Pulmonary Quiz 1 Flashcards
The compliance of the respiratory system is changing with lung volume. At which lung volume has the respiratory system its greatest compliance?
(a) RV
(b) TLC
(c) Minimal lung volume (below RV)
(d) FRC
D
Explanation: The slope of Volume/Pressure curve for the respiratory system thus the compliance of respiratory system is highest at FRC (Look at the curve in your handouts).
The relationship between volume and transmural pressure of a normal lung is illustrated by curve 3. Which curve or line of the figure represents this relationship for the lung of a patient with lung fibrosis?
(a) 1
(b) 2
(c) 4
(d) 5
C
Explanation: Compliance is reduced by fibrosis and 4 is the only option with a reduced Compliance in comparison to normal (curve 3). The line 5 shows a reduced compliance as well, but it shows a linear relationship between Volume and pressure, which makes it incorrect. Curve 2 does not present the correct relationship between lung volume and transmural pressure. Curve 1 indicates a higher compliance compared to normal.
Breathing is associated with changes in intra pleural pressure (Ppl). During which of the following respirations can this pressure become positive (greater than atmospheric pressure).
(a) During forced inspiration of a large volume (3 L)
(b) During normal expiration
(c) During normal inspiration
(d) During forced expiration of a large volume (3 L)
(e) During breath holding at FRC
D
Explanation: Pleural pressure is negative at FRC (-6 cm H2O), and decreases further during inspiration. During expiration it becomes less negative as compared to FRC, but is still negative. Only during forced expiration particularly if expired volume is large, pleural pressure can become positive.
A patient consults the doctor and complains over breathlessness. The doctor thinks he is suffering from lung emphysema. Therefore, he decides to measure the residual volume of the lung. After a maximal expiration, the Patient is connected with a bag containing a mixture of 2 liters air (Vbag = 2 l) with 2% He (FHe = 0.02). Helium concentration decreases to 1% (FHe = 0.01) after mixing of lung volume with the volume of the bag. What is the residual volume (RV) of the patient?
(a) 1.0 L
(b) 1.5 L
(c) 0.5 L
(d) 2.0 L
(e) 3.0 L
D
Explanation: FHe (before connection with the lung) x Vbag = FHe (after connection with the lung) x (Vbag + RV). It means: 0.02 x 2L = 0.01 x (2L + RV). Solving this equation for RV reveals: RV = 2L.
A healthy person connected to a spirometer has been asked to take a maximum breath in, hold it and then exhale as hard and fast as he can (forced vital capacity maneuver). The expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) have been measured. What is the normal value of FEV1/FVC in %.
(a) 40
(b) 80
(c) 60
(d) 100
(e) 20
B
Explanation: You should know the important normal values such as this one.
You are called to examine a premature early born infant. He is suffering from breathlessness and is cyanotic. Your diagnosis is “infant respiratory distress syndrome (IRDS).” After treatment with artificial surfactant, the situation is under control. What did surfactant do?
(a) It increased the activity of inspiratory motoneurons
(b) It increased the concentration of erythrocytes in the blood
(c) It decreased the lung compliance
(d) It increased the force of respiratory muscles
(e) It decreased surface tension in the lung
E
Explanation: It is the main effect of Surfactant to reduce surface tension and hereby increase compliance of the lung.
By which combination of the following respiratory pattern is the alveolar ventilation (VA) the greatest?
Tidal volume (VT) Respiratory frequency (FR)
(L) (breath / min)
(A) 0.25 24
(B) 0.5 12
(C) 1.0 6
(D) 2.0 3
(a) A
(b) C
(c) B
(d) D
D
Explanation: Total ventilation is equal to alveolar ventilation + dead space ventilation. It means (FR x VT) = (FR x VA) + (FR x VD). Therefore changes in FR affects all three ventilations proportionately, but changes in VT affects VA, but not VD (VD is virtually constant). In this question Total ventilation is the same by all choices. A decrease in FR decreases both alveolar and dead space ventilation, but increases in VT would only increase alveolar ventilation, but not dead space ventilation. Therefore a combination of highest VT and lowest FR for a given ventilation would result in the highest alveolar ventilation and lowest dead space ventilation.
