The components of the integumentary system consist of the skin, hair, and nails. The integumentary system is the first line of defense against disease and pathogens entering the body. And, the integumentary system regulates body temperature, provides sensory input and synthesizes vitamin D.

This article will look at the components and the accessory structures of the integumentary system, skin healing, skin integrity, and the staging of pressures ulcers. This article contains 7 Facts about the Integumentary System Every Nursing Student Should Know.

Fact #1: The Skin has Three Layers

The skin is the largest organ of the body. It is the protective covering of the body. Also, the skin has more exposure to the environment than any other organ. The skin has three layers. These layers are the epidermis, dermis and hypodermis also called the subcutaneous fascia.

Epidermis

The epidermis is the top layer of the skin. This is the skin we see. Stratified squamous epithelium cells form this layer.  The epidermis layer does not have blood vessels and does not contain nerve endings.

The stratum corneum is the outer layer of the epidermis. This layer consists of dead skin cells. The stratum corneum sloughs off with daily activities. Therefore, this continuous turnover of cells allows for the skin to repair itself when injured.

The epidermis also contains cells called melanocytes. The melanocytes are cells that produce melanin. Melanin affects the color of the skin. Every person has the same number of melanocytes.

The color of a person skin is depended upon how much melanin is produced and how the melanin is distributed. The sun causes a person to produce more melanin. This is why you get darker when exposed to the sun.

Dermis

The dermis is the layer of skin directly below the epidermis. The dermis is much thicker than the epidermis. It consists of connective tissue. This layer contains blood vessels (capillaries), nerve endings, sebaceous glands, hair follicles, elastic fibers, collagenous fibers, involuntary muscles, lymph vessels, and sweat glands.

1. Blood vessels (capillaries) – The blood vessels in this layer cause a person to blush.
2. Nerve endings – The nerve endings in this layer of skin allow for the sensing of the environment.
3. Sebaceous glands – These are oil glands. The sebaceous glands secrete oil called sebum. Sebum keeps the skin from drying out.
4. Elastic fibers and Collagenous fibers – These fibers allow for flexibility and movement of the skin when a person moves. Also, these fibers return the skin to normal after it has been stretched.
5. Sudoriferous glands – These are the sweat glands. There are two types: apocrine and eccrine. The apocrine glands secrete at groin, armpits and anal region. The eccrine glands secrete at the palms of the hand, feet, forehead and upper lip. The eccrine glands are also responsible for body temperature regulation.
6. Additionally, there are involuntary muscles, lymph vessels, and hair follicles located in this layer.

A person’s fingerprints originate from the dermis.

Hypodermis (Subcutaneous fascia)

The hypodermis is the bottom layer of the skin. This layer is composed of connective and fatty tissue.

It produces the fat cells that provide the padding for protection, insulation and temperature regulation. The hypodermis attaches to the muscles of the body.

Fact #2: The Skin has Several Vital Functions

Protection

The skin has strength from the collagen located in the dermis of the skin. This layer makes the skin resistant to objects that may penetrate it.

Also, the skin protects the body against invasion of bacteria. There are microorganisms located on the skin normally that compete with harmful bacteria that may invade the body.

The skin located on the palm of the hands and the sole of the feet protect them against the constant trauma.

The top layer of the epidermis, the stratum corneum is the most effective portion of the skin for protection. The stratum corneum contains lipids which make this layer a great waterproof barrier.

Regulation of temperature

The body had different methods of regulating temperature. The body constantly produces heat due to metabolism. The heat dissipates through the skin. Vasoconstriction and vasodilation of the blood vessel underneath regulate body temperature. When the body is too hot the vessels dilate.

Vasodilation causes the blood vessels to get larger. This gets the hot blood to the surface of the skin and to the cooler environment. Conversely, when the body is too cold the vessels constrict.

Vasoconstriction causes the blood vessels to get smaller. This causes the blood to move away for the skin surface to the core of the body which is warmer.

Also, the processes or radiation, conduction and convection help regulate body temperature.

Radiation involves the transfer of heat to another object that is cooler.

Conduction is the transfer of heat to another object that is cooler by touch.

Convection is the transfer of heat to the air surrounding the body.

The body can also regulate its temperature through sweating. A person does not sweat until the body’s temperature exceeds 98.6F. Sweating may also be a reflex that is not related to temperature.

Sensitivity

There is a dense network of nerve endings in the dermis of the skin that makes it sensitive to pressure, pain, temperature, and touch.

This layer also allows the body to monitor the environment. There are more nerve endings in some parts of the body than others.

For example, the fingertips are more innervated with nerve endings than the rest of the hand.

