Why does our body age over time?

Answer 1

It depends on what you mean by "aging." I assume you mean "why does our body get old and start wearing out." One of the theories is called the telomere hypothesis. Telomeres are long pieces of DNA that do not code for genes that sit at the ends of chromosomes to protect them. The most vulnerable part of DNA is the very ends of the molecule- there are lots of enzymes floating around in the cell that degrade DNA from the ends, called exonucleases. One aspect of DNA replication is that due to the ways the replication enzymes work, it is impossible for you to replicate the very tips of the telomeres. So after one division, the telomere is a little bit shorter. After another division, it gets even shorter. These small deletions accumulate as you develop from a single cell into a large multicellular organism, where perhaps hundreds of thousands of cellular divisions have taken place.

Some cells in the body have a special enzyme called telomerase that repairs that damage. Germ cells (those that produce sperm and eggs), stem cells, and embryonic cells all have a lot of telomerase, so they largely repair the damage. This is good, because it's the job of those cells to continually divide, and you don't want to be messing up the DNA of their daughter cells. The somatic cells in our body (liver, skin, intestinal lining, etc), which make up the bulk of us, don't have a lot of telomerase, even though they go through cell divisions as well. As a result, their telomeres are going to get shorter and shorter as you get older, to the point where you start risking damage to DNA that actually codes for genes. As that happens, we "senesce," and things start to wear out.

People have done experiments with telomerase to try to slow down senescence. Cancer cells, which divide rapidly and uncontrollably, express a lot of telomerase, and as a result their telomeres don't shorten- that's thought to be one of the reasons why tumors grow. If their telomeres were getting shorter, the tumor would eventually kill itself. And when you express mutant, nonfunctional telomerase in cancer cells in a petri dish, the cells die after a while.

But really, this is still an active area of research.

Answer 2

Organs just get old like any other thing in the world. However a living organism will never die of old age. This may seem weird but actually the only way for a living organism to die is through illness. Old age makes the organs more prone to illness, and cells malfunction and stuff, thus failure to the organs. They don't just get old and die, there is always a reason.

Answer 3

Because perfection is boring.

Mechanically there is a chain on the DNA that reduces every time a cell replicates. The human limit is 52 (they found 53 in one family) this is known as the hayflick limit.

Primary aging is just getting older, secondary aging is caused by chemicals / cigarette smoke / sun exposure.

Answer 4

Well. Time is time. It is the type of measurement we use to measure the distance of the future, or past. We grow, which is over TIME. We grow as in the years. We age. If that makes sence. Why do we grow? Growing is a stage of getting older and aging.

Answer 5

Everything has a halflife.

Think of humans as a chemical reaction. At the halflife (~27 years old), the body is finally unable to produce more new cells than are dying off.

It's a battle of new vs old cells. Too few new & too many old = body can't take care of itself like it used to. After awhile, it fades away.

Answer 6

Just like machinery our body parts wear out and finally fail.

Answer 7

everything in this world ages over time, the longer it's here, the older and more worn it gets.....that goes for humans too.

Answer 8

i dont really know but it might be because of all the things that u have learned and went throgh in your life....and all the fun that u have had finally catches up to u

Answer 9

because of sin and imperfection... the first humans were created perfect with no intention of dying but satan turned them against God so that God's blessings left them... they inherited satans attititude and so God took eternal life from them

think of it like a baking tin... when it gets dented it can only produce cakes with dents. the human would eventually grow old, get sick and then die... Sad fact :-(

Answer 10

because the cells get corrupted with time and dont reproduce, and genes set are dying rate.