General and Cell Physiology

 

  Use the diagram below for the next 4 questions.  Choices may be used more than once.

 

 

 

 

 

 

 

 

 

 

 

 

 

  

1. 

 A 43-year-old female with a history of severe diarrhea was admitted to the ER after fainting at the supermarket.  Physical exam revealed decreased sking turgor.  The patients volume and osmolarity in the extracellular (ECF) and intracellular (ICF) fluid compartments is best represented by graph _______.      Correct Answer  explanation of answer

A.  A

B.  B 

C.  C

D.  D 

 

E.  E 

 

F.  F 

 

 

 

 

 

 

 

2. 

 A 23-year-old victim of a knife attack is admitted to the emergency department.  The EMT reported significant blood loss at the scene.  Blood pressure is found to be 90/60 with a weak pulse of 95 bpm.  The patients volume and osmolarity in the extracellular (ECF) and intracellular (ICF) fluid compartments is best represented by graph _______.      Correct Answer  explanation of answer

A.  A

B.  B 

C.  C

D.  D 

 

E.  E 

 

F.  F 

 

 

 

 

 

 

 

 

 

3. 

 A 55-year-old was taken to the emergency department of a local hospital after having a grand mal seizure.  He had no history of epilepsy, but his wife reported that he had been diagnosed with oat cell carcinoma of the lung and that he had become increasingly lethargic and confused for the past few weeks.  His laboratory values were:

      Plasma Na+ = 108 mEq/L (normal = 140)

      Plasma osmolarity = 200 mOsm/L (normal = 290)

      Urine osmolarity = 1000 mOsm/L

 

The patients volume and osmolarity in the extracellular (ECF) and intracellular (ICF) fluid compartments is best represented by graph _______.      Correct Answer  explanation of answer

A.  A

B.  B 

C.  C

D.  D 

 

E.  E 

 

F.  F 

 

 

 

 

 

 

 

 

 

 

Explanations:

Imbalances in body fluid volumes are caused by abnormal intake and loss.  As shown below, the initial disturbance shows up in the plasma which, along with interstitial fluid, is part of the extracellular fluid.  Fluid will move into or out of the intercellular space ONLY if there is a water gradient; i.e., difference osmotic pressure between the ECF and ICF.

 

1.  Choice A is correct.  Diarrhea causes a loss of isotonic fluid from the GI tract.  Since there is no change in osmotic pressure of the ECF, there is no shift of fluid from the ICF to the ECF.

2.  Choice A is again correct.  for the same reasons; i.e., blood loss is loss of isosmotic fluid, the the ECF compartment shrinks with no shift of fluid out of the ICF.

3.  Choice F is correct. In this case, the cancer cells are secreting ADH, causing what is termed, "syndrome of inappropriate andidiuretic hormone" or SIADH.  The pituitary stops secreting ADH when osmolarity decreases, but the cancer cells do not.  The urine becomes very concentrated and the patient becomes hypotonic, with expansion of both ECF and ICF.