What signals the body to start puberty? Is it just a pattern of chemical reactions that starts changing the body around the same time? is there something that signals the body to start changing at a particular point?
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>Is it just a pattern of chemical reactions that starts changing the body around the same time?
It’s just that, although it doesn’t really “know” when to start. Growing up is a continuous process we take part of since the second we’re born. Our DNA encodes information about what each part is supposed to do. The endocrine system is constantly monitoring the body and secretes hormones in response to different signals. At some point, you will have grown enough for puberty to start, and that’s an instruction encoded in your genetics the same way it encodes your eye color or nose shape. Think of it as part of a very long process that only ends around the time you’re 25-ish.
There is a small part of your brain called the Hypothalamus.
The hypothalamus does a lot of things, but related to puberty it basically does a checklist if the body is big enough and have large enough fat reserves that it’s ready to become sexually active.
Once the body is going “We’re ready to start” the hypothalamus starts to emit a hormone (gonadotropin) that trigger the sex organs to mature (testes, ovaries). These organs in turn start to emit their own hormones when they’ve grown enough, and when those hormone levels are high enough it triggers further mental and physical development.
It’s basically a staging list, where each step triggers the next as it becomes functional.
Really good question. I don’t think the science guys have worked out exactly how the old biological clock is set . They know some genes that cause early and late puberty and there’s some common sense issue like if you’re starving puberty gets delayed vs starting a little early with obesity.
In terms of the single thing that starts off puberty, no one knows for sure.
We know that the hypothalamus is important for some hormones that are released, but this is really what drives puberty. In the car analogy, we don’t know for sure what actually starts the motor.
One of the leading theories is that you counterintuitively become *more resistant* to sex hormones. Normally, you have a small amount of them, and those are measured by a protein called “kisspeptin.” When it loses sensitivity, it goes from thinking that there is the perfect amount of sex hormone to almost none. It starts yelling at other cells (including the hypothalamus) to try to correct that problem. Ultimately, this makes the body go from perfectly happy with a small amount of sex hormone to needing a lot of it.
For further reading (ELIcollege), see: https://endocrinenews.endocrine.org/kisspeptin-switching-on-puberty/
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