USMLE1 Physiology Exam
Questions with Correct
Answers
A 35-year-old, sexually active woman visits her gynecologist complaining of mild, right-
sided, lower abdominal pain but no other symptoms. There are no peritoneal signs. Her
surgical history is significant for an appendectomy at age 10. Her last period occurred
14 days ago. Which of the following endometrial changes corresponds to this stage of
the patient's menstrual cycle? - Answer-Growth of spiral arteries
-
Notes:
Proliferative and secretory stages of menstrual cycle.
A 71-year-old woman undergoes an elective sigmoid resection for recurrent
diverticulitis. On the second postoperative day, it is noted that her urinary output is
averaging only 35 to 45 mL/h. She is receiving 5% dextrose in half normal saline at a
rate of 100 mL/h. The intravenous rate of infusion is increased to 125 mL/h. Two days
later, her urinary output becomes 15 to 25 mL/h. A sample of urine shows a urinary
sodium concentration of 85 mEq/L. Laboratory studies show the systemic arterial values
as follows:
pH 7.25
pCO2 30 mm Hg
Bicarbonate 15 mEq/L
Potassium 5.8 mEq/L
BUN 85 mg/dL
Creatinine 5.1 mg/dL
Which of the following is the most likely diagnosis? - Answer-Acute renal failure
-
Notes: Normal urine output is ~30-35 mL/hr
Urinary output from 35 to 14 mL/hr = renal failure
A 47-year-old recent immigrant from Africa has significant edema of the left lower
extremity. A polymerase chain reaction assay for DNA of Wucheria bancrofti is positive.
Which sequence of the numbered statements below correctly describes the pathway of
the flow from the affected system on the affected side of the body?
1) Junction of left internal jugular and left subclavian
2) Lymph capillaries
3) Thin lymph vessels
, 4) Thoracic duct - Answer-2-3-4-1
-
Notes:
Lymph capp., lymph vessels, thoracic duct and left internal jugular and left subclavian
vein
The following data were collected from a normal patient before and after an
intervention. Assume that plasma osmolarity and glomerular filtration rate remain
constant.
Before and after
Urine osmolarity (mOsm/L) 900 to 250
Urine flow rate (mL/min) 0.65 to 2.3
Fractional clearance of sodium 1% to 1%
Osmolar clearance (mL/min) 2.0 to 2.0
The intervention that would best account for the observed changes is - Answer-
administration of lithium
-
Notes:
Lithium prevents urine from concentrating by increasing flow .
An unlabeled container of blood product is left in a laboratory. The technician must
determine whether the sample is serum or plasma. An elevated level of which of the
following substances would identify the specimen as plasma? - Answer-Fibrinogen
-
Notes:
Fibrinogen is only present in plasma.
Serum = plasma - fibrinogen
A Swan-Ganz catheter inserted into a patient with acute respiratory distress syndrome
(ARDS) records a pulmonary artery wedge pressure of 6 mm Hg. The same pressure
would be expected in which of the following structures? - Answer-Left atrium
-
Notes:
pulm vein, lung, pulm artery, left atrium
Increased pressure @ pulm artery = increased pressure upstream at left atrium
38) A hysterical patient is hyperventilating and doubles his aveolar ventilation. If his
initial alveolar PACO2 was 40 mm Hg and his CO2 production remains unchanged,
what will his alveolar PCO2 be on hyperventilation? - Answer-20 mm Hg
-
Notes:
PACO2 inital = 40 mm Hg
doubles aveolar ventilation (hyperventilates) = /2
Questions with Correct
Answers
A 35-year-old, sexually active woman visits her gynecologist complaining of mild, right-
sided, lower abdominal pain but no other symptoms. There are no peritoneal signs. Her
surgical history is significant for an appendectomy at age 10. Her last period occurred
14 days ago. Which of the following endometrial changes corresponds to this stage of
the patient's menstrual cycle? - Answer-Growth of spiral arteries
-
Notes:
Proliferative and secretory stages of menstrual cycle.
A 71-year-old woman undergoes an elective sigmoid resection for recurrent
diverticulitis. On the second postoperative day, it is noted that her urinary output is
averaging only 35 to 45 mL/h. She is receiving 5% dextrose in half normal saline at a
rate of 100 mL/h. The intravenous rate of infusion is increased to 125 mL/h. Two days
later, her urinary output becomes 15 to 25 mL/h. A sample of urine shows a urinary
sodium concentration of 85 mEq/L. Laboratory studies show the systemic arterial values
as follows:
pH 7.25
pCO2 30 mm Hg
Bicarbonate 15 mEq/L
Potassium 5.8 mEq/L
BUN 85 mg/dL
Creatinine 5.1 mg/dL
Which of the following is the most likely diagnosis? - Answer-Acute renal failure
-
Notes: Normal urine output is ~30-35 mL/hr
Urinary output from 35 to 14 mL/hr = renal failure
A 47-year-old recent immigrant from Africa has significant edema of the left lower
extremity. A polymerase chain reaction assay for DNA of Wucheria bancrofti is positive.
Which sequence of the numbered statements below correctly describes the pathway of
the flow from the affected system on the affected side of the body?
1) Junction of left internal jugular and left subclavian
2) Lymph capillaries
3) Thin lymph vessels
, 4) Thoracic duct - Answer-2-3-4-1
-
Notes:
Lymph capp., lymph vessels, thoracic duct and left internal jugular and left subclavian
vein
The following data were collected from a normal patient before and after an
intervention. Assume that plasma osmolarity and glomerular filtration rate remain
constant.
Before and after
Urine osmolarity (mOsm/L) 900 to 250
Urine flow rate (mL/min) 0.65 to 2.3
Fractional clearance of sodium 1% to 1%
Osmolar clearance (mL/min) 2.0 to 2.0
The intervention that would best account for the observed changes is - Answer-
administration of lithium
-
Notes:
Lithium prevents urine from concentrating by increasing flow .
An unlabeled container of blood product is left in a laboratory. The technician must
determine whether the sample is serum or plasma. An elevated level of which of the
following substances would identify the specimen as plasma? - Answer-Fibrinogen
-
Notes:
Fibrinogen is only present in plasma.
Serum = plasma - fibrinogen
A Swan-Ganz catheter inserted into a patient with acute respiratory distress syndrome
(ARDS) records a pulmonary artery wedge pressure of 6 mm Hg. The same pressure
would be expected in which of the following structures? - Answer-Left atrium
-
Notes:
pulm vein, lung, pulm artery, left atrium
Increased pressure @ pulm artery = increased pressure upstream at left atrium
38) A hysterical patient is hyperventilating and doubles his aveolar ventilation. If his
initial alveolar PACO2 was 40 mm Hg and his CO2 production remains unchanged,
what will his alveolar PCO2 be on hyperventilation? - Answer-20 mm Hg
-
Notes:
PACO2 inital = 40 mm Hg
doubles aveolar ventilation (hyperventilates) = /2
