Monday, April 11, 2011

1. The term "renal autoregulation" refers in part to the fact that
A. the kidney does not require blood flow to sustain its active transport
B. the kidney contains baroreceptors (pressure receptors) that contribute to the regulation of cardiac output
C. renal blood flow is relatively constant over a wide range of systemic arterial pressures
D. renal blood flow is not affected by activation of the sympathetic nerves that innervate the kidney
E. a combination of both C and D above

2. The nerves that innervate the kidney are essential for regulating which of the following?
A. Na-K-ATPase active transport pump rate
B. renal autoregulation of blood flow
C. urine volume and tonicity (osmolality)
D. all of the above
E. none of the above

3. Which of the following would be expected to cause renal inulin (or creatinine) clearance to increase?
A. dilation of the afferent arteriole
B. dilation of the efferent arteriole
C. constriction of the afferent arteriole
D. constriction of the efferent arteriole
E. both A and D above

4. Kidney inflammation may result in the appearance of albumin (a plasma protein) in the urine because
A. more albumin enters the proximal tubule in the glomerular filtrate
B. reabsorption of albumin from the proximal tubule is inhibited
C. secretion of albumin into the distal tubule and collecting ducts is increased
D. increased peritubular blood flow makes more albumin available for diffusion into the tubule
E. reduced active transport of sodium ion reduces cotransport of other substances, including albumin

5. As blood passes along the glomerular capillaries from the afferent to efferent arteriole, the net filtration pressure (DP - Dp)
A. increases
B. decreases
C. first decreases, reaches a minimum about half way along the capillary, then increases
D. first increases, reaches a maximum about half way along the capillary, then decreases
E. remains constant

6. Sodium is actively reabsorbed from the renal tubule in which of the following nephron segments?
A. proximal tubule
B. distal tubule
C. thick ascending limb of the loop of Henle
D. all of the above
E. none of the above

7. The rate of water reabsorption from the proximal tubule is determined primarily by the
A. rate of dissolved particle (solute) reabsorption from the proximal tubule
B. concentration of ADH (antidiuretic hormone) in the blood
C. osmotic pressure developed by plasma proteins in the proximal tubule
D. active transport of water molecules by the proximal tubule cells
E. passive filtration due to the high hydrostatic pressure in the proximal tubule

8. Urea has a higher concentration in the fluid that leaves the proximal tubule (and enters the loop of Henle) than in blood plasma because
A. urea is synthesized by proximal tubule cells
B. urea is secreted into the proximal tubule
C. urea is reabsorbed from the proximal tubule but at a lesser rate that water is reabsorbed
D. urea diffuses back into the proximal tubule because of the high urea concentration in the renal medulla
E. urea is actively transported into Bowman's capsule from the glomerular capillaries

9. In the proximal tubule, penicillin is
A. actively secreted into the tubule
B. actively reabsorbed from the tubule
C. passively reabsorbed from the tubule
D. metabolized by the tubule cells
E. neither secreted nor reabsorbed nor metabolized

10. At which sites would the concentration of creatinine be expected to be highest? (Note: assume the person is normally hydrated.)
A. glomerular filtrate
B. end of the proximal tubule
C. end of the loop of Henle
D. urine
E. the concentration would be the same in all of the above, since creatinine is neither secreted or reabsorbed

11. Suppose a person loses the function of half his nephrons because of renal degenerative disease. Assuming the person survives and reaches a new steady state and that body urea production remains normal, which of the following would be expected to decrease below normal?
A. plasma urea concentration
B. renal urea excretion
C. renal urea clearance
D. urine urea concentration
E. all of the above

12. The following values are measured for potassium ion in a human subject.
Plasma K+                   5 meq/liter
Urine K+                   50 meq/liter
Renal creatinine clearance 80 ml/min
Urine formation rate      1.5 ml/minute

This patient's potassium clearance is closest to which of the following?

A. 5 ml/minute
B. 7.5 ml/minute
C. 15 ml/minute
D. 50 ml/minute
E. 75 ml/minute

13. Assuming the subject in the preceding question is a normal adult, we can conclude that most likely potassium is

A. filtered but not secreted or reabsorbed
B. secreted but not filtered or reabsorbed
C. reabsorbed but not secreted or filtered
D. filtered and secreted
E. filtered and reabsorbed

Cardiovascular Pathophysiology MCQ test

  1. A one-month-old infant is taken to the pediatrician because of dyspnea, difficulty in feeding, and poor weight gain. Physical examination reveals tachypnea, a weak femoral pulse compared to the radial pulse, and a 30 mm Hg difference in systolic pressure between the upper and lower extremities. Which of the following is the most likely diagnosis?

    1. Aortic coarctation

    1. Aortic regurgitation

    1. Cardiac tamponade

    1. Heart failure

    1. Hypovolemia

  1. Uncontrollable bleeding from the umbilical stump of a neonate specifically suggests deficiency of which of the following coagulation factors?

    1. Factor VIII

    1. Factor IX

    1. Factor XII

    1. Factor XIII

    1. Von Willebrand's factor

  1. A high school basketball player passes out in the middle of a game. He is rushed to the emergency room, where he regains consciousness. He claims that just before he fainted, he had difficulty breathing and experienced palpitations. On physical exam, he has a bifid apical impulse and a coarse systolic murmur at the left sternal border. The echocardiogram reveals ventricular hypertrophy with asymmetric septal thickening. Which of the following would increase the intensity of his heart murmur?

