细胞再生时间表:身体部分需要多长时间才能再生

细胞再生是显而易见的事实，在我们的一生中，我们:


每20年换一颗心脏

每十年换一次骨头

每3-6年换一次头发

每6-10个月换一次新指甲

每4个月产生新的红细胞

每5个月换一个肝脏

一个新的外层皮肤每个月

每三周换一次肺

每两周换一次味蕾

每2-3天换一次胃粘膜

　

Cell Regeneration: A Matter of Life and Death
By Ty Bollinger
August 14, 2017

You may have heard it said that the human body completely regenerates itself every 7-10 years – replacing all of the old, worn out cells with brand spanking new ones. Like many popular myths, this one is only partially true. Many systems of the body (but not all of them) indeed function on regenerative cycles that fall within this time span. This means that, for the most part, we really do get entirely new bodies every decade or so… pretty exciting, right?

This important process is called cellular or cell regeneration. It functions as the means by which our bodies stay alive and continue forging on. It helps us to grow and develop in our younger years, and avoid premature aging and death in our older years.

Cell Regeneration Timeline: How Long It Takes for Body Parts to Regenerate
Cellular regeneration is evident in the fact that, throughout our lives, we get:

a new heart every 20 years
new bones every decade
new hair every 3-6 years
new nails every 6-10 months
new red blood cells every 4 months
a new liver every 5 months
a new outer layer of skin every month
new lungs every three weeks
new taste buds every two weeks
new stomach lining every 2-3 days
In a perfect world, these amazing regenerative cycles would keep us all in tip-top, youthful shape forever. But we don’t live in a perfect world: our bodies eventually age, fall apart, and die, as I’m sure you well know.

I realize it’s somewhat of a morbid subject, but it’s the sobering reality that we all face. It’s one that, apart from a concerted effort to stave it off for as long as possible through life-giving diet and lifestyle habits, is going to rear its ugly head sooner or later.

And that’s the kicker: there are ways to help support your cellular system and its regenerative cycles to keep them functioning at their best. Cell regeneration is something that’s programmed in our DNA. The glitches and abnormalities that keep the cells that are supposed to die, alive (and conversely, that terminate cells that are meant to live), can be corrected with precise intervention.

Apoptosis: When Cell Death Is a Good Thing
Here’s one of the things you need to know about this that most people don’t: Programmed cell death, also known as apoptosis, is a completely normal and necessary function of human life.

There are many billions of cells that make up our bodies, and when we experience an injury, are exposed to toxins, or become stressed, some of these cells end up becoming damaged.

Rather than replicate this damage, these damaged cells will either repair themselves or “commit suicide.” This is in order to protect the rest of the body (including other healthy cells) from assuming their flaws. Apoptosis can also occur in cells that are only needed for a certain length of time; the body cleaning them up after their task at hand is properly completed.

“Cells die either because they are harmful or because it takes less energy to kill them than to maintain them,” says H. Robert Horvitz, an expert on apoptosis from the Massachusetts Institute of Technology (MIT).2 “[I]t gets rid of cells that are not needed, in the way or potentially dangerous to the rest of the organism.”

One way of thinking about apoptosis is that it’s the body’s way of weeding its own garden.

As new cells are created in response to the intake of nutrients, these cells divide and create even more new cells. This jumpstarts the process of organ regeneration and energy creation – the fruitful “blooms” of the body in all of its glory. Rogue and excess cells also appear, and these “weeds” have to be removed or else they get in the way and cause problems.

Perhaps an even better analogy is clay formation, which Horitz describes like this:

[B]uilding a complex organism like a human being is like creating an intricate sculpture. Cell division forms the clay, whereas cell death sculpts the clay into the desired form. Consider human hands, which start out as paddlelike structures. Fingers develop in the paddles, but then the cells in the tissue between the fingers must die for a proper hand to form.”

Keep in mind that apoptosis is the very same process that cancer cells are supposed to undergo so as not to develop into full-blown tumors. In the event that they fail to self-destruct, for whatever reason, cancer cells take on the properties of healthy cells. They begin dividing, multiplying, and spreading to produce the potentially life-threatening condition we know clinically as a cancer diagnosis.

This is what cancer is, after all: a conglomeration of “zombie” cells that grows so strong that it creates its own competing organism within the body. Some of us are all too familiar with how disastrous this process can be, having lost our loved ones to this malignant progression.

