2,3-DPG effects on oxygen affinity — MCQs

A 27-year-old woman, gravida 2, para 1, at 26 weeks' gestation comes to the emergency department because of vaginal bleeding and epistaxis for the past 2 days. She missed her last prenatal visit 2 weeks ago. Physical examination shows blood in the posterior pharynx and a uterus consistent in size with 23 weeks' gestation. Her hemoglobin concentration is 7.2 g/dL. Ultrasonography shows an intrauterine pregnancy with a small retroplacental hematoma and absent fetal cardiac activity. Further evaluation is most likely to show which of the following findings?

A 2-day-old boy is examined on day of discharge from the newborn nursery. He was born at 39 weeks by vaginal delivery to a primigravid mother. The pregnancy and delivery were uncomplicated, and the baby has been stooling, urinating, and feeding normally. Both the patient’s mother and father have no known past medical history and are found to have normal hemoglobin electrophoresis results. Compared to adult hemoglobin, the infant’s predominant hemoglobin is most likely to exhibit which of the following properties?

A 19-year-old male college student is brought to the emergency department by his girlfriend complaining of intense pain. They had been playing outside in the snow when the patient started to have severe hand and feet pain. He says the pain is 9 out of 10 and causing him to have trouble moving his fingers and toes. He also reports some difficulty “catching his breath.” He notes that he has been tiring easily for the past month but thought it was because he was studying and going out late. On physical examination, the patient appears uncomfortable. Bilateral conjunctivae are pale. His hands are swollen and tender to palpation. Cardiopulmonary examination is normal. Hemoglobin is 9.0 g/dL. An electrocardiogram shows mild sinus tachycardia. Hemoglobin electrophoresis is performed, which confirms sickle cell disease. The patient’s pain is managed, and he is discharged on hydroxyurea. Which of the following is the most likely to occur as a result of the new medication?

A healthy 20-year-old male college student attempts to climb Mount Everest and travels to the Tibetan plateau by plane. Upon landing, he feels increasingly dizzy and fatigued. He notices that he is breathing faster than usual. What is the initial stimulus for the most likely acid-base disorder?

An investigator is studying the relationship between fetal blood oxygen saturation and intrauterine growth restriction using MRI studies. The magnetic resonance transverse relaxation time (T2) is inversely related to the concentration of deoxyhemoglobin so that high concentrations of deoxyhemoglobin produce a low signal intensity on T2-weighted MRI. In a normal fetus, the T2 signal is most likely to be the highest in which of the following vessels?

An investigator is conducting a study on hematological factors that affect the affinity of hemoglobin for oxygen. An illustration of two graphs (A and B) that represent the affinity of hemoglobin for oxygen is shown. Which of the following best explains a shift from A to B?

A 34-year-old woman comes to a physician for a routine health maintenance examination. She moved to Denver 1 week ago after having lived in New York City all her life. She has no history of serious illness and takes no medications. Which of the following sets of changes is most likely on analysis of a blood sample obtained now compared to prior to her move? Erythropoietin level | O2 saturation | Plasma volume

A 67-year-old man presents to the surgical clinic with swelling of his right leg, fever, and chills for 2 days. The maximum recorded temperature was 38.3°C (101.0°F) at home. His right leg is red and swollen from the dorsum of the foot to the thigh with an ill-defined edge. Venous stasis ulcers are present in both of his limbs, but those on the right have a yellow discharge. His vitals include the following: blood pressure is 120/78 mm Hg, heart rate is 94/min, temperature is 38.3°C (101.0°F), and respiratory rate is 16/min. On physical examination, there is tenderness and warmth compared with his normal leg. Dorsalis pedis pulses are present on both of the ankles. What is the most likely cause of the right shift of the hemoglobin dissociation curve for his condition?

A male infant is born at 27 weeks following premature rupture of membranes and a precipitous labor to a G4P3 female. Given the speed of delivery steroids are not given. Shortly after delivery he develops respiratory distress and the decision is made to administer surfactant replacement therapy. While the components of the surfactant used in surfactant therapy may vary based on institution, what is the main component of pulmonary surfactant produced by type II pneumocytes?

A 30-year-old woman presents to clinic for a routine checkup. She reports that she is in good health but that she felt short of breath on her hiking and skiing trip to Colorado the week prior. She explains that this was the first time she has gone that high into the mountains and was slightly concerned for the first few days because she felt chronically short of breath. She reports a history of childhood asthma, but this experience did not feel the same. She was on the verge of seeking medical attention, but it resolved three days later, and she has felt fine ever since. What other listed physiological change results in a physiologic alteration similar to that which occurred in this patient?