3Which sleep stage is the transitional stage between drowsiness and sleep?

An optimal PA cranium projection demonstrates all the following except

a. equal distance from the lateral orbital margins to the lateral cranial cortices on both sides are equal. b. anterior clinoids and dorsum sellae seen inferior to the ethmoid sinuses. c. petrous ridges superimposing the supraorbital margins. d. internal acoustic meatus visualized through the center of the orbits.

A measure of the concentration or amount of substances dissolved in urine is ________.

Fill in the blank(s) with the appropriate word(s).