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Integumentary System: What to Know

Medically Reviewed by Dany Paul Baby, MD on September 01, 2022

The integumentary system is the physical system that forms the barrier between the external environment and the internal systems of the body. In humans, this system consists of skin, hair, nails, and related glands. 

Altogether, the integumentary system forms the largest organ in the body. The main function of this system is to protect bones, organs, and other internal structures from harm. In addition, the integumentary system performs important immune functions, cell fluid maintenance, synthesis of Vitamin D, body temperature regulation, and detection of stimuli.

How Does the Integumentary System Work?

The integumentary system has five components: skin, hypodermis, hair, nails, and exocrine glands. The different components work together to maintain health and well-being for the rest of the body.

They offer:

Protection. The epidermis and dermis form a physical barrier that protects all the internal body parts. The skin protects against negative effects of your environment such as heat, cold, and sun exposure, and it prevents many foreign substances, such as bacteria, viruses, and environmental contaminants, from getting inside the body. The hypodermis layers beneath the skin provide additional cushioning for internal organs. Hair and nails offer additional protection for sensitive areas of the body, such as fingers, toes, and face. 

Nutrition. Your body makes its own vitamin D through a process called synthesis. This process is triggered when the skin is exposed to sunlight. Vitamin D is crucial for bone health.  

Immunity. The skin blocks the direct entry of pathogens like viruses and bacteria, preventing illness and infection. In addition, the skin produces antimicrobial peptides (AMPs) and lipids, which can destroy bacteria that come in contact with the skin. Immune system cells located within the skin can also send signals to the greater immune system and trigger an immune response. 

Wound healing. Many wounds damage the skin itself. An injury to the skin activates clotting mechanisms to stop bleeding and form a protective layer over the wound. After that, immune cells will rush to the site to prevent infection. The final healing phases involve the formation of new skin cells and the formation of connections between the cells.

Temperature regulation. The skin plays an important role in keeping the body temperature within a safe range. When your body heats up, blood vessels along the entire surface area of the skin dilate to allow heat to dissipate. Additionally, sweat glands secrete fluid that leads to cooling via evaporation. When the body is colder than normal, the skin triggers hair follicles to rise up, causing a reaction commonly called goosebumps. The raised hairs trap warm air close to the skin and prevent heat from leaving the body. 

Sensory input. The skin is threaded with nerve cells that detect pain, heat and cold, pressure, and vibration. These sensations associated with touch help you understand your environment and respond appropriately to stimuli. 

Where Is the Integumentary System Located?

The integumentary system covers most of the body. It makes up the outer layer of the body, leaving only organs like the eyeballs uncovered. 

Skin:The outermost layers of the skin, which cover most of the human body, include the epidermis and dermis. The topmost layer is the epidermis, which serves as the body’s first line of defense against illness and injury. The dermis is the layer beneath the epidermis. This layer is the connective tissue that supports the epidermis. It contains blood and lymph vessels, nerves, sweat glands, and hair follicles. 

Hypodermis: The hypodermis is the third layer of skin. It is the layer of tissue that lies directly beneath the dermis. It’s sometimes called subcutaneous tissue. It’s a combination of connective tissue and adipose tissue that provide additional protection for the inner organs. 

Hair: Hair grows on nearly all areas of the epidermis. Hair differs in length and thickness depending on where it appears on the body, though. It offers protection for the skin, increases sensory function, and helps regulate body temperature. 

Nails: Nails are layers of keratin that form hard plates. They grow over the tips of the fingers and toes. Nails protect the digits and aid in dexterity. 

Glands: Four types of glands make up integumentary system parts: sudoriferous, sebaceous, ceruminous, and mammary glands. Sudoriferous glands produce sweat and genital secretions. Ceruminous glands produce ear wax. Sebaceous glands produce an oily substance called sebum. Mammary glands are the milk-producing glands that become active after a baby is born. 

Signs Something Could Be Wrong with Your Integumentary System

Because it is exposed to outside forces, the skin is vulnerable to injury, allergic reactions, or infection. Signs of skin problems frequently include pain, bleeding, itching, swelling, redness, or blistering. If you are concerned about an injury or unusual reaction affecting your skin, seek medical help right away. 

Minor cuts, scrapes, and bruises are common and usually heal without a problem. More serious skin injuries may need medical attention, though. Significant cuts may require stitches to help the edges of the wound come back together to heal. Serious burns require careful treatment with appropriate topical medicine and dressings. Rashes and itching can be the first signs of a serious allergic reaction that requires immediate care. Bruising may be an indication of a significant injury to the muscles or bones beneath the bruised skin. 

What Conditions Affect the Integumentary System?

In addition to the risk of injury or infection, the integumentary system can be affected by various health conditions. 

Skin conditions: Skin can develop chronic conditions such as eczema or psoriasis. These conditions are linked to the autoimmune system, and symptoms include skin changes. Eczema looks like a red, flaky rash that can be very uncomfortable. Psoriasis leads to skin lesions that are unsightly and may cause itching. Skin can also develop acne, often as the result of overproduction of oil and keratin in the hair follicles. This leads to raised blemishes on the skin. Skin is also vulnerable to cancer, often due to exposure to UV rays. 

Hair conditions: Hair loss is a common issue. For some people, hair loss is related to age and genetics and not the sign of an underlying condition. In other cases, people develop hair loss as a primary symptom. This is called alopecia, and doctors cannot always identify a cause. Hair loss can also develop as a side effect of some medications, such as drugs commonly used to treat cancer. 

Nail conditions: Fingernails and toenails can develop irregular growth patterns. This may be due to an underlying condition such as anemia or an injury to the nail bed. Nails can also develop fungal infections that cause the nails to look discolored and brittle. Contact your doctor if you notice unexplained changes to your nails.

Gland conditions: The glands in the integumentary system can develop chronic conditions. Seborrheic dermatitis is a condition where the sebaceous glands around hair follicles of the scalp produce excess sebum. This leads to oily build-up on the scalp, causing greasy scales or dandruff. Sweat glands can also become overactive and lead to the overproduction of sweat. This condition is called hyperhidrosis, and it can be a nuisance. Talk to your doctor about treatment for excessive sweating or seborrhea dermatitis. 

How Can You Keep the Integumentary System Healthy?

You can protect your integumentary system by maintaining good health habits and avoiding injury whenever possible. Some practices that protect skin and the other integumentary systems include:

  • Maintaining good hygiene
  • Practicing good skincare habits, such as using gentle products to wash and moisturize
  • Using sun protection
  • Wearing clothing that doesn't cause irritation
  • Getting regular checkups

If you have any questions about your skin health or other aspects of your integumentary system function, call your doctor. 

Show Sources

SOURCES:

Cleveland Clinic: “Integumentary System.”

Kim JY, Dao H, “Physiology, Integument,” StatPeals Publishing, January 2022.

Oregon State University: "Functions of the Integumentary System."

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