Physiology Exam II

Choose the

 

most correct answer.

1. Intravenous infusion of 1 liter of 3% saline would cause which of the following changes after osmotic equilibrium?

 Intracellular Volume Intracellular Osmolarity Extracellular Volume Extracellular Osmolarity

2. A 5 year old male child is brought to your office by his parents who state that he has had diarrhea for several days. He now weighs 18 kg and his parents indicate that he previously weighted 20 kg.  He is weak and appears to be dehydrated.  Lab test provide the following results:

Plasma osmolarity: 270 mosm/L
Urine osmolarity: 1200 mosm/L
Blood pressure: 100/56 mmHg

Approximately how much NaCl would be required to restore his total body osmoles (not his osmolarity, we'll assume appropriate hydration will be administered) to normal, assuming that before his bout of diarrhea his plasma osmolarity was 280 mosm/L, extracellular fluid volume was 20% of body weight, and intracellular fluid volume was 40% of body weight?  Assume no excretion of solutes or water during saline infusion.  The molecular weight of NaCl is 58.5.  I am very sure that you all know that 1 L of water weighs 1 kg.

a. 17.4 gm
b. 18.5 gm
c. 20.7 gm
d. 34.8 gm
e. 37.0 gm
f. 38.6 gm

3. If you administer 2.0 L of 0.9% NaCl, (286 mOsm/L), calculate the approximate plasma osmolarity of the patient in question #2, assuming osmotic equilibrium and no excretion of solutes or water?  Assume that the conditions are the same as stated in question #2 after diarrhea but before any treatment.

a. 265 mosm/L
b. 273 mosm/L
c. 279 mosm/L
d. 283 mosm/L
e. 290 mosm/L

4. If a person has a kidney transport maximum for glucose of 350 mg/min, a glomerular filtration rate of 110 ml/min, a plasma glucose of 375 mg/dl, and a urine flow rate of 3.0 ml/min, what would be the approximate rate of glucose excretion, assuming normal kidneys?

a. glucose excretion cannot be estimated from these data
b. 0 mg/min
c. 25 mg/min
d. 60 mg/min
e. 180 mg/min

5. You wish to evaluate kidney function in a 65 year old male and ask him to collect his urine over a 24 hours period.  He returns to you 4320 ml of urine, collected over the preceding 24 hours.  The clinical lab returns the following results from analysis of his urine and plasma samples:

Plasma creatinine: 3.0 mg/dl
Urine creatinine: 30 mg/dl
Plasma potassium: 5.0 mmol/L
Urine potassium: 10 mmol/L

What is his approximate glomerular filtration rate, assuming that he collected all of his urine in the 24 hour period?

a. 3 ml/min
b. 10 ml/min
c. 30 ml/min
d. 100 ml/min
e. 125 ml/min

6. What is the renal reabsorption rate of potassium in the patient described in question #5?
a. no potassium is being reabsorbed in this patient.
b. 0.03 mEq/min
c. 0.12 mEq/min
d. 0.15 mEq/min
e. 3.0 mEq/min
f. 30 mEq/min

7. What is the approximate potassium intake in the patient described in question #5, assuming steady state conditions, and that the patient collected all of his urine in the preceding 24 hours.

a. potassium intake cannot be estimated from the data given.
b. 32 mmole/day
c. 43 mmole/day
d. 51 mmole/day
e. 65 mmole/day

8. Which of the following changes would you expect to find as a result of a 50% increase in efferent arteriolar resistance?

 Renal Blood Flow Filtration Fraction Glomerular Capillary Hydrostatic Pressure Peritubular Capillary Hydrostatic Pressure
 
 
 

For questions 9-11, choose the appropriate nephron site in the diagram.
 
 
 

9. In a dehydrated patient with otherwise normal kidneys, which part of the tubule would have the lowest tubular fluid osmolarity?

10. In a patient with central diabetes insipidus, who is excreting 20 liters of urine a day, which part of the tubule would have the lowest tubular fluid osmolarity?

11. In a person with normal kidneys on a normal potassium diet, which part of the nephron reabsorbs the most potassium?

12. You are treating a 20 year old patient who was diagnosed with inappropriate ADH syndrome (excess ADH production).  Which of the following would you expect to fine under steady-state conditions in this patient, compared with normal and assuming a normal diet and fluid intake.

a. hyponatremia
b. decreased plasma renin activity
c. significantly decreased urine volume
d. decreased ANP levels
e. a and b
f. a, b and c
 

13. The clinical laboratory returns the following arterial blood values for a patient:
pH: 7.31
plasma HCO3-: 32 mmole/L
plasma PCO2 65 mmHg

What is the patient’s acid-base disorder?

a. acute respiratory acidosis without renal compensation
b. respiratory acidosis with partial renal compensation
c. acute metabolic acidosis without respiratory compensation
d. metabolic acidosis with partial respiratory compensation
e. not enough information is given to make an educated guess

14. In the patient described in question #13, which of the following laboratory values are you likely to find, compared to normal?

