Healing is such an amazing process, even more astounding when you research all the stages that your body goes through in the process. There are literally hundreds, if not thousands, of processes involved for a healing to take place. The ability to heal could not have developed in a Darwinian process that is slow and gradual. Half stopping the bleeding is not enough.
Let me share just a summary of a few of those processes with you, but first, here is a quote that I found that shows scientists really can't explain the whole process very well at all.
"Despite the advances in understanding the science of wound healing, many more steps have yet to be discovered and elucidated.
"Although seemingly basic in concept, advances in molecular science have allowed modern medicine to gain a true appreciation of the complex interplay between the cells involved in the phases of wound healing."[1]
Note that it is still too complicated for them to understand. How can they believe it happened by chance? They just assume no God and make up theories from there.
To continue, scientists vary as to whether there are 3 or 4 phases to the healing process, but regardless of how many, they agree that there are distinct things that happen.
"When your skin gets cut, your body springs into action to heal the wound. First, the body works to limit blood loss by reducing the amount of blood flowing to the wounded area. Proteins in blood, such as fibrin, work with the blood platelets already in place and plasma to form a protective covering called a scab. While your skin regenerates underneath the protective layer, the scab protects the wound from outside infection."[2]
Notice that your blood vessels leading to the wound constrict at first to limit the blood loss. Wounded cells release thromboxane A2 and prostaglandin 2-alpha which cause the vessel constriction. Once blood loss stops, then the blood vessels expand to allow more white blood cells to accumulate and get rid of infection, bacteria and debris. They do the opposite of what they did before. How is that possible?
"Platelets (triggered by enzymes leaked from the torn blood vessel) rush to the scene. These sticky blood cells clump to each other and then adhere to the sides of the torn blood vessel, making a plug. Clotting proteins in the blood join forces to form a fibrin net that holds the platelet plug in place over the tear, and in just a few seconds or minutes (depending on how bad the scrape is), BLEEDING STOPS, thanks to coagulation! The fibrin plug becomes a scab that will eventually fall off or be reabsorbed into the body once healing is complete."[3]
The scab makes a dry, temporary crust which protects the damaged area during healing.
The blood contains lots of platelets for just this purpose. Platelets only exist in animals. They are produced in a totally different location in your body, namely the bone marrow. A healthy adult produces about 1,000,000,000,000 platelets a day and they only circulate for about 8 to 9 days before being removed by the spleen and liver. Platelets are so tiny they are only 1/5th the size of red blood cells. Note carefully this quote: "Complicating any verbal description is the fact that at least 193 proteins and 301 interactions are involved in platelet dynamics." i.e. the making of platelets.[4]
If this process evolved in a slow and gradual way, the body would bleed to death and die before it could reproduce. Think of all the times you get injured and bleed during your lifetime.
Of course evolutionists would probably say that the healing ability was developed long before humans came along. But the problem for simpler organisms is even more complicated. They are much more likely to die from a simple wound than we are. The odds are less they could ever reproduce. The healing process is extremely complicated. Therefore, it could never evolve in one generation according to the Theory of Evolution. And what about platelets only existing in animals? They must have been created by God or the first animals would have bled to death before they could "evolve".
The next phase of healing is Inflamation. The blood vessels that previously constricted to stop blood loss now dilate to bring more blood to the area. The area swells up and the extra blood brings the white blood cells which engulf and kill bacteria and remove debris. Fibroblast cells also gather at the site and start producing collagen which gradually fills up the wound under the scab and creates new capillaries.
Skin cells around the edges of the wound thicken up and gradually stretch under the scab into the center of the wound, meeting skin from the other side. This takes about 3 weeks. This tissue forms a scar which gradually becomes stronger as more collagen is added, taking up to 3 years to complete the healing.
Here is a description of the next phase, called Proliferation. "The proliferation phase is characterized by angiogenesis, collagen deposition, granulation tissue formation, epithelialization, and wound contraction. In angiogenesis, vascular endothelial cells form new blood vessels. In fibroplasia and granulation tissue formation, fibroblasts grow and form a new, provisional extracellular matrix (ECM) by excreting collagen and fibronectin. Concurrently, re-epithelialization of the epidermis occurs, in which epithelial cells proliferate and 'crawl' atop the wound bed, providing cover for the new tissue."[5]
That's a lot of different processes going on involving all kinds of different specialized cells and chemicals. Healing doesn't work if any of these processes are not functioning. So how could evolution by slow and gradual changes possibly create such an intricate system?
We're not done yet. Wound contraction takes place by cells called myofibroblasts contracting like muscles and shrinking the wound. Then unneeded cells die off, somehow knowing they are not needed.
The last phase is Maturation and Remodeling where cells realign themselves like the original skin and unneeded cells die off. "Increased collagen production and breakdown continue for 6 months to 1 year after injury. The initial type III collagen is replaced by type I collagen until a type I:type II ratio of 4:1 is reached, which is equal to normal skin. Also, fibroblasts differentiate into myofibroblasts, causing tissue contraction during this phase of wound healing. Collagen reorganizes along lines of tension and crosslinks, giving added strength." [6]
How do the cells know what the original skin looked like and then be able to replace it?
The above article and description are extremely simplified. Read up on it a little if you are interested. If not, take my word for it, healing ability is no accident.
There is a God.
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[1] Wound Healing and Growth Factors, by Allen Gabriel, MD; http://emedicine.medscape.com/article/1298196-overview
[2] How Your Skin Works, How Skin Heals, by Rachel Oswald, http://health.howstuffworks.com/skin-care/information/anatomy/skin4.htm
[3] How do wounds, cuts, scrapes, lacerations heal? Go Ask Alice, http://goaskalice.columbia.edu/how-do-wounds-cuts-scrapes-lacerations-heal
[4] Wikipedia article on Platelets. http://en.wikipedia.org/wiki/Platelet
[5] Wikipedia article on Wound Healing. http://en.wikipedia.org/wiki/Wound_healing
[6] Wound Healing and Growth Factors, Phases of Wound Healing by Allen Gabriel, MD; http://emedicine.medscape.com/article/1298196-overview#aw2aab6b4