    1. Elevating his legs

    1. Increasing sympathetic tone

    1. Performing the Valsalva maneuver

    1. Squatting

  1. A 58-year-old man with fainting spells and exercise intolerance is found to have a bicuspid aortic valve with marked aortic stenosis. Which of the following physical findings would be prominent in this patient?

    1. Diastolic murmur

    1. Heave at left parasternal border

    1. Loud S2 heart sound

    1. Loud S3 heart sound

    1. Weak peripheral pulse

  1. A 1-year-old child with frequent pulmonary infections has signs of mild congestive heart failure. On physical examination, he is found to have a harsh systolic murmur with no diastolic murmur. Cardiac catheterization shows increased oxygen saturation in the right ventricle. Two-dimensional echocardiography would most likely reveal

    1. aortic insufficiency

    1. mitral stenosis

    1. a patent ductus arteriosus

    1. a patent foramen ovale

    1. a ventricular septal defect

  1. A 47-year-old male enters the hospital emergency room after severing a major artery during a farm accident. It is estimated that the patient lost about 800 mL of blood. His blood pressure is 95/65 mm Hg. A decrease in which of the following would be expected in response to hemorrhage in this man?

    1. Heart rate

    1. Plasma renin activity

    1. Sympathetic nerve activity

    1. Total peripheral resistance

    1. Vagal nerve activity

  1. ear-old woman complains to her physician that she is chronically tired. She has lost several pounds in the past few months without a change in her diet. Blood tests indicate she has severe anemia (Hb < 7 g/dL). Further testing shows the presence of blood products in her stool and a large malignant tumor in her ascending colon.
Which of the following is likely to be decreased in this woman?

    1. Arterial O2 content

    1. Arterial O2 saturation

    1. Arterial PO2

    1. Cardiac output

    1. Heart rate

    1. Stroke volume

  1. An increase in which of the following best explains the mechanism by which the cardiac output increases in severe anemia?

    1. Arteriolar diameter

    1. Blood viscosity

    1. Peripheral vascular resistance

    1. Splanchnic blood flow

    1. Tissue oxygen tension

  1. A 57-year-old female with renal insufficiency has been on dialysis for thirteen years, but has failed to make her last two appointments. She presents to the emergency room in obvious distress with a blood pressure of 85/40 and jugular venous distension. Cardiac auscultation reveals no murmurs, thrills, or heaves. Her heart rate is rapid, at 108 beats/min, and the peripheral pulses are thready. Pulsus paradoxus is present, but Kussmaul's sign is absent. Echocardiography reveals the presence of a small heart. Which of the following is the most likely diagnosis?

    1. Cardiac tamponade

    1. Constrictive pericarditis

    1. Congestive heart failure

    1. Myocardial infarct

    1. Restrictive cardiomyopathy

  1. A 40-year-old man presents to his physician with complaints of chest pain. The pain is paroxysmal, substernal, and occurs while at rest. An electrocardiogram performed in the doctor's office shows ST segment elevations.

Which of the following is the most likely cause of the man's pain?

    1. Heartburn

    1. Hypertension

    1. Severe atherosclerotic narrowing of coronary arteries

    1. Thromboembolism of coronary arteries

    1. Vasospasm of atherosclerotic vessels
1. A 2. D 3. C 4. E 5. E 6. E 7. A 8. A 9. A 10. E

Thursday, April 7, 2011

Hyponatremia pathophysiology in liver cirrhosis: USMLE renal mcq question bank

A 64-year-old man is admitted with a 5-day history of  lethargy and mild confusion. He is known to have  alcoholic cirrhosis, nonbleeding esophageal varices, and ascites. There is no history of recent alcohol consumption, melena, or hematemesis. He has no abdominal pain and had not fallen. He takes a 2-g sodium diet and multivitamins daily. On examination, the patient is lethargic and confused to time and place but not date. Blood pressure is 110/70 mm Hg, pulse rate 87/min, temperature 36 °C (96.8 °F). Icteric sclerae and spiderangiomata are present. The neck veins are not distended. The lungs are clear, with decreased breath sounds at both bases. Cardiac examination reveals regular sinus rhythm and no gallop or rub. The abdomen is protuberant but nontender, with a shifting dullness; the liver is not palpable. The lower extremities have 1 + ankle edema. Asterixis is present, but the patient has no focal neurologic signs.

Laboratory studies:
Hemoglobin 11.5 g/dL
Hematocrit 32%
Leukocyte count 5400/µL
Platelet count 84,000/µL
Blood urea nitrogen 20 mg/dL
Serum creatinine 1.2 mg/dL
Serum sodium 114 meq/L
Serum potassium 4.1 meq/L
Serum chloride 80 meq/L
Serum bicarbonate 28 meq/L
Serum total protein 6.9 g/dL
Serum albumin 2.5 g/dL
Cholesterol 186 mg/dL
Serum osmolality 241 mosmol/kg H2O
Urine osmolality 200 mosmol/kg H2O
Spot urine sodium 10 meq/L

What is the cause of this patients hyponatremia?

A. Nonosmotic stimulation of antidiuretic hormone
B. Hepatorenal syndrome
C. Low-sodium diet
D. Reset osmostat
E. Pseudohyponatremia
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