonary P rises c. Intrapleural pressure falls and venous return decreases d. Intrapulmonary pressure rises and volume of the alveoli is momentarily unchanged e. Intrapleural pressure rises and venous return to heart decreases 20. Which one is not correct? A patient suffering from anaemia with an Hb concentration of 5g/100ml a. Decreased TPR b. Increased cardiac output c. Increased 2, 3 DPG in RBC d. PaO2 will be decreased e. O2 dissociation curve will be moved to right in peripheral capillaries Downloaded by Austine Wanjala () lOMoARcPSD|MCQs RESPIRATORY PHYSIOLOGY – DR. Waheeb AL-Kubati 5