Integumentary System: Function, Parts, and Main Organs

2.4.2025 0 comments

Author: Trisha Houghton

The integumentary system is an absolutely crucial system that protects your body from outside threats.

It’s quite literally the first line of defense against invading pathogens and possible injuries, pollutants and solar radiation.

When it’s weakened or compromised, it can break down and age quickly. Keeping your integumentary system healthy and functioning at optimum capacity will prevent accelerated aging both inside and out.

In this article, we’re going to take a deep dive into the integumentary system. We’ll look at what it is, what it does, and what the parts of the skin system are. We’ll also examine what the role of the integumentary system is—not just for external protection, but also contributing to the rest of your body’s functions.

We’ll explore common disorders of the integumentary system and discuss what you can do to keep this critical system healthy.

Introduction to the Integumentary System

The integumentary system is the largest organ system in the human body. Its primary function is to protect the body from outside threats of all sorts.

The main organ in the integumentary system is the skin. Your skin covers a surface area of nearly 20 feet and serves as an exterior “shell” to shield your internal organs and systems from physical damage, disease, pollution, and UV radiation.

Working in tandem with your skin are your hair, nails, and the exocrine glands that produce sweat and an oily substance called sebum.

However, as you’ll see below, the skin and integumentary system aren’t only about protecting your insides. It also serves a number of very important bodily functions.

Primary Functions of the Integumentary System

The integumentary system plays a huge role in protecting the body while supporting several essential physiological functions. It works continuously to maintain balance between the external environment and internal systems.The integumentary system also plays a crucial role in collaborating with the immune system to defend against pathogens and with the circulatory system to regulate temperature and nutrient delivery.

Below are the main functions of the integumentary system that you need to know about.

Protection

The skin, hair, nails, and exocrine glands serve the primary function of protecting your body from outside threats. This may include impacts with foreign bodies, falls, flying objects, invading pathogens, and UV radiation.

Your skin is the first line of defense against all threats. There are antimicrobial peptides and lipids (fatty acids) on your skin that serve as a biomolecular barrier to disrupt bacteria, viruses, and fungi from penetrating to the tissues beneath.

Immune cells in your skin (both lymphoid cells and myeloid cells) provide active defense against pathogens, too. These cells travel to potential infection sites to attack the pathogens attempting to invade your skin.

The skin forms a highly resilient barrier that is self-repairing and self-restoring, ensuring your outer protection is always operational. It produces antimicrobial peptides and lipids that actively combat bacteria, viruses, and fungi. These biomolecular barriers play a significant role in preventing infections by disrupting the outer layers of invading pathogens.The skin even orchestrates the wound healing process. It triggers inflammation, remodeling, cellular proliferation, and hemostasis to make repairs in the cases of injuries or accidents.

Regulation

The skin also serves the very important function of regulating your body temperature and cell fluid maintenance. It controls heat by dilating blood vessels to release excess warmth or constricting them to retain heat.

Sweating also helps to maintain body temperature. Sweat glands in the skin release sweat onto the surface of your skin, where the water component of the sweat evaporates and cools your skin.

Sensation

Every inch of skin is home to sensory nerve endings that respond to sensations, including touch, pain, and temperature.

The skin is one of the most sensitive parts of your nervous system because one of its primary functions is to detect potential sources of danger (or pleasure). Electrical signals travel from your skin’s nerve endings, up your nerves, and through your spinal column to your brain, where they are registered as “sensations”.

Excretion

Sweating serves the dual purpose of cooling your body and excreting waste.

Sweat is made up of not only water, but substances like sodium chloride, urea, fatty acids, and lactic acids. These substances are excreted to maintain homeostasis in the body.

Sweat can also excrete toxins that are absorbed into the skin via solar radiation, pollution, or physical contact with toxic substances.

Vitamin D Synthesis

When the skin is exposed to UVB sunlight, a compound in the epidermis called 7-dehydrocholesterol is converted into Vitamin D3 (cholecalciferol). This inactive form is transported to the liver, where it becomes calcidiol. Calcidiol is then processed in the kidneys into the active hormone calcitriol, which regulates calcium absorption, bone health, and immune function.

The functions of Vitamin D3 include: 

• Promoting calcium absorption in the intestines;
• Maintaining blood calcium levels;
• Facilitating the production of new bone tissue;
• Regulating muscular contractions;
• Combating the growth of cancer cells.

Vitamin D is one of the most important vitamins in the human body, and it’s produced exclusively by the skin as a result of exposure to sunlight.

