You Positively Glow!
Your skin uses a number of different structures to perform its functions—and it does more than just keep germs from getting in.
Sweat and Sebaceous Glands
The skin is an intact (contiguous) sheet of cells that protects the human body. Accessory structures enable the skin to cool the body and condition the skin itself. These important glands are the sweat glands and the sebaceous glands.
Sweat Glands
In ancient times, Egyptians hung wet linen cloth in doorways and windows to cool the inside of their living areas. As the water evaporated, it cut down on the heat in the air and effectively cooled the rooms. The human body uses this same approach to cool down. This is called sweating. When the surface of the skin is wetted, evaporation occurs, and as it does, heat dissipates and your body temperature is lowered.
Why some sweat smells
Eccrine sweat glands can be found over the majority of the body and produce the fluid that cools the human body known as sweat. Apocrine sweat glands can be found in greater density in the armpits and produce a different type of sweat that when metabolized by bacteria produces a distinctive and often unpleasant odor.
The secretory portion of the sweat gland resides in the deeper parts of the dermis and produces the salty protein-and-lipid-rich fluid known as sweat. This is passed through long, coiled ducts upward and through the epidermis to be released onto the surface of the skin.
Sebaceous Glands
Sebaceous glands can be found in the dermal layer of the skin and are attached to the sides of hair follicles. Sebum, a waxy secretion produced by these glands, is injected into the hair follicle, coats the shaft of the hair, and is eliminated onto the surface of the skin. This material aids in the waterproofing and lubricating of the skin and hair in mammals.
Wound Healing
An intact layer of skin is critical in preventing infectious agents from gaining access to deeper regions of the body including the blood stream. Therefore, when an injury to the skin occurs, rapid and complete repair or closure of the wounded area must be accomplished. All layers of skin are involved in the repair process.
Inflammatory Phase
The body’s initial response to a wound is to minimize blood loss. Damaged blood vessels reflexively constrict to slow the flow of blood to the damaged area. At the same time, platelets, blood cells that perform a clotting function, activate and begin the process of forming a platelet plug to prevent the further loss of blood cells and to decrease the loss of blood plasma at the injury site. This plug forms the initial foundation of the full blood clot.
At the same time, the body floods the injured site with body fluid and immune cells to flush the area of pathogens and bring in white blood cells to destroy any pathogens that remain. This inflammatory process is a nonspecific means by which the body fights off any potential infection.
Proliferative Phase
As the wound site becomes filled with the blood clot and infiltrating white blood cells, connective tissue cells, or fibroblasts, migrate into the area and begin to deposit a temporary scaffolding of connective tissue molecules to fill in the open gap in the skin. This material is the start of granulation tissue; it helps close the wound and provides a foundation for the normal tissue constituents to regrow and re-form the original state of the skin.
Since the surface of your skin is epithelial and not connective tissue, those epithelial cells on the edges of the wound start to multiply and spread. They overgrow the granulation tissue. To provide nutrients to the newly growing tissue, blood vessels grow into the granulation tissue and form new circulation.
Tissue reconstruction continues as the wound is repaired and as the body attempts to close it. The blood clot starts contracting and pulls the edges of the wound closer together, resulting in a smaller area to form new tissue.
How do scars occur?
Scars occur when there is an overproduction of connective tissue proteins such as collagen, which prevents the formation of normal epithelial tissue over the wound site. If the wound is too wide or the granulation tissue grows too extensively, then re-epithelialization cannot occur. This results in a scar.
Maturation Phase
In the final weeks of wound repair, the last portions of granulation tissue will be removed, all clotting material will be eliminated from the site, and the resident constituents of the skin will be properly formed in the exact proportions and in the correct area. Following this period, most repairs of small wounds will result in skin that shows little to no sign of any injury or defect at all.
Temperature Regulation
Most people know that the skin protects your body from disease and from dehydration. However, few are aware of the role the skin plays in temperature regulation of the body.
Sweat
As discussed earlier, when you’re hot, your body will sweat. As the liquid on the surface of your skin evaporates, heat is liberated from the skin and dispersed into the air, cooling the skin. In this way, the skin and the associated blood vessels that supply the skin can be thought of as a radiator or a heat exchanger between the human body and the environment.
Conserving Heat
The skin and its vascular supply also play a critical role in conserving body heat when the core body temperature begins to decrease, such as on very cold days. When exposed to the cold, the skin of the hands and face will initially flush and turn red, which indicates the dilation of the blood vessels near the skin surface in an attempt to bring more of the body’s core temperature to the skin and keep the tissue warm.
This attempt to warm the body will only continue up to a point. When the body’s core temperature falls enough, the blood supply to the skin is restricted and the blood is redirected to deeper (core) areas of the body. This is the body’s way of sacrificing less important areas to keep the core of the body’s temperature from falling too low.