The Role of Circulating and Local Hormones
Circulating Hormones
Circulating hormones are chemical messengers that travel through the bloodstream to reach their target tissues. Let's break down the key players and their roles:
1. Insulin
- Produced by: Beta cells in the pancreas
- Primary function: Blood glucose regulation
- Key actions:
- Promotes glucose uptake by cells
- Stimulates glycogen storage in liver and muscles
- Increases protein synthesis
- Promotes fat storage
Think of insulin as the "storage hormone" - it helps pack away nutrients for later use!
2. Glucagon
- Produced by: Alpha cells in the pancreas
- Primary function: Raises blood glucose levels
- Key actions:
- Stimulates glycogen breakdown
- Promotes gluconeogenesis (making new glucose)
- Increases fat breakdown
Insulin and glucagon work as antagonistic pairs - when one goes up, the other typically goes down.
3. Adrenaline (Epinephrine)
- Produced by: Adrenal medulla
- Primary functions during exercise:
- Increases heart rate
- Dilates airways
- Mobilizes energy stores
- Redirects blood flow to working muscles
During a 100m sprint, adrenaline helps prepare your body by:
- Increasing heart rate for better oxygen delivery
- Breaking down glycogen for quick energy
- Dilating airways for better breathing
