system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you are in the hospital and get an IV how does your body "taste" what's in the IV?

For example, when you get a saline IV and you can "taste" the sodium while the IV drips. Just curious on how this happens internally in the body.
gpt
If you increase the sodium concentration in your blood, all the (relatively thin) mucosal membranes in your nose and mouth can pick up on that, as that blood courses through them in the course of regular circulation. At the end of the day, all that taste is is electric signals which fire when a molecule binds with a receptor, and a lot of the binding is based on simple stuff like charge and molecular shape. If you think about it, it's very evolutionarily beneficial for the body to be able to inspect the chemical makeup of its blood.