Our Incredible Regenerating Body

Allah, the Exalted says in the Qur'an:

وَفِي أَنفُسِكُمْ أَفَلَا تُبْصِرُونَ

And within your own bodies, will you not look (and reflect) (51:21)

The human body is a remarkable machine - every minute of every day our cells are in a constant state of change, building a new body, repairing it and regenerating it. Each tissue has its own renewal time, depending on how much that particular organ or area is used by us each day. By breaking the body down into different areas, this article explains the amazing phenomenon of our continually regenerating body.
The skeleton
The human skeleton is made up of 206 bones. Study has shown that each bone's shape is perfectly adapted to its function within the body.
A skeleton will completely renew itself about every ten years. This obviously doesn't happen all in one go, but over our lifetime, this process ensures optimum protection of our internal organs.
The heart
The heart is an extraordinarily reliable muscular pump, pumping around 6 liters of blood around the body every minute.
Researchers have confirmed that some heart cells renew themselves over the course of a person's lifetime, although this process can take decades. This means that by the age of 70, up to 40% of our heart may be renewed. This provides great potential for anyone who has suffered damage to their heart.
The liver
The liver is the body's largest internal organ. It consists of around 50,000 tiny units called hepatic lobules, which filter blood from the heart and intestines.
These liver cells, or hepatic cells, renew themselves regularly. These cells are exposed to toxins on a daily basis, which increases their potential for damage. The approximate lifespan for a liver is 150 days, after which the cells being to renew themselves and the liver regenerates. This ensures the liver continues to work optimally. However, excess toxic intake from harmful substances can put extra strain on this process and cause damage to occur at a greater speed than regeneration, resulting in permanent damage to the cells.
The skin
The skin is the largest external organ of the body and is made up of three crucial layers: the epidermis (the outer layer), the dermis (the second layer) and the sub-dermis (the third layer). The surface of the skin consists of flat, interlocking dead cells, which wear away and are replaced by cells moving up from below, like a conveyor belt. The cells are produced at the base of the skin's outer layer, the epidermis.
We shed around 60,000 particles of skin a day, and it is completely renewed every 28 days.
The hair
Hair follicles, from which hairs grow, are found in the second layer of skin, the dermis. Only the base of the hair, where it grows, is alive, and the shaft that shows above the surface is dead.
The speed at which our hair generates is dependent on where it is on the body. Head hair grows at a rate of 1 mm every three or four days and renews every six years, so after six years the hair on our head will be a completely different batch to the one six years prior. Hair elsewhere may be renewed quicker if exposed to daily damage or removal.
The red blood cells
Red blood cells are some of the smallest cells in the body - only one drop of blood contains millions of red blood cells. 45% of our blood is made up of red blood cells, and they are the main way that oxygen is delivered to the internal organs. They are a fundamental part of our ability to thrive, so red blood cells are renewed very three to four months.
The intestines
The 'villi', which look like tiny hairs, are the parts of the small intestine that are vital for the absorption of nutrients from food. There are around 4,000 villi in an area the size of a fingernail, so they provide a huge surface area to maximize absorption of nutrients. These structures are used every time we eat or drink for the stomach acid needed to break down food, so are essential for optimum health. As a result, they need to be renewed regularly. New villi take the place of old cells every two to three days.
The mouth and taste buds
The cells of the mouth's lining, including the inside of the cheeks and surface of the tongue, multiply to renew themselves every few hours. This rapid replacement is needed to cope with the continual wear and tear of biting, chewing and swallowing.
The tongue's surface is roughened by papillae or 'pimples' of several shapes and sizes. Around 10,000 microscopic taste buds are scattered around these pimples and also on the roof of the mouth and upper throat. Used on a daily basis, our taste buds can get very worn out. In order to maintain our ability to taste and detect different flavors, our taste buds are renewed every ten days to two weeks.
The Crucial Role of antioxidants
Unfortunately, there are also some areas that are not regenerated. Although some parts of the brain can be renewed by stem cells, the majority of it cannot and it is the reason why most brain damage is permanent. The eyes (apart from the cornea) will also not be able to recover from damage, as well as teeth that become decayed.
Antioxidants play a fundamental role in both repairing damage to old cells and also to renewing them. A dietanti packed with oxidants is vital to support the regeneration process or to protect organs like the eyes or brain from damage. Found naturally in fruits, vegetables, nuts, pulses or through naturally sourced food supplements, these beneficial substances are crucial for a healthier and younger-looking body. 
Source :  http://www.healthymuslim.com/