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

Those are not purely hormonal. There are nerves in your heart and other organs and the nervous system has ways to regulate the rhythm of your heart, your breathing rate, oxygen and blood supply tp your organs, etc.

See here:

https://en.wikipedia.org/wiki/Autonomic_nervous_system#Sympathetic_nervous_system

>**Diverts blood flow away from the gastro-intestinal (GI) tract and skin via vasoconstriction**
*You don`t need those when you are in panic and it also reduces bleeding from minor cuts*

>**Blood flow to skeletal muscles and the lungs is enhanced** (by as much as 1200% in the case of skeletal muscles)
*Run faster*

>Dilates bronchioles of the lung through circulating epinephrine, which **allows for greater alveolar oxygen exchange**
*Get more oxygen*

>**Increases heart rate and the contractility of cardiac cells (myocytes), thereby providing a mechanism for enhanced blood flow to skeletal muscles**
*Run, Forest, run!*

>Dilates pupils and relaxes the ciliary muscle to the lens, allowing more light to enter the eye and enhances far vision

>Provides vasodilation for the coronary vessels of the heart

And here:

https://en.wikipedia.org/wiki/Autonomic_nervous_system#Parasympathetic_nervous_system

>Constricting the bronchiolar diameter **when the need for oxygen has diminished**

>Dedicated cardiac branches of the vagus and thoracic spinal accessory nerves **impart parasympathetic control of the heart (myocardium)**

Or see this paper about the heart nervous system in heart transplant patients:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5210323/

>Furthermore, the exercise capacity in denervated HTx recipients seems to be diminished because **denervated hearts must rely on circulating, rather than cardiac, catecholamines (CAT) release to adapt to the increased needs of exercise,** although this adaptation is insufficient to reach normal heart rate (HR) and contractility.21 Early cardiac denervation in HTx recipients leads to the loss of the normal nocturnal decline in blood pressure.16 **It also causes a higher than normal HR at rest, and, in response to exercise, the HR increases more slowly than normal to reach a lower maximal HR, which descends during recovery from exercise at a slower than normal rate.** In addition, cardiac denervation causes an abnormal cardiac output (CO) response to exercise.

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