What ions do NOT cross the blood-brain barrier?
A) H+ and Ca2+
B) H+ and HCO3-
C) HCO3- and Cl-
D) Na+ and Cl-
E) Na+ and Ca2+

Question

What ions do NOT cross the blood-brain barrier?
A) ​H+ and Ca2+
B) ​H+ and HCO3-
C) ​HCO3- and Cl-
D) ​Na+ and Cl-
E) ​Na+ and Ca2+

Quizplus · Accepted Answer

H+ and HCO3- do not cross the blood-brain barrier because they are charged ions. The blood-brain barrier is a protective layer of cells that surrounds the brain and spinal cord. It helps to protect the brain from harmful substances in the blood. Charged ions cannot cross the blood-brain barrier because they are repelled by the electrical charge of the cells.

What Ions Do NOT Cross the Blood-Brain Barrier