The following may reduce the FEV 1 in a patient with chronic obstructive pulmonary disease:
(a) Administration of a bronchodilator drug
(b) Hypertrophy of the diaphragm
(c) Increased recoil force of the lung
(d) Increased inspiratory effort
(e) Loss of radial traction on the airway
E
Explanation: Radial traction of the airway means that the airway is pulling outwards (increasing transmural pressure) which in turn dilates the airway. Therefore, a loss of this force produces a narrowing of the airway and results in a decreased FEV1.
A person can modify his breathing voluntarily. Which of the following phases of inspiration or expiration is passive and does not require respiratory muscles force?
(a) Forced inspiration
(b) Slow inspiration of a small volume
(c) Normal expiration
(d) Normal inspiration
(e) Forced expiration to values below FRC
C
Explanation: Inspiration is always active, because the respiratory system (RS) is moved away from its resting volume during inspiration. Only normal expiration is passive, because the RS is moved towards its resting point by its recoiling force during a normal expiration.
Some diseases cause injury of alveolar surface (gas exchange region). Which type of the lung cells repairs this membrane?
(a) Alveolar macrophage
(b) Alveolar epithelia cell type II
(c) Clara cell
(d) Alveolar epithelia cell type I
(e) Brush cell
B
Explanation: Alveolar type II cells normally produce surfactant, but in injury they proliferate and repair the alveolar capillary membrane and then differentiate to alveolar type 1 cells.
A person connected to a spirometer has been asked to take a minimum breath in, hold it and then exhale as hard and fast as he can (forced vital capacity maneuver). The expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) have been measured. The value of FEV1/FVC is significantly below 80% by:
(a) Lung obstructive disease
(b) A healthy person
(c) Lung fibroids
(d) Lung restrictive disease
A
Explanation: FEV1/FVC is lower than normal (80%) by obstructive diseases, because of the higher airway resistance. FEV1 is lower than normal by a restrictive disease because VC is smaller than normal, so that the ration of the two is normal or slightly increased due to lower compliance and higher recoiling force of the lung.
A patient inhales 2 L of air ad holds his breath. At the beginning of inspiration his lung transmural pressure is + 5 cm H2O. During breath holding his lung transmural pressure is + 10 cm H2O. What is his lung compliance L /cm H2O?
(a) 0.5
(b) 0.2
(c) 0.1
(d) 0.4
(e) 0.3
D
Explanation: Compliance is defined as dV/dP. Inhaling 2 L means that lung volume increased by 2L, therefore, dV = 2L. Now pressure before inhalation of dV was 5 cm H2O and thereafter 10 cm H2O; therefore, dP = 10 – 5 = 5 cm H2O. C = dV/dP = 2L/5cm = 0.4 L/cm H2O.
The airway resistance of a healthy person has to be determined. Close to which lung volume do you expect to measure his highest resistance to expiratory airflow?
(a) FRC
(b) 60 % of VC
(c) TLC
(d) RV
D
Explanation: One factor affecting airway resistance is the lung volume. The higher the lung volume, the lower is airway resistance (see the curve in your handouts.) Among choices given here, is residual volume (RV) the lowest lung volume and is therefore associated with the highest airway resistance.
Two bubbles have the same surface tension, but bubble X has 3 times the diameter of bubble Y. The ratio of the pressure in bubble X to that in bubble Y is:
(a) 1 : 1
(b) 9 : 1
(c) 0.9 : 1
(d) 0.3 : 1
(e) 3 : 1
D
Explanation: Pressure in a bubble is = 2 times Surface tension divided by radius. Because the radius of bubble X is 3 times greater than radius of bubble Y, its pressure must be 1/3 of pressure in bubble Y. Therefore, the ration of pressures in 1/3 to 1 or 0.3 to 1
What is the volume of one mol ideal gas under STPD condition?
(a) 15.2 L
(b) 22.4 L
(c) 31.0 L
(d) 10.5 L
(e) 36.4 L
B
Explanation: This value can be calculated from ideal gas law under STPD conditions.
