Adrenaline causes the pupils to dilate (widen).
This dilation is a key component of the "fight or flight" response. When the body perceives a threat or experiences stress, the adrenal glands release adrenaline (also known as epinephrine) into the bloodstream. This hormone triggers several physiological changes designed to prepare the body for action.
Here's a breakdown of how adrenaline affects the pupils:
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Mechanism: Adrenaline binds to alpha-adrenergic receptors in the iris dilator muscle. This binding causes the muscle to contract, pulling the iris outward and widening the pupil.
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Purpose: Dilated pupils allow more light to enter the eye, enhancing vision. This enhanced vision can improve awareness of the surroundings and potentially aid in responding to the perceived threat. The dilation allows for better peripheral vision and allows the individual to gather more information from their environment.
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Fight or Flight Response: Pupil dilation is just one aspect of the fight or flight response. Other effects of adrenaline include increased heart rate, increased blood pressure, increased breathing rate, and redirection of blood flow to the muscles.
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Other factors: It's important to note that other factors besides adrenaline can cause pupil dilation, including darkness, certain medications, and medical conditions. So, dilated pupils alone don't necessarily indicate adrenaline release.
In summary, adrenaline causes pupil dilation as part of the body's natural "fight or flight" response, enhancing vision in potentially dangerous or stressful situations.
