Eli5: How do bones and other organs know what shapes to grown into?
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Basically the cells in your body can communicate with one another and we call this “cell signalling” Your body is able to find the right balance of releasing signals to cells that need to grow faster or slower or for a different function altogether. This intricate system that your body has in place allows your organs to gain the shape it needs to carry out is function.
“ELI5 <one of the foremost cutting edge and complicated scientific questions known to humans>”
TLDR: dna is code that describes an organism.
Imagine you’re a cell and you have a huge book that serves as a blueprint to build an entire human body. Then one day you divide into 2 cells, so you give each new cell a copy of the blueprint book, but you specifically highlight all of the blueprints to make the upper body in cell 1’s book and you black out the lower body plans. You give the opposite to cell 2. So cell 1 now only really has the instructions for the upper body. But the biggest instruction in that whole half of the blueprint is to divide and give part a of the instructions to one cell and part b to the other cell.
Now the ‘upper body’ cell splits and gives copies of the blueprints that they have to the 2 new cells. One set of blueprints highlights the head and blacks out the torso/arms, while the other cell gets the inverse set of instructions.
So on and so on, every generation the cells keeps getting more and more specific instructions to read from the original book. Eventually you have cells that are just reading an individual chapter. Maybe a chapter that says ‘congratulations. You are the last cell that we need in this location to form the bone. Don’t divide any more, because if you do you will nudge out the lines of the bone and create a deformity.’ So that cell doesn’t divide.
It just lives there as a bone cell. In fact the next sentence in that chapter might read something like ‘collect as much calcium and phosphate as you can from the blood, and pile it around you as densely as you can.’ Now you have a bone cell, keeping that corner of your bone hard, and correctly shaped – at least in his own little corner of your body.
There are special genes called Hox genes that tell your cells where to grow
https://en.wikipedia.org/wiki/Hox_gene
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