Why dont we go from, for example, 3 billion cells to 6 billion. Say the body stops, or slows, how does the body m ow when to do that?
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Cells do not duplicate exponentially. Cells divide when they get damaged, making a new healthy cell, and the damaged cell dies off (via the lysosomes in the cell)
Inside each cell is a chemical “chain” called a telomerase chain, and every time a cell divides, one “rung” of this chain is broken/not copied over. When the telomerase chain is gone, the cell will no longer divide when damaged, which is why we eventually grow old and die: our cells are pre-programmed to only have a certain lifespan, they do not divide forever
Multiple functions prevent this from happening. Here are some examples:
Most cells do not divide without being told to do so by the body’s signalling systems. The cells of the body need to divide at different rates depending on wear and tear of the tissues they are part of (cells in the outer layers of the skin for exemple need to divide faster than nerve cells in the brain).
To survive, healthy cells require signals from the body that tells them they are needed. The body will only provide signals to keep a sufficient number of cells alive, which means that ”surplus” cells that do not receive these signals will neatly pack up their contents for ”recycling” and die.
Damaged cells will in some cases sense that they no longer function correctly, and neatly pack up their contents and die (this is called apoptosis and is less harmful than cells rupturing chaotically and damaging their surroundings). The immune system also has cells that check other cells for damage or infection and send ”kill” signals if they find something amiss.
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