Quizbowl science/Biology/Epinephrine
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Epinephrine or adrenaline is an amino acid derivative hormone (polar). It is released from the adrenal medulla.
Functions[edit | edit source]
- Acts on liver cells to increase blood glucose by:
- increasing glycogen breakdown and
- increasing gluconeogenesis.
- Acts on muscle cells to make ATP by
- increasing glycogen breakdown
- increasing glycolysis
- increasing beta-oxidation (breaking down fatty acids to get energy)
Basically, the liver makes glucose, and the muscle breaks down that glucose, so ATP is available for fight-flight.
Mechanism[edit | edit source]
Epinephrine binds a G-protein coupled receptor, activating adenylate cyclase, which produces cAMP from ATP. This causes protein kinase A to become more active. PKA phosphorylates:
- makes glycogen synthase less active
- activates phosphorylase kinase -- makes glycogen phosphorylase more active (involved in glycogen breakdown -- glycogenolysis)