Water Retention

The skin acts as a moisture barrier to trap fluids inside the body to prevent excessive water loss.

Oils on the surface of your skin form a water-impermeable shield that prevents external water, which may be contaminated, from absorbing into your skin. This barrier also stops internal water—essential for muscle contraction, blood supply, and thermoregulation—from draining out or evaporating due to heat and sunlight exposure.

Your skin is crucial for maintaining a healthy fluid balance inside your body. It also shows you when you aren’t consuming enough water. Dehydration can lead to dry, cracked, and flaking skin.

Main Parts of the Integumentary System

The integumentary system is made up of several interconnected parts that work together. Each component plays a specific role in defense, sensation, and regulating important bodily functions.

Skin

The skin is the largest organ in the integumentary system—and the human body. It covers around 20 square feet of surface area and weighs around 10 pounds in total.

The skin is made up of multiple layers.

The epidermis (or epidermal layers) is the outermost layer created chiefly from keratinocytes, along with melanocytes and other skin cell types.

The layers of epidermis include:

• Stratum basale;
• Stratum spinosum;
• Stratum granulosum;
• Stratum lucidum;
• Stratum corneum.

These skin layers comprise the epidermis, the outer layer that serves as your body’s first line of defense against external threats. Stem cells located in the basal layer of the epidermis produce new skin cells to continually regenerate the surface of your skin. There are no blood vessels in the epidermis, but all the nutrients it receives comes from the dermis below.

The dermis houses the nerve endings, blood vessels, glands, and hair follicles. The dermis is made up of connective tissue in a “framework” that supports the epidermis while also making space for the other skin structures.

The dermis is formed of two layers: the superficial papillary dermis and the deep reticular layer.

Beneath the dermis, the last line of skin is called the hypodermis. Also called “subcutaneous tissue”, the hypodermis is an underlying connective tissue framework formed of both adipose tissue and loose areolar tissue. It provides cushioning, insulation, storage for fat cells, and connects the skin to the muscles, joints, and other structures below.

Hair

Hair is a critical component of the integumentary system.

It serves as a line of defense against solar radiation, cold, and damage. It also provides important sensory functions. It’s even an external reflection of your interior health (poor nutrition can cause poor hair health). Both hair and nails are composed of keratin, a tough protein that provides structural integrity. This keratin barrier protects against environmental damage and supports the overall health of the integumentary system.

There are two types of hairs:

• Terminal hairs, the longer, thicker, and more heavily pigmented hairs that grow longer and are easily visible. Most of the visible body hairs are terminal hairs.

• Vellus hairs, the shorter, narrower, and more lightly pigmented hairs. These are typically called “peach fuzz” and cover most of the surface of the human body. Many vellus hairs don’t project beyond their follicles in many areas.

Hair Follicles

The hair follicles, located in the middle dermis layer of skin, are cylindrical tubes that anchor your hair to your skin. The open hole at the top allows the hair to grow out of the hair shaft, and the base contains the bulb (root) of the hair. It’s these roots that provide the sensory input from your hair and produce the new cells to stimulate hair growth.

Hair follicles also contain the sebaceous glands (see below).

Nails

Nails are protective structures made of keratin scales (squames) that reinforce and support the fingers and toes. Nails protect these sensitive areas from physical injury and damage caused by harmful particles in the environment.

Beneath the nail lies the nail bed, supported by dense connective tissue, which anchors the nail and ensures proper growth. Changes in nail appearance, such as nail discoloration, can signal underlying health issues, making nails not only protective but also indicators of overall health.

Sweat Glands

Sweat glands in the skin help regulate body temperature and remove waste from the body. They also work alongside lymph vessels to maintain fluid balance and support the body’s natural detoxification process.

There are two types of sweat glands:

• Eccrine glands, which are found all over your body. Their primary role is thermoregulation.

• Apocrine glands, which are typically found in areas like the armpits, around the breasts, and the groin. These activate during periods of intense stress or heightened arousal, and are typically more active during puberty.

While eccrine glands are more widespread, apocrine glands tend to function more frequently throughout the day. Eccrine glands, found throughout the body, secrete sweat directly onto the skin surface to aid in cooling.

In contrast, apocrine glands, located in areas such as the armpits and groin, secrete a thicker sweat into hair follicles, often activated by stress or hormonal changes.

Both gland types are essential for managing body heat and eliminating waste.

