QUIZ 2 PDF

Question 1 Which is not true regarding the work of breathing? With obstructive lung disease (increased airflow resistance), minimum work requires higher rates of breathing. In normal lungs, total work of breathing is minimal at approximately 15 breaths/min. The work required to overcome airflow...

Question 1 Which is not true regarding the work of breathing? With obstructive lung disease (increased airflow resistance), minimum work requires higher rates of breathing. In normal lungs, total work of breathing is minimal at approximately 15 breaths/min. The work required to overcome airflow plus elastic resistance equals total work. With stiff lungs (increased elastic resistance), minimum work is performed at higher frequencies. Question 2 Under resting metabolic conditions, a healthy adult produces approximately how much CO2 per minute? 200 ml/min Question 3 Which of the following does not describe hypoventilation? alveolar ventilation (CO2 removal) is less than CO2 production B. low blood pH alveolar ventilation is more than CO2 production high CO2 level in the blood Question 4 Regarding distribution of ventilation, which is not true? The lungs have uneven ventilation in proportion to perfusion. Regional factors causing the uneven distribution are the differences in thoracic expansion and transpulmonary pressure gradients. the lung is a perfect organ for gas exchange in that it has a perfusion-ventilation ratio (V/Q) of 1. Expansion of the lower chest is approximately 50% greater than expansion of the upper chest. Question 5 Which is not correct regarding the distribution of ventilation? Alveoli at the bases expand more than alveoli at the apexes. Alveoli at the apexes having a larger resting volume than do alveoli at the bases. There is greater transpulmonary pressure gradient at the top of the upright lung. Alveoli at the apexes expand more during inspiration. Question 6 False statement regarding time constant: A lung unit has a short time constant if compliance or resistance is high. Question 7 Which of the following constitute the physiologic dead space? Anatomic dead space plus alveolar dead space Question 8 Which is the formula for minute ventilation? Tidal volume x frequency of breathing Question 9 For a healthy adult breathing 16 breaths/min and having a VT of 450 ml, what is the minute ventilation? 7.2 L/minute Question 10 In a healthy adult with a tidal volume of 500 ml, how much fresh gas goes to the alveoli for gas exchange? 350 ml Question 11 The normal dead space ratio is approximately how much? 30% (20-40%) Question 12 The physical tendency of an object to return to an initial state after deformation refers to which of the following? elasticity Question 13 Correct statement regarding resistance: resistance is lowest in the upper airways Majority of the frictional resistance comes from the tissue movement during breathing Airway resistance decreases as lung volume increases because the airways distend as the lungs inflate The total resistance is highest in the smaller airways because they are arranged in parallel Question 14 Which is not true regarding the pressure differences during breathing? During a normal breathing cycle, the glottis remains close. The pressure at the surface of the body (PBS) and PAO remain at zero (i.e., atmospheric) throughout the cycle A zero pressure in the trachea means the pressure in the trachea is equal to the atmospheric pressure Alveolar pressure (PA) is sub-atmospheric in the beginning of inspiration compared with the pressure at the airway opening (PAO). Question 15 At functional residual capacity (FRC), which is not true? The trans-airway pressure gradient also is zero Air flows out of the airway opening Airway opening and alveolar pressures are both zero The lung is at its resting volume Question 16 In patients with increased airflow resistance (obstructive lung disease), to maintain a minimum work of breathing the patient s tend to breath at this rate: slower Question 17 Applying the effect of gravity on ventilation and blood flow (perfusion), to improve oxygenation in a patient with a diseased left lung, the patient should be placed on which of the following? lying with the right side down Question 18 Which is the formula for minute ventilation? rate of breathing ( fB) x tidal volume (VT) Question 19 Which is the formula for computing the volume of gas reaching the alveoli (alveolar volume) in a healthy adult? Tidal volume (VT) – anatomic dead space (VD anatomic) Question 20 To accurately assess the alveolar ventilation in clinical practice, which of the following is the preferred formula? alveolar ventilation = fB ( tidal volume- physiologic dead space) Question 21 NOT TRUE regarding lung compliance: The combined compliance of the system (lung and the chest wall) is reduced to approximately half that of the individual components Obesity and kyphoscoliosis increases the combined compliance In healthy adults, the compliance of the lungs and chest wall are each equal to approximately 0.2 L/cm H2O. The lungs and chest wall each have their own compliance or distensibility. Question 22 Regarding the distribution of resistance, which is true? Considering the number of parallel airways together, the smaller airways have higher resistance to airflow than larger airways. Resistance is high when lung volume is high. Resistance decreases when lung volume increases. Based on Poiseuille's law, smaller caliber tubes will have lower resistance compared to bigger caliber tubes. Question 23 The work of breathing consists of which of the following? the work required to overcome resistance to airflow through the airways the work required to overcome the elastic forces and the frictional forces the work required to overcome the elastic recoil of the chest wall the work required to overcome the frictional forces minus the work required to overcome the elastic forces Question 24 Regarding dead space, which is not correct? Dead