SciTech

How Things Work: The process of wound healing

Credit: Adelaide Cole/Art Editor Credit: Adelaide Cole/Art Editor

From childhood scrapes to the removal of wisdom teeth, the human body displays an amazing ability to heal itself. Once an injury occurs, a cascade of chemical reactions begins in a carefully regulated, multistep process until the damage is repaired.

Oftentimes we take this ability for granted and take risks that can lead to severe injuries. Without the healing process, our bodies would not be able to endure all the damage we expose them to throughout our lifetimes. Imagine the extreme care that would have to be taken if our bodies didn’t have this ability; even a simple paper cut could be deadly.

The skin, the largest organ in our bodies, acts as a protective barrier from the outside environment. Two layers of the skin, the epidermis and dermis, contain blood vessels that transport blood throughout the body. This protective barrier is broken after an injury, exposing blood vessels and causing bleeding.

As an instinctive attempt to stop bleeding, the body enters the first stage of the healing process, known as hemostasis. According to an article published in Alternative Medicine Review, chemicals are released by muscle tissue around the damage to constrict the damaged blood vessels, reducing the amount of blood flow to the area and limiting blood loss.

According to WebMD, tissue that makes up the skin underneath is made up of proteins called collagen. In the event of an injury, small disk-shaped structures in the blood called platelets interact with collagen and cause the blood to coagulate or stick together, forming a scab that temporarily seals the break in the blood vessel.

As the bleeding is controlled, the body slowly enters the inflammatory phase of healing that is often associated with pain. Here, the platelets release chemicals that attract special types of white blood cells to the wound. These cells flood the wound, acting as the body’s immune system, where they engulf and destroy debris and harmful bacteria. These cells act as the first line of defense against infection, dominating the area of the wound for the first two days.

Over the next few days, the white blood cells continue to digest bacteria and dead tissue cells. Once bleeding has subsided and the wound is free from infection, it enters the rebuilding stage. Also known as the proliferative stage, this stage is when cells create new collagen and increase the strength of the wound.

White blood cells known as fibroblasts eventually mature into smooth muscle cells. As they transform into what are known as myofibroblasts, they develop characteristics of muscles, such as the ability to contract. This establishes the final stage of wound healing, where the myofibroblasts pull the wound edges together. Over time, more collagen is deposited to protect the wound from reopening, creating scar tissue.

Although scar tissue and normal skin both contain collagen, scar tissue has a higher concentration of it, which makes it look different from the surrounding skin. Collagen in normal skin overlaps in many directions, giving a smooth appearance. In contrast, collagen in scar tissue is usually aligned in one direction, giving it a more textured look.

Our bodies contain all the cells necessary to rebuild damaged tissue. However, these cells require various vitamins and nutrients that must come from our diet. Vitamin C is used for collagen synthesis, and vitamin A is used to develop blood vessels. Other nutrients, such as zinc, are necessary for DNA synthesis for new developing cells.

Wounds are an inescapable part of human lives, and luckily, the human body can recover from the majority of minor cuts and scrapes with very little intervention. Larger wounds often need outside medical attention to more quickly stop bleeding or further prevent infection. Still, doctors rely heavily on the body’s ability to fix itself over time.