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
Which of the following physiologic changes decreases pulmonary vascular resistance (PVR)?
AInhaling the inspiratory reserve volume (IRV)
BExhaling the entire vital capacity (VC)
CExhaling the expiratory reserve volume (ERV)
DBreath holding maneuver at functional residual capacity (FRC)
EInhaling the entire vital capacity (VC)
A healthy 22-year-old male participates in a research study you are leading to compare the properties of skeletal and cardiac muscle. You conduct a 3-phased experiment with the participant. In the first phase, you get him to lift up a 2.3 kg (5 lb) weight off a table with his left hand. In the second phase, you get him to do 20 burpees, taking his heart rate to 150/min. In the third phase, you electrically stimulate his gastrocnemius with a frequency of 50 Hz. You are interested in the tension and electrical activity of specific muscles as follows: Biceps in phase 1, cardiac muscle in phase 2, and gastrocnemius in phase 3. What would you expect to be happening in the phases and the respective muscles of interest?
AIncrease of tension in experiments 2 and 3, with the same underlying mechanism
BIncrease of tension in all phases
CRecruitment of large motor units followed by small motor units in experiment 1
DFused tetanic contraction at the end of all three experiments
ERecruitment of small motor units at the start of experiments 1 and 2
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