Manufacture of Vitamin D

The skin produces vitamin D (Cholecalciferol) in response to exposure to sunlight. The vitamin D helps regulate calcium metabolism. Also, vitamin D is essential for the prevention of osteoporosis.

Fact #3: The Nails are an Extension of the Skin.

The nails are an extension of the epidermis. The nails originate from epithelial cells from a nail root.

The cells grow over the epidermis layer of the skin. The cells are a keratin substance. This substance is similar to the top layer to the epidermis. 

The parts of the nail include the free edge, nail bed, nail body, lunula, hyponychium, cuticle, and nail matrix.

1. The free edge is the part of the nail that extends beyond the fingertip.
2. The nail bed is the area underneath the entire nail.
3. The nail body is the main part of the nail which is exposed.
4. The lunula is the opaque moon-shaped area of the nail.
5. The hyponychium is the area where the nail body is attached just below the free edge.
6. The cuticle is a fold of tissue that covers the nail root.
7. The nail matrix is the portion of the nail that attaches the nail body to the nail bed.

Fact #4: The Hair Originates from the Skin Layers.

Millions of hairs cover the human body. The only portion of the body not covered with hairs is the lips, nipples, parts of the genitalia, the palm of the hands and the sole of the feet.

The hair of the body can detect things on the skin. The hair in the nose acts as a filter and the eyelashes protect the eyes. The same keratin that forms the nails and the top layer of the epidermis forms the hair.

The shaft, the root, the cortex, the medulla, the follicle, and the cuticle form the hair.

1. The shaft is the portion of the hair that you see.
2. The cuticle covers the shaft of the hair.
3. The cortex contains melanin and gives hair its color.
4. A person with coarse hair has an extra layer of cells beneath the cortex called the medulla.
5. The root of the hair extends down into the dermis to the follicle.
6. Epithelial cells form the follicle. Hair cells divide and grow from the follicle.

Also, sebaceous glands or oil glands are associated with hair follicles.

The sebaceous glands secrete sebum which coats the skin and the hair. The sebum works its way up the hair to the surface of the skin. The sebum coats the skin and the hair shaft making it waterproof.

Fact #5: Skin can Heal Itself

Since the skin is the largest organ and the most exposed, it can become damaged. Therefore the body has developed a way for the skin to repair itself.

Primary Intention

There are two types of wounds. Firstly, there is the type of wound without tissue loss. An example would be a surgical incision.

This type of wound will heal by primary intention. The wound closes when the edges are pulled together.

There is a low risk of infection with this type of wound. Also, this type of wound heals quicker and there is less scar tissue formation.

Secondary Intention

Secondly, there is the type of wound that does have tissue loss. An example of this type of wound would be a pressure ulcer.

This type of wound heals by secondary intention. This type of wound is left open and regeneration occurs. Scar tissue will develop when these wounds are large.

Scar tissue is collagen fibers that do not contain any accessory organs that the layers of the skin normally contain.

Conversely, this type of wound takes longer to heal and has a greater chance of infection. There can be a permanent loss of tissue for severe wounds.

Regeneration

Healing by regeneration occurs when the skin is damaged affecting the blood vessels. 

• First, the wound begins to fill with blood.
• Next, the blood forms a clot which then hardens to a scab.
• The scab is protection from the environment and anything that may enter the wound such as pathogens.

An injury to the skin causes the inflammatory process to begin.

• First, white blood cells migrated to the wound to destroy any pathogens that may be present in the wound.
• Next, cells that develop into connective tissue begin to pull the edges of the wound together. These cells are the fibroblast.
• Finally, the epidermis begins to produce new cells at an accelerated rate to repair the wound.

Fact #6: Impaired Skin Integrity is the Biggest Problem with the Skin.

Impaired skin integrity is a major problem seen by nurses in most settings. Impaired skin integrity is usually related to prolonged pressure.

This results in pressure ulcers. Other names for pressure ulcers are pressure sores, decubitus ulcers, and bedsores.

Pressure ulcers are injuries to the skin and underlying tissue caused by pressure, friction or shearing force.

The ulcers interrupt the integrity of the skin and decrease its effectiveness of the skin as protection.

The formation of pressure ulcers is due to the intensity of the pressure, the duration and the tolerance of the tissue.

Intensity

The intensity placed on a body part for a prolonged period of time can cause a pressure ulcer.

Occlusion of the vessel occurs with long periods of pressure. Capillaries close during this period. 

Tissue ischemia results with occlusion of the vessel. Tissue ischemia can lead to tissue death.

With the relief of the pressure, the area will become red due to the vasodilation of the blood vessels. The redness is called hyperemia.

