Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Interstitial fluid are all hormones secreted into before entering the circulatory system.
Where are all hormones secreted into before entering the circulatory system?

The active transport of ions across the membrane causes an electrical gradient to build up across the plasma membrane.
The active transport of ions across the membrane causes an electrical gradient to build up across the what?

The cochlea and vestibul make up the inner ear.

The cochlea and vestibul make up what part of the ear?