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Hormones and blood sugar

Hormones are chemical signals in the blood. Insulin from the pancreas lowers blood sugar by making cells take up glucose. Glucagon from the same gland raises blood sugar by making the liver release glucose. The two act in opposite directions, and that is negative feedback: a deviation sets off a response that counteracts the deviation. Adrenaline prepares the body for effort and can also raise blood sugar. The nervous system is fast and hits one synapse. The hormone system is slower and hits every cell that has the right receptor.

insulin↓blood sugar,glucagon↑blood sugar\text{insulin} \downarrow \text{blood sugar},\quad \text{glucagon} \uparrow \text{blood sugar}opposite effects

Symbols

insulininsulinlowers
glucagonglucagonraises

Example

High blood sugar gives more insulin, and the sugar falls.

Low blood sugar gives more glucagon, and the sugar rises.

Insulin and glucagon both come from the pancreas, but from different cells.
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Part of Biology 2: The nervous system and hormones.