Senescence: A Major Roadblock to Healthy Cell Regeneration
On the other hand, there’s another type of malignant cell that doesn’t necessarily go rogue and start replicating itself like cancer cells do. It doesn’t die or commit suicide, either, but simply lives on in static perpetuity alongside healthy cells as they go about their business. We call these senescent cells, and they result from constant exposure to stress and other damage, both endogenously and exogenously (meaning from both external sources and those within the body).3

Senescent cells are basically “zombie” cells that don’t serve any useful purpose and are programmed to die, but for whatever reason refuse to do so. They become toxic as a result, building up inside the body and causing all sorts of problems.

Besides functioning as catalysts for the growth and spread of cancer cells,4 senescent cells are known to:

Inhibit nutrient metabolism
Promote weight gain (fat, not muscle)
Suppress the immune system
Damage blood sugar balance
Impair memory (while contributing to dementia)
Accelerate the aging process
Although they don’t replicate like cancer cells do, senescent cells may, in fact, be worse. They fuel an inflammatory response throughout the body that can create more cancer cells. It’s a vicious feedback loop where the one seems to cause the other, followed by the other in turn causing the one. In other words, damaged cells go senescent to avoid becoming cancerous, but in the process they end up spurring on the proliferation of cancer cells.

4 Compounds That Target Senescent Cells & Help Slow Down Aging
So what’s a person to do? While aging may be unavoidable, there are ways you can help ease its progression and age with grace while enjoying a higher quality of life. As the popular expression goes, “prevention is the best medicine.” In this case, stopping cells from going senescent in the first place. The next option is targeted therapies that can help clear senescent cells from the body – in turn preventing them from contributing to age-related disease.

Here are four nutritive compounds that research shows can help eliminate senescent cells:

#1. Vitamin E
In the prevention category, research has shown that a class of vitamin E nutrients known as tocotrienols are powerfully senolytic. This means they prevent cells from turning senescent. Not only do tocotrienols help facilitate normal cell division while protecting healthy cells against turning senescent, but they also stimulate senescence in the only cells that actually need it: cancer cells!

#2. Quercetin
Similar effects have been shown with quercetin, a flavonol (antoxidant) found in many fruits and vegetables (including apples) that performs the same complementary actions in cells. Tocotrienols and quercetin may also work against existing senescent cells, helping to clear them from the body while simultaneously promoting the destruction and elimination of cancer cells.5

#3. Carnosine
The free radical scavenger carnosine (beta-alanine), an amino acid compound found in asparagus, watercress, white mushrooms, and other foods, may be similarly suited to target senescent cells. Research published in the journal Biochemistry back in 2000 found that carnosine can actually help to rejuvenate senescent cells while extending the lifespans of healthy cells. Carnosine further aids in the maintenance of cellular homeostasis, delaying the onset of age-related disease.6

#4. Polyphenols
Polyphenols, another type of micronutrient found in many plant-based foods, is another antioxidant compound that can play a powerful role in mitigating senescence. Polyphenols activate the production of a protein known as Nrf2, which some describe as the “guardian of lifespan.” The Nrf2 pathway is directly involved in the detoxification and elimination of reactive oxidants and electrophilic agents that promote aging, which include senescent cells.7

Other prominent examples of Nrf2-activating foods and nutritional compounds include:8

Epigallocatechin gallate (EGCG) – a catechin antioxidant found in green tea
Resveratrol – a polyphenolic antioxidant found in the skin and seeds of red grapes
Rosmarinic acid and carnosic acid – two antioxidant compounds found in rosemary
Curcumin – the primary active constituent found in turmeric
Isothiocyanates (i.e. sulforaphane) – a class of sulfur-containing compounds found in cruciferous vegetables like broccoli, Brussels sprouts, cauliflower, and cabbage
Diallyl sulfide and thiosulfonate allicin – two sulfur-containing compounds found in garlic
“All of these compounds are generally considered to be antioxidants,” concludes a 2010 study published in the journal Molecules.9 “They may be classified this way either because they directly scavenge free radicals or they indirectly increase endogenous cellular antioxidant defenses, for example, via activation of the nuclear factor erythroid-derived 2-related factor 2 (Nrf2) transcription factor pathway. Alternative mechanisms of action have also been suggested for the neuroprotective effects of these compounds such as modulation of signal transduction cascades or effects on gene expression.”

Cell Regeneration: A Matter of Life and Death
https://thetruthaboutcancer.com/cell-regeneration/