Sometimes we feel thirsty and sometimes, hungry. How does our brain know that apart?
In: Biology
Humans have special receptors called osmoreceptors in our brains that watch for the amount of sodium in the blood. When the amount gets too high it means the body needs to have more water and the osmoreceptors release a hormone called arginine vasopressin. AVP causes the thirst center in our brain to trigger. It also signals our kidneys to hold onto more water in the mean time to keep sodium levels in check.
Food on the other hand is based on blood sugar levels. When blood sugar levels get low (i.e. when we’ve finished digesting a meal and used up some of the energy), a hormone called ghrelin gets released. This causes the smooth muscle tissue of our digestive system to get to work and absorb more energy. If there’s nothing left in the stomach, you get a growling stomach and your brain triggers that it’s time to eat.
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