How do hormone responses occur so rapidly? When people are frightened/surprised, they can almost immediately feel a rush of adrenaline and heart rates rise, faces flush, etc. How do hormones reach appropriate organs so quickly? Why isn’t there more of a delay for the hormones to travel?

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How do hormone responses occur so rapidly? When people are frightened/surprised, they can almost immediately feel a rush of adrenaline and heart rates rise, faces flush, etc. How do hormones reach appropriate organs so quickly? Why isn’t there more of a delay for the hormones to travel?

In: Biology

12 Answers

Anonymous 0 Comments

I think you are confusing the neurotransmitters epinephrine/ norepinephrine (aka adrenaline/ noradrenaline) with the hormone cortisol. The immediate response is so fast because norepinephrine works entirely in the brain and signals near instantly to affect your activity, heart rate, and breathing. The signal travels down the spine to the adrenal glands where epinephrine is released into the blood stream causing blood vessels to constrict, glucose to be used, and muscles to respond. After a couple hours, the hormone cortisol is secreted into the blood stream from the adrenal gland to maintain this burst if needed.

Adrenaline and noradrenaline are both neurotransmitters (think fast acting) that have hormone properties. Most hormones act much slower because they travel in the bloodstream, whereas these two function together in the brain with electrical signaling speed.

Fun fact: tyrosine the dietary amino acid is converted to dopamine (pleasure molecule), which is converted to noradrenaline, which is then converted to adrenaline…

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