The integumentary system is a complex and vitally important organ system in the human body. It comprises the skin, hair, nails, and glands that produce sweat and oil.

These tissues work together to protect the body from infection and injury and regulate bodily processes. The skin is the first line of defense against the outside world and is responsible for keeping the internal organs safe and healthy.

It contains sweat glands that help fight overheating and dehydration by releasing sweat onto the skin’s surface. It also supports hair that provides insulation against cold weather and nails to help protect the tips of fingers and toes from injury.

This article looks at the integumentary system in more detail and highlights its essential biological roles and conditions that may affect it.

Person plays in fountainShare on Pinterest
Eduardo Parra/Europa Press via Getty Images

The integumentary system refers to the skin and its associated structures, including the following:

  • hair
  • nails
  • glands

As the largest organ in the human body, the skin has multiple functions. These include:

  • Protection: The skin and hair provide a barrier against harmful substances, ultraviolet (UV) radiation from the sun, and temperature extremes.
  • Sensation: The skin contains nerve endings that detect touch, pressure, pain, heat, and cold.
  • Temperature regulation: The skin can sweat and widen blood vessels to regulate body temperature.
  • Waste excretion: The skin eliminates some wastes through sweat.
  • Vitamin D production: When exposed to UV light from the sun, the skin produces vitamin D, which is important for bone health.

Skin

The skin is the body’s largest and heaviest organ. It covers the entire surface of the body and has multiple layers, each with different functions. It comprises three main layers:

  • The epidermis: This is the outermost layer of the skin. It is thin and constantly shedding dead skin cells.
  • The dermis: This is the middle layer of the skin. It contains blood vessels, nerves, hair follicles, and sweat glands.
  • The subcutaneous layer: This is the deepest layer of the skin. It comprises fat and connective tissue that attaches the skin to the underlying muscles. It insulates and cushions.

Its purpose is to protect the body from infection and injury, regulate body temperature, and eliminate waste. The skin is the first line of defense against infections from pathogens as it is a physical barrier and contains elements of the innate and adaptive immune systems.

Glands

Glands are functional units of cells that work in unison to release a substance, such as oil or sweat.

There are two types of glands in the body. Endocrine glands do not have a duct system and instead release their products directly into the bloodstream. In contrast, the skin houses various exocrine glands that have ducts to allow them to secrete substances to the epithelial surface.

These exocrine glands include:

  • Eccrine sweat glands: These simple, coiled, tube-like glands reside throughout the body. The sweat they produce is clear and has little to no oil or odor. Its purpose is to cool the body and remove waste by secreting water.
  • Apocrine sweat glands: These glands produce odorous perspiration. They are large, branched glands that typically appear in the armpits and genital area. They are not significantly involved in cooling.
  • Ciliary glands: These are modified apocrine sweat glands located in the eyelids. Their purpose is to lubricate the eye and keep it clean.
  • Sebaceous glands: These secrete an oily substance called sebum that moisturizes and protects the skin.
  • Ceruminous glands: These glands of the ear canal produce ear wax and are also modified apocrine glands. Ear wax is a sticky substance that protects the ear from water and foreign bodies. They
  • Mammary glands: There are two mammary glands on the front chest wall. In people assigned female at birth, the glands produce milk to feed babies.

Hair

Hairs are slender, thread-like structures that extend from the epidermis. They are composed of a protein called keratin and are usually pigmented, which gives them their color.

All areas of the body have hair, except for the palms of the hands and soles of the feet. Hairs protect against UV radiation, injuries, and extreme temperatures. They also play a role in sensation as they contain nerve endings that can detect touch, pressure, and temperature.

Nails

Nails are hard, protective structures covering the upper surface of the fingertips and toes. They are composed of a protein called keratin and grow from the base of the nail bed.

Nails protect the tips of the fingers and toes from injury and support fine motor tasks such as picking up small objects.

The skin, hair, nails, and glands work harmoniously to protect the body from harm and maintain homeostasis. The integumentary system works with the following bodily systems:

  • Immune system: Acts as a physical barrier to disease-causing germs and houses immune cells.
  • Digestive system: The skin provides the digestive system with vitamin D. This vitamin helps the body absorb calcium which is needed for bone maintenance and muscle contractions.
  • Cardiovascular system: The skin’s blood vessels can constrict or dilate to conserve or release heat.
  • Nervous system: The skin transmits information from sensations through nerve receptors to the brain. These include the perception of pain, heat, cold, and others.
  • Respiratory system: The tiny hairs lining the nasal passages remove harmful particles before the lungs inhale them.
  • Urinary system: The skin excretes waste products which helps the kidneys maintain the body’s electrolyte and pH balance.

Various conditions can affect the integumentary system.

Acne

Acne is a common condition that causes spots, pimples, and blackheads. It is most common in teenagers. However, it can occur at any age. Acne occurs when the pores of the skin become blocked with sebum, bacteria, and dead skin cells.

Athlete’s foot

Athlete’s foot is a fungal infection that causes itching, redness, and blisters on the feet. It is most commonly caused by wearing shoes that do not allow the skin on the feet to breathe.

Skin cancer

Skin cancer is the most common type of cancer. It can be due to overexposure to UV radiation from the sun or sunbeds. Skin cancer may appear as a discolored, scaly, and crusty skin patch.

Cold sores

A cold sore is a small, painful blister on the lips or around the mouth caused by the herpes simplex virus. Cold sores are contagious.

Psoriasis

Psoriasis is a chronic condition that causes the skin to produce new skin cells too quickly. This leads to the buildup of scaly, red, and itchy patches of skin.

Ringworm

Ringworm is a fungal infection that causes a ring-shaped rash on the skin. It is most common on the body, scalp, or feet and is contagious.

The integumentary system is composed of the skin, hair, nails, and glands. It works to protect the body from harm and maintain homeostasis by working with other bodily systems.

Various conditions can affect the integumentary system, including acne, athlete’s foot, skin cancer, cold sores, psoriasis, and ringworm.