What makes you age? Various reasons for aging in the city

Everyone will feel scared when hearing the word "aging", especially girls. Once aging occurs, in addition to aging with age, the skin becomes rough, dry, and dehydrated. The face will be covered with terrible wrinkles, the eyes will become dull, the breasts will sag, and you will no longer have a beautiful face and a slim figure. People will always grow old. What is the cause of aging?

What is the cause of aging? Aging does not actually begin in middle age. According to experts, aging begins in adolescence, but the aging process is quite long, so only after the age of 25 will you feel aging in all aspects. In fact, aging is not just the aging of the skin, but more importantly, all the organs in the body are aging.

Regarding the mechanism of aging, scientists say there is a hypothesis. But so far, no hypothesis can independently and completely explain the fundamental cause of aging. The ones with relatively sufficient evidence include the "molecular cross-linking" theory and the "error-causing disaster" theory, which are closely related to genetic genes, and the intercellular substance theory that aging is caused by excessive accumulation of intercellular collagen. Intercellular substances refer to substances produced by cells and secreted into cells or between cells. Such as hyaluronic acid, collagen, etc. Hyaluronic acid is a macromolecular substance that plays an important role in maintaining moisture in tissues. During adolescence, there is more hyaluronic acid, and the skin is moisturized and plump. But with aging, hyaluronic acid decreases and is replaced by collagen. Collagen not only lacks elasticity, but is also not easily decomposed, so it is difficult for nutrients to enter cells and for cell waste to be eliminated, resulting in low cell metabolism, which ultimately leads to cell aging. Especially when collagen appears between capillaries, lymphatic vessels and cells, aging will appear quickly. According to biologist Dr. Luo Xin, the water content in cells of people over 65 years old is only about 80% of that in young people. Arterial sclerosis is caused by the above phenomenon in the arterial wall. When blood vessels harden and blood flow is obstructed, it is bound to cause serious functional disorders of various organs. The elderly are often accompanied by arteriosclerosis.

In addition, when the immune function is abnormal and aging occurs, an intercellular substance, amyloid protein AMYLOID, will appear and can also cause functional disorders. Patients will develop aging symptoms such as gray hair, hair loss, and skin aging when they are 10 to 20 years old, and often have complications such as adult diseases such as arteriosclerosis and diabetes. They die at around 45 years old. The cause of premature aging is believed to be that the hyaluronic acid in the cells is excreted at an abnormally fast rate and therefore cannot function fully, leading to cell aging. The lifespan of mammals is fixed, generally equivalent to 5 to 10 times the time it takes the animal to reach maturity. If humans reach sexual maturity between the ages of 15 and 20, then human life expectancy should be between 75 and 200 years.

Brain weight is related to life expectancy. There are legends of humans living to 152 years old, but there is no reliable birth certificate. In Japan, the life expectancy with a birth certificate has not exceeded 124 years. The only person still alive is Shigechiyo Izumi, a native of Kagoshima Prefecture, who was born on June 9, 1965 and is now 123 years old. Genes and lifespan are closely related. An animal's metabolic rate and ability to repair DNA damage are both related to its lifespan. Others believe that life expectancy is related to brain weight. Looking at the relationship between the lifespan and the ratio of brain weight to body weight of 85 species of animals from mice to elephants, there is a very obvious correlation between the two: animals with larger brain weights also have longer lifespans. Human life goes through various stages of development, maturity, and aging, and follows certain regularities. However, since the human body is affected by harmful factors to different degrees, the aging process can be different between people. This is individual difference. Especially in the later stages of life, these individual differences become more pronounced, making it difficult to determine lifespan.

In biological research, cell culture is an important basic method. That is to say, the somatic cells of an individual organism are taken out and cultured and studied in containers such as test tubes or petri dishes. Initially, people believed that as long as the conditions were suitable, cells cultured in vitro could reproduce indefinitely. However, in 1961, Hayflick and others proposed that the reproduction of cells cultured in vitro was limited. They observed that after fibroblasts were cultured, the number of fibroblasts that were originally in the dormant phase suddenly increased, but soon the proliferation rate decreased and finally reached a stagnant state. At this point the cell volume increases and division stops. They believe this phenomenon is a manifestation of longevity at the cellular level. At the time, most scholars were skeptical of their views. However, many experimental results have now confirmed that Hayflick's concept of the maximum lifespan of cells is correct for most mammals.

When fibroblasts are obtained from fetal lungs, the number of passages required to double the cell number is 50 to 70. If fibroblasts are taken from adults and cultured, the number of cell generations decreases as the donor's age increases, and can generally be passed on average 10 to 30 generations. By taking advantage of the fact that the ability of cultured cells to reproduce is inversely proportional to the age of the donor, people can infer the age of an individual by measuring the number of fibroblast passages in a person of unknown age. The results of the investigation using this method proved that the longest lifespan of various animals is proportional to the number of cell doublings and generations of the same species, that is, the animal with the longest lifespan also has the largest number of cell doublings and generations. For example, the longest lifespan of mice is 3.5 years, and the number of passages of fibroblasts is only 14 to 28, while the number of passages of fibroblasts in human embryos is 40 to 60. The number of fibroblast passages in children with hereditary progeria is only 2 to 10. If these phenomena are analyzed in depth, it may be possible to determine the mechanisms of aging and longevity. It has now been proven that animals with strong repair capabilities have long cell and individual lifespans after genetic gene damage. If chimpanzees' genetic damage repair rate is only half that of humans, then their lifespan will also be exactly half that of humans. All these suggest that aging and life span are closely related to genetic gene structure.

Everyone hopes to live a long life, but there are always many people who die early due to various reasons. Therefore, there are relatively few people who live to a ripe old age. Why do people age and what are the causes of aging? Experts have introduced various aspects related to aging. From the above introduction, we understand that human aging begins in adolescence.