Physiology Exam Answer Key

Physiology 1-All the following laboratory values are consistent with pulmonary fibrosis EXCEPT? a. b. c. d. e. Increased residual volume Increased vascular resistance Normal or above normal FEV1/FVC Decreased lung compliance Normal or above normal peak expiratory flow (corrected for lung volume) 2-Which of the following is INCORRECT regarding the above oxyhemoglobin curve? a. b. c. d. e. higher P50 than normal means that the O2 binds less tightly to Hb. HbF is normally shifted to the left An increase in PCO2 causes a right shift. An increase in blood pH increases P50. An increase in temperature shifts the O2 uptake curve to the right. 3-Regarding gas exchange across pulmonary capillaries, which of the following statements is FALSE? a. b. c. d. e. The length of capillary required for gas equilibrium is longer during exercise. In anemic person, DLCO is less than normal. At rest, equilibrium is usually reached at 50% of the capillary length CO2 crosses the membrane easier than O2. considering the diffusing capacity of the lung for different gases, the least important factor to play role is the molecular weight of the gas. 4-In a normal person breathing room air at sea level at rest (in standing position). All the following statements are true EXCEPT? a. Dead space accounts for almost one third of the tidal volume b. Volume of anatomic dead space ÷ volume of physiologic dead space is equal or greater than 1.0 c. Mixed venous [O2] is 15 ml/dl blood d. Physiologic dead space is greatest at the lung apex e. Compliance is greatest at the lung base. 5-In diving, divers first hyperventilate before they go into water. This hyperventilation allows one to hold one’s breath for a longer period of time, because hyperventilation: a. b. c. d. e. increases the oxygen reserve of systemic arterial blood decreases the PCO2 of systemic arterial blood decreases the pH of systemic arterial blood increases brain blood flow make alveolar air full of O2 which divers can use while diving 6-Which of the following is NOT true at FRC? a. It is about 75% TLC. b. The elastic recoil of the chest wall is outward. c. The elastic recoil of the lung is inward. d. The lung-thorax system is at rest. e. pulmonary vascular resistance is the lowest 7-While obtaining the arterial blood sample, the blood-gas technician draws room air into the syringe before measuring the blood-gas values. As a result, which of the following is true? a. The measured values of both PaO2 and PaCO2 will be higher than the patient’s actual values b. The measured values of both PaO2 and PaCO2 will be lower than the patient’s actual values c. The measured PaO2 will be higher and the measured PaCO2 will be lower than the patient’s actual blood gas values d. The measured PaO2 will be lower and the measured PaCO2 will be higher than the patient’s actual blood gas values e. The measured values of PaO2 and PaCO2 will accurately reflect the actual values 8-Regarding pulmonary vascular resistance a. b. c. d. e. is low at high lung volumes is low at low lung volumes if increased, can cause right heart failure is measured through routine pulmonary function tests is more than systemic vascular resistance. 9-Regarding dead space, choose the FALSE statement a. b. c. d. e. is defined as the volume of gas which does not take part in gas exchange physiological dead space is the same as alveolar dead space physiological dead space is measured by measuring mixed expiratory PCO2 mechanical ventilation (respirator) increases dead space volume. increases whenever V/Q ratio is increased 10-Which of the following sets of differences best describe the hemodynamics of the pulmonary circulation when compared with systemic circulation? Flow a. Same b. Same c. Higher d. Lower e. Higher Resistance Lower Higher Same Lower Higher Arterial P Lower Lower Higher Lower Higher 11-Regarding carbon monoxide poisoning, one of the following is TRUE: a. b. c. d. e. Increases firing rate from the peripheral chemoreceptors to the respiratory center decreases arterial O2 concentration Decreases arterial PO2 can be self-limited disease as long as PCO arterial is below 1 mmHg, we should not worry. 12-If 1 g of hemoglobin has an oxygen capacity of 1.34 mL of oxygen, what is the oxygen content of blood containing 10 g of hemoglobin when the blood PO2=40 mmHg? a. b. c. d. e. ≈ 6 mL/dL ≈ 8 mL/dL ≈ 10 mL/dL ≈ 12 mL/dL Cannot be calculated from the information provided 13-Which of the following decreases oxygen content but does not alter PaO2 or percentage saturation of hemoglobin? a. Ascent to an altitude of 3500 m b. Polycythemia (high RBC count) c. Breathing 50% oxygen d. Anemia e. Development of a large right-to-left shunt 14-In normal healthy person, if oxygen is added to inspired air to increase arterial PO2 from 100 mmHg to 300 mmHg, choose the correct statement a. b. c. d. e. dissolved oxygen will increase three-fold. the oxygen content of the blood will increase approximately three-fold the PaN2 will remain the same the PaCO2 will decrease to one third-normal Increasing arterial PO2 from 100 mmHg to 300 Hg can correct any form of hypoxia. 15-Which of the following conditions would result in the highest oxygen content per milimeter of blood? a. b. c. d. e. Hemoglobin concentration= 5 PaO2=90 mmHg Hemoglobin concentration= 5 PaO2=500 mmHg Hemoglobin concentration=3 PaO2=90 mmHg Hemoglobin concentration=10 PaO2=60 mmHg Hemoglobin concentration=16 PaO2=28 mmHg 16-According to the Law of Laplace, small alveoli don’t coexist with large alveoli at the same region. In the lungs, several factors counter that tendency, and stabilize the alveolar structures. Which of the following is NOT one of them? a. Surfactant lowers surface tension to a greater degree when it is on a smaller surface area, allowing the smaller alveoli to stay open. b. Mechanical stability is given by surrounding alveoli (alveoli support each other’s =alveolar interdependency) c. Intrapleural pressure is lower (more negative) for smaller alveoli, allowing them to stabilize in comparison to the bigger ones. d. Surface tension increases as alveolar surface area increases. e. surfactant makes surface tension volume-dependent 17-Which of the following is NOT true concerning respiratory distress syndrome in premature infants? a. b. c. d. e. Their ability to synthesize surfactant is limited. Higher pressures are required to ventilate the lungs. Lung compliance is low. Positive pressure respirators are often used to assist them in breathing. Alveoli tend to overexpand and sometimes burst at the end of inspiration. 18. Alveolar ventilation normally increases above normal when breathing: a. b. c. d. e. 21 % oxygen and 79 % nitrogen. 17 % oxygen and 83 % nitrogen. 2 % carbon dioxide and 98 % oxygen. 100 % oxygen and 0 % carbon dioxide. air available in Jordan Valley (‫)غور ا ألردن‬ 19-Which of the following is FALSE concerning the closing volume for the lung? a. b. c. d. Measured using the single breath N2 washout curve. Marks the point where the alveoli at the apex close. Marks a sudden increase in nitrogen concentration in the expelled breath. Marks when the overinflated, poorly ventilated alveoli at the apex expel their air with high N2 concentrations. e. It increases in smokers and in chronic bronchitis 20-If respiratory minute ventilation and rate of CO2 production are kept constant, the arterial PCO2 can be reduced by increasing: a. b. c. d. e. functional residual capacity. FiO2 (fraction of inspired O2) breathing frequency. tidal volume. local temperature 21-In normal resting individual breathing room air at sea level, voluntary trebling (3x normal) of alveolar ventilation: a. b. c. d. e. raises plasma pH. raises alveolar PCO2 . trebles the partial pressure of oxygen in the alveoli. raises arterial blood oxygen saturation by 3 %. raises arterial blood oxygen content by 3 %.