I have a bio test tomorrow on the endocrine and nervous systems, and i have a few questions. 1) Are the endocrine glands and the exocrine glands both part of the endocrine system? 2) For exocrine glands, do the glands just secrete the hormones through ducts or tubes, or do they actually use these hormones (e.g. tear and sweat glands)? 3) How does ADH regulate Na levels if it only controls water permeability? (if there's more water in the blood, would the Na conc. just decrease?) 4) How does depolarization work, that is, is there a Na/K pump after every K and Na "door"? (i.e. the impulse travels like so: K(open)Na(closed)-->K(closed)Na (open) --> Na/K pump....and this repeats) Test is tommorrow - thanks.