A research scientist attempts to understand the influence of carbon dioxide content in blood on its oxygen binding. The scientist adds carbon dioxide to dog blood and measures the uptake of oxygen in the blood versus oxygen pressure in the peripheral tissue. He notes in one dog that with the addition of carbon dioxide with a pressure of 90 mmHg, the oxygen pressure in the peripheral tissue rose from 26 to 33 mmHg. How can this phenomenon be explained?
AHigh partial pressure of CO2 in tissues decreases peripheral blood volume
BBinding of O2 to hemoglobin in lungs drives release of CO2 from hemoglobin
CHigh partial pressure of CO2 in tissues causes alkalemia, which is necessary for O2 unloading
DHigh partial pressure of CO2 in tissues facilitates O2 unloading in peripheral tissues
EThe sum of the partial pressures of CO2 and O2 cannot exceed a known threshold in blood
A 44-year-old male immigrant presents to his primary care physician for a new patient visit. The patient reports chronic fatigue but states that he otherwise feels well. His past medical history is not known, and he is not currently taking any medications. The patient admits to drinking 7 alcoholic beverages per day and smoking 1 pack of cigarettes per day. His temperature is 99.4°F (37.4°C), blood pressure is 157/98 mmHg, pulse is 99/min, respirations are 18/min, and oxygen saturation is 100% on room air. Physical exam demonstrates mild pallor but is otherwise not remarkable. Laboratory studies are ordered as seen below. Hemoglobin: 9 g/dL Hematocrit: 33% Leukocyte count: 6,500/mm^3 with normal differential Platelet count: 190,000/mm^3 Mean corpuscular volume (MCV): 60 femtoliters Free iron: 272 mcg/dL Total iron binding capacity (TIBC): 175 mcg/dL Ferritin: 526 ng/mL Reticulocyte count: 2.8% Which of the following is the most likely diagnosis?
AFolate deficiency
BBeta-thalassemia
CIron deficiency
DB12 deficiency
EHemolytic anemia
A 40-year-old female volunteers for an invasive study to measure her cardiac function. She has no previous cardiovascular history and takes no medications. With the test subject at rest, the following data is collected using blood tests, intravascular probes, and a closed rebreathing circuit: Blood hemoglobin concentration 14 g/dL Arterial oxygen content 0.22 mL O2/mL Arterial oxygen saturation 98% Venous oxygen content 0.17 mL O2/mL Venous oxygen saturation 78% Oxygen consumption 250 mL/min The patient's pulse is 75/min, respiratory rate is 14/ min, and blood pressure is 125/70 mm Hg. What is the cardiac output of this volunteer?
ABody surface area is required to calculate cardiac output.
BStroke volume is required to calculate cardiac output.
C250 mL/min
D5.0 L/min
E50 L/min
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