11.  Serum electrolyte concentrations are most often expressed as  
A.  mg %.
B.  mmHg.
C.  mg/dl.
D.  mEq/L.
E.  None of these choices is correct.

12.  The predominant extracellular anion is  
A.  protein.
B.  phosphate.
C.  bicarbonate.
D.  chloride.
E.  sodium.

13.  Where is the highest concentration of bicarbonate ion found?  
A.  plasma
B.  intracellular fluid
C.  interstitial fluid
D.  lymph

14.  Water moves back and forth across the plasma membrane by the process of  
A.  osmosis.
B.  filtration.
C.  facilitated diffusion.
D.  active transport.
E.  endocytosis.

15.  The cation that plays a major role in determining the osmotic pressure of the plasma is  
A.  sodium.
B.  potassium.
C.  chloride.
D.  phosphate.
E.  hydrogen ion.

16.  The major route of excretion for sodium ions (under normal conditions) is the  
A.  skin.
B.  kidney.
C.  GI tract.
D.  adrenal cortex.
E.  sweat.

17.  When aldosterone is absent, sodium reabsorption in the nephron is  
A.  greatly increased.
B.  greatly decreased.
C.  unchanged.

18.  As the rate of sweat production increases, the amount of sodium lost in the urine  
A.  increases.
B.  decreases.
C.  remains the same.

19.  Receptors sensitive to changes in the osmolality of extracellular fluid are the  
A.  baroreceptors.
B.  chemoreceptors.
C.  osmoreceptors.
D.  pressoreceptors.
E.  proprioreceptors.

20.  Renin is released by the  
A.  lungs.
B.  kidney.
C.  spleen.
D.  liver.
E.  pancreas.