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?
Actually just learned this last semester!
The ELI5 version is that the hormone “adrenaline” flows through your bloodstream (endocrine system) and attaches to receptors on the cells of your heart muscles (could be wrong on the exact location) and causes a change in the cells and tells your heart to beat faster, which is why you feel more flush and why sometimes you can feel your heart beating through your chest.
The endocrine system is surprisingly fast, and rightfully so, because if you’re in a life or death situation you need that adrenaline NOW. That’s why it’s called the “fight or flight” response, sometimes.
A more in depth way of explaining why they happen so fast also has to do with the amount of change that occurs in the cell due to a cascading event starting from one molecule, which turns on a bunch of other proteins, and so on and so forth until one molecule essentially turns on dozens or hundreds of other molecules responsible during the adrenaline response.
Some of my thoughts could be wrong, someone will have to correct me as i am pulling from memory and on mobile.
Edit: “feeling” to “response”
Edit: Some others have added some additional, useful details. Credit where credit is due:
had some ELI5 and some non-ELI5 responses that add information I left out or did not know. Thanks!
Your brain also contains neurotransmitters that are stimulating. SO when you are frightened nerve cells will release norepinephrine in the brain which increases arousal, vigilance, etc. This would be the initial sensation at fright followed very quickly by the release of adrenaline which stimulates heart rate, etc.
Too comment is the most accurate. But to help you understand why everything is so fast realize this: your body is only a couple feet long; your blood is traveling around 3mph.
Your heart is one of the hardest working muscles in your body for a reason. Your blood travels fast and your lymph travels nearly as fast(?)
So adrenaline is a neuro-hormone which means it’s release can be triggered by the electrical impulses from your brain. This makes the release of it suuuuper quick and it also happens to come from your adrenal glands above the kidneys, and the kidneys are getting 20-25% of all your blood flow which makes it circulate through the body super fast. The receptors for it are all on the surfaces of cells so it’s recognized pretty quickly too and the response is multiplied over a few stages inside the cell which gives it a quick and robust response. It’s basically just a speedy process overall
It only takes a couple of seconds for adrenaline released from your kidneys to reach the rest of your body , so as soon as it reaches that tissue it will have an effect , i.e.braised heart rate , resp rate etx