**A substance produced in one part of the body that causes action in another.** The definition of hormone: Substances produced in one part of the body that cause action in another. Hormones are only similar by definition. It's a functional definition, not a reflection of anything about them physically or chemically. They are very different from one-another. # Example Hormones - [[Insulin]] is a hormone made in the pancreases that causes your [[blood sugar]] to change - [[Testosterone]] is the hormone of desire, amongst other things - [[Noradrenaline]] and [[Adrenaline]] are hormones that do basically the same thing as each other - [[Dopamine]] is a hormone that causes motivation - [[Serotonin]] - [[Vitamin D]] is actually a hormone **** ## Source - [[The Body (book)]] - [[Huberman Labs]] - [[Simple Science Fitness]] ## Related - [[Pheromones and Hormones]] - [[Adrenaline]] - [[Dopamine]] - [[Noradrenaline]]