 Urine excretion of NH4+ Urine excretion of titratable acids Urine excretion of HCO3- Urine pH
 
 

15. The graph below illustrates the relationship between the plasma concentration of a hypothetical substance X and its reabsorption by the kidney.  The GFR is 100 ml/min.  The renal threshold for this substance is
 
 
 

a. 50 mg/dl
b. 100 mg/dl
c. 150 mg/dl
d. 200 mg/dl
e. 500 mg/dl

16. The Tmax for substance X is

a. 100 mg/min
b. 200 mg/min
c. 300 mg/min
d. 400 mg/min
e. there not enough information given to calculate the Tmax value

17. Sodium reabsorption from the distal tubule will be increased if there is an increase in

a. plasma potassium concentration
b. plasma volume
c. mean arterial pressure
d. urine flow rate
e. plasma osmolarity

18. If 600 ml of water is ingested rapidly, plasma volume will increase by approximately
a. 400 ml
b. 200 ml
c. 100 ml
d. 50 ml
e. 25 ml

19. The daily production of hydrogen ions from CO2 is primarily buffered by

a. extracellular bicarbonate
b. red blood cell bicarbonate
c. red blood cell hemoglobin
d. plasma proteins
e. plasma phosphates
 

20.The secretion of H+ in the proximal tubule is primarily associated with

a. excretion of potassium ion
b. excretion of hydrogen ion
c. reabsorption of calcium ion
d. reabsorption of bicarbonate ion
e. reabsorption of phosphate ion

21. If a substance appears in the renal artery but not in the renal vein,

a. its clearance is equal to the glomerular filtration rate
b. it must be reabsorbed by the kidney
c. its urinary concentration must be higher than its plasma concentration
d. its clearance is equal to the renal plasma flow
e. it must be filtered by the kidney
 
 

22. A freely filterable substance that is neither reabsorbed nor secreted has a renal artery concentration of 12 mg/ml and a renal vein concentration of 9 mg/ml.  Calculate the filtration fraction.

a. 0.15
b. 0.25
c. 0.75
d. 1.00
e. not enough information given to make this calculation

23. Renal correction of hyperkalemia will result in

a. alkalosis
b. acidosis
c. increased secretion of HCO3-
d. increased secretion of H+
e. increased excretion of Na+

24. Which of the following is most likely to cause an increase in the glomerular filtration rate?

a. contraction of mesangial cells
b. blockage of the ureter
c. release of renin from the juxtaglomerular apparatus
d. dilation of the afferent arterioles
e. volume depletion

25. Hypoxemia (arterial PO2 = 55 mmHg) has all the following effects EXCEPT

a. it stimulates carotid body chemoreceptors
b. it stimulates central chemoreceptors
c. it stimulates aortic chemoreceptors
d. it causes a reflex increase in ventilation
e. it causes an increase in blood flow to the zone 1 of the lung

26. A spirometer can be used to measure directly

a. functional residual capacity
b. inspiratory capacity
c. residual volume
d. total lung capacity
e. none of the above

27. The following figure shows two ventilation patterns: one normal and the other abnormal.  Assume that the inspiratory capacity is well above normal in the abnormal reading.  Which experimental maneuver listed below will create the abnormal pattern?
 

a. mid pons transection with vagi intact
b. transection of the brain stem between the pons and medulla
c. mid pons transection with vagi cut
d. transection rostral to the pons with vagi cut
e. transection rostral to the pons with vagi intact

28. A man breathing room air at sea level has a PACO2 of 48 mmHg.  His alveolar oxygen tension (PAO2) is:

a. 150 mmHg
b. 110 mmHg
c. 100 mmHg
d. 90 mmHg
e. 60 mmHg

Questions 29 and 30

The diagram below illustrates the change in intrapleural pressure during a single breath.
 
 

29. At which point on the diagram is inspiratory airflow the greatest?

a. A
b. B
c. C
d. D
e. E

30. At which point on the diagram is lung volume the greatest?

a. A
b. B
c. C
d. D
e. E

Questions 31-33

Use the pulmonary values below to answer the following questions

Tidal volume = 500 ml
Respiratory rate = 15/min
Expired PCO2 = 40 mmHg
Alveolar PCO2 = 50 mmHg

31. The patient’s physiological dead space is

a. 80 ml
b. 90 ml
c. 100 ml
d. 110 ml
e. 120 ml

32. The patient’s alveolar ventilation is

a. 4.0 L/min
b. 4.5 L/min
c. 5.0 L/min
d. 5.5 L/min
e. 6.0 L/min

33. To return the PCO2 value to normal, the patient would have to increase her alveolar ventilation to

a. 6.5 L/min
b. 7.0 L/min
c. 7.5 L/min
d. 8.0 L/min
e. 8.5 L/min

34. At the end of a quiet inspiration, intra-alveolar pressure is normally

a. –40 cmH2O
b. –4 cmH2O
c. 0 cmH2O
d. 14 cmH2O
e. 140 cmH2O

35. During the effort-independent portion of a forced vital capacity (FVC) maneuver, the expiratory flow rate

a. varies as a function of the interpleural pressure
b. is limited by compression of the airways
c. depends on the alveolar pressure
d. is maximal for that individual
e. is constant
f. two of the above are true

Answer Key

1. d
2. c
3. b
4. d
5. c
6. c
7. c
8. b
9. c
10. e
11. a
12. e
13. b
14. c
15. d
16. c
17. a
18. d
19. c
20. d
21. d
22. b
23. a
24. d
25. b
26. b
27. c
28. d
29. b
30. c
31. c
32. e
33. c
34. c
35. b