Dysfunction in either type can lead to issues such as excessive sweating, which can disrupt temperature control and impact daily comfort.

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Mammary Glands

The mammary glands are specialized glands within the integumentary system responsible for producing milk after childbirth. These glands are embedded in a fatty layer of tissue within the breasts, which provides protection and structural support.

Milk production involves the release of secreted organic substances, such as proteins, fats, and antibodies, that nourish and protect the infant.

Sebaceous (Oil) Glands

Sebaceous glands produce skin oil, which is excreted to protect the skin, keep it lubricated, and eliminate dead skin cells and other waste tissue cells from the skin.

The skin oils produced in the hair follicles also form the moisture barrier that keeps water locked inside your skin to maintain moisture. These glands secrete protective films that shield the skin from bacteria and environmental damage.

Similarly, specialized glands in the ears produce ear wax to trap dust, debris, and harmful particles.

Nerves and Blood Vessels

In the dermal layers of the skin, nerves provide sensory input to the brain, while blood vessels deliver essential nutrients and oxygen to the skin. These blood vessels also dilate and constrict to regulate body temperature.

The density and sensitivity of each nerve fiber varies across different areas of the skin, making some regions more responsive to touch, pressure, pain, and temperature changes. This complex network allows the skin to protect the body while responding to environmental stimuli.

How the Integumentary System Works

The integumentary system includes your skin, hair, and nails that all work together to shield the body from external threats. It’s the first line of defense against bacterial and fungal infection as well as damage. Skin protects the soft, easily damaged internal organs.

When the body undergoes trauma (burns, cuts, skin infections, etc.), stem cells located in the lower layers of skin trigger the production of new skin cells to regenerate the outer protective layer.

The blood vessels and sweat glands in the skin work together to store or release heat in order to maintain a stable internal temperature despite the changing temperature of the outer environment.

Nerve endings in the skin detect changes in the environment and transmit those signals to the brain.

Melanocytes in the skin and hair also produce melanin, the pigment cell that provides protection for your skin against damage from the UV rays in sunlight. The more melanin your skin produces, the more you are shielded from solar radiation.

Common Integumentary System Disorders

The integumentary system is vulnerable to various disorders that can affect the skin, hair, nails, and glands. These conditions can disrupt the body’s protective barrier, impact appearance, and interfere with essential functions of the body.

The next sections will list some of the most common diseases of the integumentary system.

Acne

Acne is a skin condition that occurs when skin oils mix with dead skin cells and clog up the hair follicles. A clogged hair follicle can become inflamed and infected (the result of the P. acne bacteria present on the human skin) and lesions (called “zits” or “pimples”) form.

Acne most commonly forms on the face, but it can also form on the shoulders, back, and chest. It’s most common among teenagers (due to higher skin oil production) but can persist even into adulthood.

An increase in hormones is the most common cause of acne, but risk factors include age, certain medications (like corticosteroids or lithium), and a family history of acne problems.

Eczema

Atopic dermatitis, also called “eczema”, is dry, inflamed, and itchy skin. It’s often a chronic condition that is common to young children but can crop up at any age anywhere on the body.

Symptoms of eczema include:

• Thickened skin;
• Oozing and crusting;
• Small raised bumps;
• Rashes;
• Swollen skin;
• Dry and cracked skin;
• Itchiness;
• Skin turning sensitive and raw from excess scratching.

In some cases, eczema results from some genetic issue that compromises the skin’s ability to protect itself and regulate skin oil production and hydration. It’s also likely to be caused by irritants (including allergens and environmental factors).

However, it may also be caused by high levels of the Staphylococcus aureus bacteria on the skin, which can kill off or weaken beneficial bacteria critical for maintaining the skin’s moisture barrier.

Psoriasis

Psoriasis is a skin condition that typically appears on the scalp, knees, trunk, and elbows in the form of scaly and itchy skin patches.

Psoriasis is believed to be an immune system issue that causes the body to attack its own healthy skin cells. This attack triggers faster-than-average growth of skin cells in an effort to repair the damage. The accelerated cellular turnover contributes to the scaly and dry patches.

Skin Cancer

Basal cell carcinoma, melanoma, and squamous cell carcinoma are the three skin cancer types to be aware of.

Typically, these cancers form on areas of skin that are exposed to the sun: your face, neck, scalp, hands, arms, chest, etc. However, they can form beneath your finger and toe nail plate (on the skin that forms the nail bed), on your genitals, and other places that receive little to no sunlight exposure.

