Integumentary system

The integumentary system is a bodily system that includes the skin and other skin-related structures. In animals and plants, the integumentary system serves to cover and protect the body's internal structures. The human integumentary system—which is composed of skin, glands, hair follicles, and nails—offers protection, helps to prevent water loss, contributes to the regulation of body temperature, and makes it possible for a person to interact with their external environment through the sense of touch. In other animal species, the integumentary system may consist not only of skin and glands but also feathers, scales, fur, shells, and exoskeletons. As with any other bodily system, the integumentary system can be affected by various diseases, including cancers, eczema, acne, vitiligo, psoriasis, and warts. These and other skin-related diseases can vary in severity, but all present some level of risk to one's broader health. Therefore, maintaining healthy skin is an important element of overall well-being.

Background

The primary component of the human integumentary system is the skin. The largest organ in the body, the skin has several important purposes. In addition to protecting internal organs and other structures from various types of damage, the skin produces different vitamins and hormones, helps to maintain a regulated body temperature and water balance, stores fat, and houses the nerves and nerve endings that allow for the sensation of touch, pressure, pain, and temperature. The skin performs these functions with the help of other integumentary structures such as nails, hair, sweat and oil glands, blood and lymph vessels, nerves, and muscles. The skin itself is composed of three separate layers, including the epidermis, dermis, and hypodermis.

The epidermis is the outermost layer of the skin. It is composed of epithelial tissue and contains both squamous cells and Langerhans cells. Squamous cells, or keratinocytes, produce a protein called keratin that makes up skin, hair, and nails. Dead keratinocytes found on the surface of the epidermis are continuously shed and replaced by the cells below. Langerhans cells help to alert the immune system when an infection occurs. At its innermost level, the epidermis also contains keratinocytes called basal cells that continually divide to produce new cells to replace the ones that die off and are shed. Two other special types of cells found in this layer are melanocytes and Merkel cells. Melanocytes produce the pigment melanin, which determines the color of one's skin. Merkel cells are touch receptor cells.

The dermis is located below the epidermis. It contains an array of important components. Some of these include blood vessels, lymph vessels, sweat glands, oil glands, hair follicles, sensory receptors, collagen, and elastin. Collagen is a structural protein that holds muscles and organs in place. Elastin is a rubbery protein that makes skin elastic and stretchable.

The hypodermis is the innermost layer of skin. It contains fat and loose connective tissues that help to insulate and cushion the body. The hypodermis also contains many of the same structures as the dermis, as well as mast cells. Mast cells are special white blood cells that heal wounds, help in the formation of blood vessels, and protect the body against disease-causing pathogens.

Overview

The skin is the body's largest organ. It weighs about 6 to 11 pounds (3 to 5 kilograms) and usually accounts for about 16 percent of a person's total body weight. It is composed of proteins, water, lipids, and various minerals and chemicals. The thickness of the skin's epidermal layer varies depending on location. The thickest skin is found on the palms of the hands and the soles of the feet. The thinnest skin is found on the eyelids.

Functionally, the skin's main purposes are to waterproof the body, protect it from infection, and cushion the internal organs. The skin's waterproofing properties arise from the presence of keratin, collagen, and elastin. One of the few substances that is normally secreted through the skin is sweat. Sweat is a waste product composed of water and other chemicals and is excreted through the skin via perspiration by sweat glands. The excretion of sweat helps to regulate body temperature, and the carefully controlled nature of perspiration prevents dehydration. The skin and hair also provide the body with natural defenses against disease, damage caused by ultraviolet radiation, and sunburn. Finally, the storage of fat, water, glucose, and vitamin D provides the body with needed insulation and cushioning.

There are many diseases that affect the skin. The most dangerous of these is cancer. The three main types of skin cancer include basal cell carcinoma, squamous cell carcinoma, and melanoma. Basal cell carcinoma is the most common form of skin cancer. It usually appears skin-colored or slightly pearl colored and typically does not spread to other parts of the body. Squamous cell carcinoma is the second most common. It appears as a rough-surfaced, skin-colored lesion and can sometimes be fatal. Melanoma is the most dangerous type of skin cancer. It presents as a dark skin spot that changes and bleeds and leads to death for about 35 percent of diagnosed patients.

Eczema is a condition that leads to red, flaky skin. Although it often appears on its own, it can also be caused by exposure to elements such as poison ivy. Eczema is usually treated with topical anti-inflammatory creams or ointments. Psoriasis is a similar inflammatory skin condition that leads to the appearance of red, itchy plaques on the knees and elbows. It is also usually treated with topical creams and light therapy.

Acne is a common integumentary disorder affecting the hair and oil glands. It typically appears in the form of pimples and red bumps that arise on the face, chest, and back. Acne is often the result of hormonal changes that occur during adolescence.

Vitiligo is a condition that affects skin color. It occurs when the melanocytes fail to produce melanin properly and results in patches of skin that are lighter in color than the rest of the skin. Vitiligo often occurs when melanocytes are attacked by the immune system, but it can also arise whenever these cells die or stop working. It is usually treated with light therapy.

Warts are rough bumps that appear on the skin as the result of a viral infection. Treatment usually involves irritating the wart so that the immune system can identify and kill the viral infection causing it.

Bibliography

"Integumentary System." Cleveland Clinic, 25 Apr. 2022, my.clevelandclinic.org/health/body/22827-integumentary-system. Accessed 3 Dec. 2024.

Kim, Joyce Y., and Harry Dao. "Physiology, Integument." StatPearls, 1 May 2023, www.ncbi.nlm.nih.gov/books/NBK554386/. Accessed 3 Dec. 2024.

Moriello, Karen A. "Overview of Integumentary System." Merck Veterinary Manual, Jan. 2020, www.merckvetmanual.com/integumentary-system/integumentary-system-introduction/overview-of-integumentary-system. Accessed 3 Dec. 2024.

Smith, Courtney. "Anatomy and Physiology: Five Things about the Integumentary System." Visible Body, 20 Oct. 2015, www.visiblebody.com/blog/anatomy-and-physiology-five-things-about-the-integumentary-system. Accessed 3 Dec. 2024.

Gora, Anna, and Kim Ann Zimmerman. "Skin: Facts, Diseases & Conditions." LiveScience, 17 Apr. 2023, www.livescience.com/27115-skin-facts-diseases-conditions.html. Accessed 3 Dec. 2024.