Question Answer
Which of the following does NOT increase the affinity of Hb for oxygen? D) Increased temperature
What is the affect of an elevated intracellular 2,3-DPG concentration? C) Increases the availability of oxygen to the tissues.
Which of the following would you expect to find with “oxygen debt”? B) I and II I. Accentuated in diseases such as sepsis. II. Oxygen demand exceeds oxygen delivery.
Regarding pulmonary blood flow in the upright lung, which of the following statements is true? B) The bases receive about 20 times more blood flow than the apexes.
The time available for diffusion in the lung is mainly a function of which of the following? D) Rate of pulmonary blood flow
A 70-kg male patient has a VCO2 of 200 ml/min and a VA of 9 L/min. From this information, what can you infer? C) The patient will have a lower than normal PACO2.
Why is it necessary to keep the patient’s PaO2 greater than 60 mm Hg? A) A level of 60 mm Hg marks the beginning of the steep part of O2Hb dissociation curve.
The highest PCO2 levels are found in what location? C) Cells
At body temperature, how much oxygen will physically dissolve in plasma at a PO2 of 40 mm Hg? A) 0.12 ml/dl
What does V/Q mismatch have the biggest impact on? C) Oxygenation
A patient has a P50 value of 29 mm Hg. What does this indicate? A) Decreased affinity of Hb for oxygen.
An area of the lung has no ventilation but is normally perfused by the pulmonary circulation. Which of the following statements are correct? D) I, II, and III I. Blood exiting the pulmonary capillary will have a PO2 = 40 and a PCO2 = 46. II. The area represents an alveolar shunt. III. The V/Q is 0.
Which of the following conditions must exist for gas to move between the alveolus and pulmonary capillary? B) Difference in partial pressures (pressure gradient)
The expected PaO2 for an 80-year-old man who is otherwise in good health and breathing room air is about what level? B) 75 mm Hg
What is the approximate normal CaO2 – CvO2 in a healthy adult at rest? A) 5 ml/dl
When Hb saturation with oxygen is high, less carbon dioxide is carried in the blood. What is this relationship called? D) Haldane effect
As the amount of oxygen that dissolves in the plasma increases, what is it directly proportional to? A) Its partial pressure
Which of the following best represents the partial pressures of all gases in the normally ventilated and perfused alveolus when breathing room air at sea level? B) PO2 = 100 mm Hg; PCO2 = 40 mm Hg; PN2 = 573 mm Hg; PH2O = 47 mm Hg
Which of the following “layers” must be traversed by gases moving across the alveolar-capillary membrane? A) I, II, and III I. Alveolar epithelial membrane II. Capillary endothelial membrane III. Interstitial space IV. Transbronchial radial tethering mechanisms
In a person breathing room air (and with all else being normal), if the alveolar PCO2 rises from 40 to 70 mm Hg, what would you expect? A) PAO2 to fall by about 30 mm Hg
Which of the following values corresponds most closely to the normal PO2 and PCO2 in the mixed venous blood returning to the lungs from the right side of the heart? A) PO2 = 40 mm Hg; PCO2 = 46 mm Hg
In which of the following conditions will erythrocyte concentration of 2,3-DPG be decreased? B) Banked blood
According to the Fick principle, if oxygen consumption remains constant, an increase in cardiac output will manifest itself as which of the following? A) Decrease in the CaO2 – CvO2
The oxidation of the Hb molecule’s iron ions to the ferric state (Fe3+) results in which of the following? C) II and III II. Formation of methemoglobin (metHb). III. Inability of metHb to bind with oxygen.
Carbon dioxide is most commonly elevated due to significant pulmonary disease that results in small tidal volumes. B) True
What is the most important component in the oxygen transport system? C) Hb
According to the Bohr effect, when the pH drops (blood becomes more acidic), what happens? A) I and II I. The affinity of Hb for oxygen decreases. II. The Hb saturation for a given PO2 falls.
Which of the following are potential causes of hypoxia? D) I, II, and III I. Decrease in arterial PO2. II. Decrease in available Hb. III. Decrease in cardiac output.
When a Hb molecule accumulates excessive amounts of HCO3-, it is expelled from the cell in exchange for Cl-. What is this called? C) Hamburger phenomenon
If the total hemoglobin content (Hb + HbO2) of a sample of blood is 20 g/dl and the oxyhemoglobin (HbO2) content is 15 g/dl, what is the HbO2 saturation? C) 75%
In which of the following forms is carbon dioxide transported by the blood? D) I, II, and III I. Chemically combined with proteins II. Ionized as bicarbonate (HCO3-) III. Simple physical solution
Under normal physiologic circumstances, how many milliliters of oxygen are capable of combining with 1 g of Hb? D) 1.340 ml
A patient has a whole-body oxygen consumption of 320 ml/min and a measured CaO2 – Cv O2 of 8 ml/dl. What is the cardiac output? B) 4.0 L/min
On what does the movement of gases between the lungs and the body tissues mainly depend? B) Gaseous diffusion
What occurs in the bases of the upright lung? D) The V/Q is lower than the average.
Which of the following equations best describes oxygen delivery to the tissues? B) arterial oxygen content x cardiac output
An abnormal metabolic state in which the tissues are unable to utilize the oxygen made available to them best describes which of the following? B) Dysoxia
Compared to normal levels, a shift in the HbO2 curve to the right has which of the following effects? B) I and II I. The affinity of Hb for oxygen decreases. II. The Hb saturation for a given PO2 falls.
What role does the Bohr effect play in oxygen transport? C) Enhances oxygen delivery to tissues and oxygen pickup at lungs.
What is the most common cause of hypoxemia? D) V/Q mismatch
The affinity of Hb for carbon monoxide (CO) is approximately how many times greater than its affinity for oxygen? D) 200 or greater
Under what conditions will the alveolar PACO2 rise above normal? C) If VA decreases relative to carbon dioxide production.
The lowest PO2 would normally be found in what location? C) Cells
Given the following blood parameters, compute the total oxygen content (dissolved + HbO2) of the blood in ml/dl: Hb = 16; PO2 = 625 Hg; SO2 = 100%. D) 23.3 ml/dl
Which of the following are true regarding fetal hemoglobin (HbF)? C) It delivers more oxygen to tissues at low PaO2 than normal Hb.
Which of the following gases would diffuse fastest across the alveolar-capillary membrane? B) Carbon dioxide
What is the minimum amount of time that blood must take for pulmonary capillary transit for equilibration of oxygen to occur across the alveolar-capillary membrane? B) 0.25 second
Even in healthy young subjects, regional differences in pulmonary ventilation and blood flow result in the PaO2 being lower than the PAO2. Why is this so? C) Most blood flows through the bases of the lung.
What is the highest PAO2 one could expect to observe in an individual breathing room air at sea level? B) 110 to 120 mm Hg
Given the following blood parameters, compute the total oxygen content (dissolved + HbO2) of the blood in ml/dl: Hb = 18; PO2 = 40 mm Hg; SO2 = 73%. B) 17.7 ml/d