Which of the Following is (Are)true of Na⁺

Question

Which of the following is (are)true of Na⁺?
A) Is the chief extracellular anion
B) Helps regulate extracellular volume
C) Is regulated by ADH
D) All of the above

Accepted Answer

Na⁺ is the chief extracellular cation (not anion) and it is regulated by aldosterone, not ADH. However, Na⁺ does help regulate extracellular volume by controlling water movement through osmosis.