Integumentary System Functions

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This article looks at the human integumentary system and gives a brief overview of the integumentary system functions.

The integumentary system is a fancy word that encompasses the skin and all of the tissues that form out of the skin, such as nails, hair, and some glands.

The skin is the largest organ in humans. Herbalists rely on the physiology of the skin to better understand an individual. Is the skin hot or cold? Clammy or dry? What color tone is the skin presenting with? Are there noticeable blemishes on the skin? etc.

Many problems that people associate with the skin have roots in other systems. For example, rashes may indicate a problem with the liver, the digestive system, or the immune system.

Skin

The skin has five major functions.

• Protection: First and foremost the skin protects the underlying structures by providing a physical barrier against the external environment. This can include anything from pathogens to abrasions.
  
  
• Temperature homeostasis: The skin helps to regulate temperature by perspiring when the body becomes too hot. When the body has become too cold, blood vessels near the surface of the skin constrict to prevent heat from leaving the body.
  
  
• Sensation: Nerve fibers that run throughout the layers of the skin help us to sense touch, temperature, pressure, and pain.
  
  
• Elimination: The skin is one of our eliminatory organs. Perspiration removes natural metabolic wastes from the body. (Traditionally, sweating has been an important part of a health regimen.)
  
  
• Vitamin D production is another important part of the skin’s functions.
  
  

Skin Layers

There are three skin layers.

Epidermis

The most superficial layer is the epidermis. This is the thin outer layer that protects the body from pathogens, excessive water loss, and UV rays. This layer of skin is constantly reproducing through stem cells. This cell division starts at the innermost layer of the epidermis. As more cells are reproduced, old cells are migrating closer to the surface. The process of new cells being created to old cells being sloughed off at the surface takes about four weeks.

Dendritic cells are a type of white blood cell that are located within the epidermis. These cells are an important part of the immune system and can detect and kill pathogens.

Also located within the epidermis are melanocytes. Melanocytes are specialized cells that produce melanin, which, along with carotene and hemoglobin, play an important role in skin color. Melanin is the pigment that determines skin color. Concentrated areas of melanin are what make freckles.

In people with light skin, exposure to UV rays increases the production of melanin and creates a darker skin color. The darker the color of skin the more protection there is against UV rays.

Dermis

The next layer of skin is the dermis. It is made up of fibrous connective tissue. These tissues allow strength, the ability to stretch, and elasticity to the skin. Also located in the dermis layer of skin are touch receptors. Unlike the epidermis, the dermis contains both nerves and blood vessels.

The temperature regulation aspects of the skin are also located in the dermis.

The human body maintains a steady body temperature despite diverse environmental temperatures. Although 98.6 F. is commonly quoted as a “normal” body temperature there is a small variation of this temperature in all people. Temperatures that vary more than 1.5 degrees F. signify a problem.

The hypothalamus in the brain is responsible for maintaining a steady temperature in the body. When things get too hot, blood vessels in the dermis dilate and blood flow is increased. This helps to cool the body both by heat loss through the skin but also by creating perspiration that then evaporates and cools the body.

If the body becomes too cool then blood vessels in the dermis are constricted, helping to prevent heat loss through the skin.

Hypodermis

The hypodermis is the last layer of skin. It is made up of superficial fascia and adipose or fat tissues. This layer of skin attaches the dermis to the tissues and organs under the skin. It also plays an important role as insulation, both at keeping heat in the body and preventing heat from entering the body.

Hair

Hair is comprised of a shaft and a root. The hair root grows inside of a hair follicle, which is a tubular inward growth in the epidermis. The hair shaft is the section that grows above the skin surface.

Each hair follicle has a muscle that constricts with coldness or when a person is frightened. The result of this constriction is goosebumps.

Humans have hair on practically all parts of the body. It provides various forms of protection. For example, eyebrows and eyelashes protect the eyes from sunlight, particles, and even perspiration. Hair within the nasal cavity prevents dust and foreign objects like insects from entering.

Nails

Fingernails and toenails are keratinized cells formed from the epidermis. Nails consist of two parts, the root from which the nail grows and the body, which is visible externally. Nails also serve protective purposes. The lunula is a white moon-shaped structure that is located near the root of the nail.

Summary

The human integumentary system is made up of the skin, nails, hair and some glands. The integumentary system functions are varied but overall it provides a barrier that protects our body from infection. Signs that the integumentary system isn’t healthy may be rashes, brittle nails and unhealthy hair. Oftentimes these signs point to an underlying cause of disease in the body.