The purpose of the blood-brain barrier is to:
a. protect the brain from accidental impacts.
b. block the entrance of some substances into the brain.
c. block neurotransmitters from being released.
d. provide a cushion for the brain.
Question 2
For Na+ ions, _______________ pushes them into a cell.
a. electrostatic pressure
b. diffusion
c. neither electrostatic pressure or diffusion
d. both electrostatic pressure and diffusion