space is the volume of the gas that is wasted, or wasted ventilation. Alveolar dead space represents portion of the lungs which is perfused but not ventilated. Physiologic dead space consists of the anatomic and alveolar dead space The conducting airways consist the anatomic dead space Question 25 Which is not correct regarding the relationship of CO2 and alveolar ventilation? When a pressure is breathing deeper and faster, the CO2 in the blood and the alveoli becomes low. The partial pressure of CO2 in the alveoli and blood is directly proportional to its rate of removal by alveolar ventilation The partial pressure of CO2 in the alveoli and blood is directly proportional to its production (VCO2) The partial pressure of CO2 in the alveoli and blood is inversely to its rate of removal by alveolar ventilation Question 26 Which is not correct regarding minute ventilation? Hypoventialtion occurs when minute ventilation is low. Increasing the frequency of breathing with no change in the tidal volume increases the minute ventilation Minute ventilation decreases when breathing becomes faster when a steady tidal volume. Minute ventilation increases with increase in the frequency of breath or tidal volume or both Question 27 With hyperventilation, the following is true: respiratory alkalosis results Question 28 The pressure difference between the pressure at the airway opening and the pressure in the alveolar (gas space) region of the lungs refers to which of the following? Transairway pressure difference Question 29 Which is not present AT END-INSPIRATION: the muscle pressure is at its height alveolar pressure is higher than pressure at the airway opening, driving flow in the expiratory direction alveolar pressure has returned to zero the transpulmonary pressure gradient reaches the maximal value (for a normal breath) of approximately 10 cm H2O Question 30 Which is not a true statement regarding forces opposing inflation of the lungs? The lung has a tendency to move outward while the chest wall tends to move inward. The lung has a tendency to move inward while the chest wall tends to move outward. Resistance caused by gas flow through the airways account most of the frictional forces. The tissues of the lungs, thorax, and abdomen, along with surface tension in the alveoli represent the elastic force. Question 31 In a premature infant with an inadequate surfactant, which is not true? lung compliance is increased. The muscular work required to inflate the lung is high. This produces a collapsing force that increases lung recoil. The intraalveolar surface tension is abnormally high Question 32 Most (approximately 80%) of the frictional resistance to ventilation comes from the _____________________. frictional impedance caused by the movement of gas through the airways (airway resistance) Question 33 Before inspiration the pressure at the pleural space is subatmospheric, and is at which of the following? -5cmH20 Question 34 Which is not true about the PULMONARY SURFACTANT It reduces surface tension it has strong intramolecular attractive forces Ability to reduce surface tension decreases as lung volume increases; and increases as lung volume decreases which helps to stabilize the alveoli. It has weak intramolecular attractive forces Question 35 Because of the destruction of elastic tissue in emphysema, compliance is: increased Question 36 In pulmonary fibrosis where there is increased elastic recoil, compliance is decreased Question 37 To better understand the forces that the muscles (or/and the machine) have to overcome to generate ventilation, we use this formula: ∆Pressure = (Elastance x ∆Volume) + (Resistance x ∆Flow) Question 38 Respiration refers to the physiologic processes of O2 use at the cellular level. Question 39 Resistance caused by gas flow through the airways and tissue movement during breathing is called frictional. Question 40 Ventilation is the movement of air in and out of the lungs; between the external environment and the alveoli. Question 41 The volume of air measured either during inspiration or expiration I called tidal volume. Question 42 One of the most used measurement to assess the pulmonary system is one that joins the airways (PTAW) and alveolar region (PTA), called transpulmonary pressure difference. Question 43 For gas to flow from one point to another, there must be a __________ ___________ between the two points pressure difference/pressure gradient Question 44 This is created by intramolecular attraction of liquid molecules lining the alveolar surfaces and shrinks the lungs. Surface tension Question 45 Elasticity is the physical tendency of an object to return to an initial state after deformation. Question 46 This refers to the constant of proportionality between volume (V) and pressure (P) in an elastic system and is usually expressed in units of ml/cm H2O. Compliance Question 47 At FRC (functional resting volume), the lung is at its resting volume. Question 48 Obstructive lung disease increases the frictional work of breathing, whereas restrictive lung disease increases the elastic work of breathing. Question 49 Airway resistance decreases as lung volume increases because the airways distend as the lungs inflate. Question 50 Minute ventilation is normally driven by the production of CO2 and depends on the size of the person and his or her metabolic rate. Question 51 Alveolar ventilation must match CO2 production per minute to ensure acid-base balance. Question 52 The partial pressure of CO2 in the alveoli and blood is directly proportional to its production (VCO2) and inversely to its r ate of removal by alveolar ventilation. Question 53 An area in the lung which is ventilated but not perfused (no blood supply) is called a dead space. Question 54 The conducting airways including the nose and the mouth constitute the anatomic space. Question 55 The total volume of air moving in or out of the lungs per minute (L/min) is called minute ventilation.