Hyperemia is normal when the episode of ischemia is transient. To determine hyperemia, test the skin for blanching.

Blanching is when the skin turns a light color with the application of pressure by the finger. If the reddened area blanches, the area is attempting to overcome the episode. If the tissue does not blanch there may be a deeper tissue problem.

Duration

A pressure ulcer can develop with the exposure of an area to pressure for a long period of time or a short period of time.

Tissue exposed to high pressure for a short period of time will form a pressure ulcer.

Likewise, with the exposure of tissue to low pressure for a long period of time, a pressure ulcer can form.

So, always assess tissue with exposure to pressure for a short or a long period of time.

Tolerance

The integrity of the skin and supporting structures will determine the ability of the tissue to endure pressure.

Patients who are older, have poor nutrition or have an underlying pathology do not tolerate pressure to tissue for long periods of time.

With these factors, the persons supporting structures and blood vessels may make them vulnerable to acquire pressure ulcers.

Also, factors such as shearing, friction, and moisture may affect the ability of a patient to tolerate pressure to the tissue.

Fact #7: There is a System for Classifying Pressure Ulcers.

Pressure ulcers are classified by staging. Most hospitals no longer require nurses to stage pressure ulcers.

A nurse specializing in wound care and ostomies will do the staging.

However, a student nurse should be aware of the different stages that are charted on a patient.

The National Pressure Ulcer Advisory Panel  (NPAUP) has a four-stage classification system. Their method of staging is listed below. You can also visit their website for the picture of these stages.

Stage 1 Pressure Injury: Non-blanchable erythema of intact skin

Intact skin with a localized area of non-blanchable erythema, which may appear differently in darkly pigmented skin. Presence of blanchable erythema or changes in sensation, temperature, or firmness may precede visual changes. Color changes do not include purple or maroon discoloration; these may indicate deep tissue pressure injury.

Stage 2 Pressure Injury: Partial-thickness skin loss with exposed dermis

Partial-thickness loss of skin with exposed dermis. The wound bed is viable, pink or red, moist, and may also present as an intact or ruptured serum-filled blister. Adipose (fat) is not visible and deeper tissues are not visible. Granulation tissue, slough, and eschar are not present. These injuries commonly result from adverse microclimate and shear in the skin over the pelvis and shear in the heel. This stage should not be used to describe moisture associated skin damage (MASD) including incontinence associated dermatitis (IAD), intertriginous dermatitis (ITD), medical adhesive-related skin injury (MARSI), or traumatic wounds (skin tears, burns, abrasions).

Stage 3 Pressure Injury: Full-thickness skin loss

Full-thickness loss of skin, in which adipose (fat) is visible in the ulcer and granulation tissue and epibole (rolled wound edges) are often present. Slough and/or eschar may be visible. The depth of tissue damage varies by anatomical location; areas of significant adiposity can develop deep wounds. Undermining and tunneling may occur. Fascia, muscle, tendon, ligament, cartilage and/or bone are not exposed. If slough or eschar obscures the extent of tissue loss this is an Unstageable Pressure Injury.

Stage 4 Pressure Injury: Full-thickness skin and tissue loss

Full-thickness skin and tissue loss with exposed or directly palpable fascia, muscle, tendon, ligament, cartilage or bone in the ulcer. Slough and/or eschar may be visible. Epibole (rolled edges), undermining and/or tunneling often occur. Depth varies by anatomical location. If slough or eschar obscures the extent of tissue loss this is an Unstageable Pressure Injury.

http://www.npuap.org/resources/educational-and-clinical-resources/npuap-pressure-injury-stages/

Conclusion

The skin is one of the largest organs and plays many important roles in maintaining the integrity of the body. This article 7 Facts About the Integumentary System Every Nursing Student Should Know will give you a better understanding of the skin, the accessory structures and the roles it plays in maintaining many of the functions of our body.

Reference

Ignatavicus D., Workman L., Rebar C., Medical-Surgical Nursing: Concepts for Interpersonal Collaborative Care. 9th ed. St Louis, MO: Elsevier Inc. 2018.

Lewis S., Bucher l., Medical-Surgical Nursing: Assessment and Management of Clinical Problems. 10th ed, St Louis, MO: Elsevier Inc. 2017.

Mosby’s Medical Dictionary (2017). 10th ed. St Louis, MO. Elsevier Inc.

Potter P., Perry A., Fundamentals of Nursing. 7th ed. St Louis, MO. Elsevier Inc. 2009.

The National Pressure Ulcer Advisory Panel  (NPAUP). www.npaup.org.

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