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Asked by aileenjcat to Colin, John, Kevin, Shikha, Triona on 18 Nov 2014. This question was also asked by Abbie.
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Kevin Motherway answered on 18 Nov 2014:
The really amazing part about life is that it is a self replicating molecule. All cells in your body contain the entire blueprint to make another you: We call it DNA! So when you cut yourself you’ve got platelet cells that help clot the blood and seal the wound in a scab. White blood cells arrive to kill off any infections that might have got in and to clean away any debris and reabsorb the nutrients that are lying around at the scene of the accident. The the skin cells and and muscle cells damaged start to replicate according to the DNA recipe and you generate more tissue to repair the damage, all under the seal of the scab. While this self replicating is going on mistakes can happen in transcribing the DNA and this is how cancers can happen, white blood cells will often spot the defective cells and wipe the out but if they become established a tumour can form: and this is now UV light burns on your skin from the sun can result in skin cancers.
Some tissue like nerves cannot be replaced, so that’s why nerve damage like spinal injuries DNA can be so permanent, but some nerves like the ones in your nose do constantly regenerate so this is a promising area of research to fix “permanently” damaged spinal nerves by transplanting.
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Shikha Sharma answered on 20 Nov 2014:
Hi Abbie and aileenjcat,
The Human Body is wonderful thing. When a cell is damaged the body try to repair or replace the cell to continue its normal functions. If a component of cell is damaged, there are a range of DNA repair mechanisms in the cell: non-homologous end-joining, homologous recombination, nucleotide excision repair, mismatch repair and a few other minor ones. Difficult terms 😀 😀
They all function in a different way but the idea is that “damaged” DNA is removed and then resynthesized. But the proteins are destroyed using protein degradation system. Small damage to membranes is not bothersome, but lots of membrane damage, leads to cell death. If a cell dies the body will remove it and replace it with another functioning cell, or fill the gap with connective tissue to provide structural support for the remaining cells. The goal of the repair process is to fill the gap caused by the damaged cells to regain structural continuity. Normal cells try to regenerate the damaged cells but this cannot always happen.
Stem cells are cells with the ability to transform (differentiate) into any specialized cell of the body, or characteristic cells of the same lineage. They are able to renew themselves through cell division even after long periods of inactivity and induced to form cells of tissues and organs with special functions. Some cells take days, other takes months or even years to repair themselves. Unfortunately, eyes and brain cells cannot repair themselves.
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