Skin cancer is the result of mutations in your skin cells’ DNA. The DNA mutations cause the skin cells to multiply out of control, and they clump together to form cancerous cell clusters.

Most skin cancers begin in the epidermis but can spread to the dermis and throughout the body if left untreated.

Alopecia

Alopecia, or hair loss, can be caused by hormones reducing the function of hair follicles (male pattern baldness) or immune system malfunction leading your body to attack its own hair follicles (alopecia areata).

The hair loss may be in a pattern, at random places throughout the body, in large patches, or even total.

Burns

Burns are wounds caused by energy (chemical, thermal, electromagnetic, and electrical) damaging the skin.

There are several different degrees when it comes to burns:

• First-degree burns only damage the outermost epidermal layers, and though painful, are typically not too serious.
• Second-degree burns damage the epidermis and part of the dermis beneath.
• Third-degree burns destroy the epidermal layers and dermis beneath, potentially damaging even the subcutaneous layer and the bones, muscles, and loose connective tissue beneath (typically referred to as “fourth-degree burns”).

Minor burns can be easily treated and may not inflict long-term damage on the skin. More severe burns can be devastating, debilitating, or even fatal.

Maintaining Integumentary System Health

Your skin and the rest of your integumentary system needs you to look after it, to take simple actions every day to keep it healthy.

Try the following:

• Step up your skincare routine. Use moisturizers that infuse nutrients and moisture into the skin and provide additional oils to strengthen the moisture barrier. Wash your skin regularly to scrub away dead skin cells and excess skin oils.
• Improve your diet. Eat more foods rich in Vitamins A, C, and E, all of which are crucial for healthy skin, hair, and nails. Focus on foods rich in omega-3 fatty acids (e.g.,chia seeds, walnuts, flaxseed) to reduce inflammation, zinc (e.g., pumpkin seeds, chickpeas) for skin healing, and selenium (e.g., Brazil nuts) for protection against oxidative damage.
• Drink more water. Increasing your water intake will ensure your skin stays hydrated, which is crucial for skin cell regeneration and staving off dryness.
• Protect your skin against the sun. Wear a hat and long-sleeved clothing (weather-permitting) to stop UV radiation from being absorbed into your skin. In summer, wear plenty of sunscreen. Use a broad-spectrum sunscreen with at least SPF 30, daily for sunny environments. When you are exposed to direct sunlight, reapply every two hours, especially during peak hours or when in water.

• Get yourself checked up. Yearly skin checkups will help you monitor any skin disorders and moles, freckles, or dark spots that have the potential to turn cancerous.

Your skin is capable of repairing and regenerating itself. You just need to give it a helping hand in small ways every day and it will stay healthy and strong.

Conclusion

There’s no doubt: the integumentary system is hugely important for your body. It not only shields your internal organs and tissues from damage, but also plays a role in sensation and body temperature regulation.

As you’ve seen, there are many working parts involved, and these parts are all prone to deterioration and degeneration as you age.

By following the simple steps we shared above to maintain your integumentary system health, you can keep your skin, hair, nails, blood vessels, nerve endings, and blood vessels functioning at optimum capacity to protect you from all outside threats.

FAQs

What are the functions of the skin system?

The skin—along with your hair, nails, sweat glands, skin oil glands, blood vessels, nerve endings, and other parts of the integumentary system—provides protection, thermoregulation, sensory input, immune response, and waste removal. It’s also crucial for Vitamin D synthesis, which is crucial for good bone health.

Is skin part of the immune system?

Yes, the skin is part of the immune system. It acts as a physical barrier to keep out pathogens, and resident immune cells living on the skin provide both adaptive and innate immune responses. The skin even has chemical barriers (in the form of bacteriostatic fatty acids) that attack bacteria upon contact.

How do you detox your integumentary system?

You can’t really detox your integumentary system. Very few toxins are excreted via the skin. However, regular washing, exfoliating, and using cleanser to eliminate bacteria, dead skin cells, and excess skin oils can reduce the risk of acne and other skin conditions. Good hydration and proper diet can also facilitate better skin health.

Resources

Integumentary System

Physiology, Integument

Integumentary System

Integumentary system

Skin as the site of vitamin D synthesis and target tissue for 1,25-dihydroxyvitamin D3

Hair Follicle

Acne

Atopic dermatitis (eczema)

Psoriasis

Skin cancer

Hair loss types: Alopecia areata overview

Burns and Wounds

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