Epinephrine Triggers Physiological Changes for Fight-or-Flight Responses
Definition
Epinephrine
A hormone and neurotransmitter, also known as adrenaline, produced by the adrenal glands that prepares the body for "fight or flight" responses during stress or excitement.
- Imagine you’re about to run a race. Your heart races, your breathing deepens, and your muscles feel ready to explode with energy.
- This transformation is driven by epinephrine, also known as adrenaline.
The Fight-or-Flight Response Prepares the Body for Action
- The fight-or-flight response is an evolutionary survival mechanism that enables an organism to react quickly to perceived danger or stress.
- It is triggered by the sympathetic nervous system, which stimulates the adrenal medulla to secrete epinephrine into the bloodstream.
- If the body chooses to fight, energy is mobilized for combat.
- If the body chooses to flee, energy is redirected to support escape.
- Imagine you are suddenly confronted by a wild animal.
- Your heart starts racing, your breathing quickens, and you feel a sudden surge of energy—this is the effect of epinephrine preparing you for action.
What Triggers Epinephrine Release?
- Detection of a Threat or Opportunity: The brain detects a threat or opportunity.
- Signal to the Hypothalamus: The brain sends a distress signal to the hypothalamus, the brain’s command center for hormonal regulation.
- Activation of the Adrenal Glands: The hypothalamus sends nerve signals to the adrenal medulla, triggering the release of epinephrine into the bloodstream.
Definition
Adrenal gland
Small glands located above the kidneys responsible for producing hormones, including epinephrine.
Epinephrine acts quickly, preparing the body for action within seconds.
How Epinephrine Prepares the Body
1. Increases Oxygen and Glucose Supply
- Bronchodilation: Epinephrine relaxes the smooth muscles in the airways, widening the bronchi and bronchioles. This allows more air to enter the lungs, increasing oxygen intake.
- Increased Ventilation Rate: The hormone stimulates the respiratory centers in the brainstem, causing faster and deeper breathing.
- Glycogen Breakdown: In the liver and muscles, epinephrine activates enzymes that break down glycogen into glucose, providing a rapid energy source for muscle cells.
- Imagine sprinting up a hill.
- Your muscles need a quick burst of energy, which is supplied by the glucose released into your bloodstream.
