Structure and Function of the Skin – Function of the Skin and Skin Layers

The skin consists of the epidermis, the dermis (also known as the corium), and the subcutis.

The Epidermis

The epidermis is the outermost, keratinizing layer of squamous epithelium. It consists of multiple layers. On the surface, it terminates outwardly with the stratum corneum (the so-called horny layer). The stratum corneum prevents the penetration of pathogenic microorganisms such as bacteria, viruses, and fungi. It is particularly thick in areas subject to heavy mechanical stress, such as the soles of the feet, heels, or palms of the hands, which is why these areas are also referred to as calluses.

Beneath the stratum corneum lies the basal layer. New cells are continuously formed here (regeneration). These migrate outward to the surface and gradually keratinize there until they are shed as dead skin cells.

The deeper cell layers of the epidermis contain the pigment-producing cells—known as melanocytes. These cells determine skin type through the melanin they produce, a black-brown pigment. The epidermis also contains Langerhans cells. These play a significant role in the skin’s immune response.

The Dermis

The dermis consists of a network of strong collagen and elastic fibers. In the upper layers are structures called papillae, which extend into the epidermis and thus interlock the epidermis and dermis.

The dermis contains the majority of the skin’s sensory organs. These include, among others, Meissner’s corpuscles, which are responsible for the sense of touch and tactile sensation, as well as free nerve endings for pain perception. While the epidermis has no blood vessels, the dermis contains many fine capillaries that play a key role in regulating body temperature.

The Subcutaneous Tissue

The subcutaneous tissue consists of loose connective tissue rich in adipose tissue (subcutaneous fat). Its development varies greatly from person to person and from region to region, and it primarily serves as a fat reservoir. The subcutaneous tissue also connects the skin to the body’s fascia (connective tissue sheath) that covers the muscles.

The hair follicles

Hair consists of strong yet flexible keratin filaments. It is located in an epidermal follicle, through which it extends into the subcutaneous tissue. The lower part of the hair shaft features a bulge (hair bulb) that sits atop a connective-tissue hair papilla (growth zone).

Melanocytes are also located at this site; they produce pigment and deposit it into the hair. On either side of the hair shaft are hair follicle glands and sebaceous glands. These secrete an oily substance that keeps the hair supple and protects the hair and skin from germs (bacteria).

Other Glands of the Skin

In addition to the sebaceous glands, the skin has sweat and scent glands. The sweat glands, which consist of a cluster of glands, are located in the transition zone between the dermis and the subcutaneous tissue. They have a long excretory duct that leads to the skin’s surface.

Together with sweat, the sweat glands produce an acidic secretion that inhibits the growth of bacteria on the skin’s surface (= acid mantle). Sweat consists primarily of salts. However, metabolic waste products such as urea, uric acid, ammonia, and metabolized medications are also excreted in sweat.

Furthermore, the sweat glands play a significant role in temperature regulation. The scent glands are located in the skin of the armpits, as well as in the scalp and pubic region. These glands occur in larger clusters and secrete an alkaline substance during puberty. 

Skin Receptors

The skin contains various receptors for perceiving stimuli: 

• mechanical stimuli (mechanoreceptors)
• Temperature (thermoreceptors)
• Pain (nociceptors)

The stimuli detected by mechanoreceptors, thermoreceptors, and nociceptors are converted into so-called action potentials and transmitted along the nerve fibers. In this process, the stimuli from a strip of skin always reach the segment of the spinal cord assigned to them. Find a specialist for your condition. 

The mechanoreceptors

Mechanoreceptors mediate a large part of surface sensitivity, such as the perception of touch, pressure, tickling, and vibration. Mechanoreceptors are located in different layers of the skin and have varying structures. Mechanoreceptors include:

• Merkel discs in the deepest layer of the epidermis: They are responsible for pressure sensation and transmit impulses to the brain in response to light pressure.
• Meissner’s corpuscles in small protrusions (papillae) of the dermis: They are found particularly in the fingertips and, as organs of the sense of touch, are also responsible for the perception of pressure.
• Vater-Pacini corpuscles in the subcutaneous tissue: These relatively large mechanoreceptors transmit sensations of vibration.
• Nerve networks (dendrites) around the hair follicles detect touch.
• Free nerve endings in the dermis (some extending into the epidermis): They detect strong, sharp stimuli in particular.

Thermoreceptors

Thermoreceptors are found as free nerve endings in the skin and within the body. Their density is much lower compared to that of mechanoreceptors. They are classified as cold and warm receptors. They contribute to the body’s temperature sensing and regulation.

Nociceptors (pain receptors)

Nociceptors, as free nerve endings, are responsible for the sensation of pain. Superficial pain, in particular, is transmitted via the skin. In general, any environmental factors that lead to tissue damage can trigger a pain stimulus. These include, above all, mechanical stimuli (such as cuts), but also high temperatures (destruction of body proteins at 45 °C and above) and chemical substances (such as acids).

As an interface and protective barrier between the body and the environment, the skin performs a number of functions. These include:

Sensory function: Thermal and mechanical stimuli, as well as pain, are perceived through the skin via a variety of receptors.

Protective function: The skin provides passive protection for the body against potentially harmful environmental influences. These include, in particular, heat, cold, impact, pressure, friction, and radiation. In addition, it provides active protection through its role in the immune system.

Storage organ: The skin stores adipose tissue and thus serves as an important energy reserve.

Thermoregulation: The skin maintains thermal balance by constricting or dilating its blood vessels. It is thus involved in regulating body temperature and circulation. When the outside temperature is high, the small blood vessels dilate, and the skin—which is now better supplied with blood—warms up.

This releases heat into the cooler outside air. In colder temperatures, however, the fine blood vessels constrict. Less heat is released into the outside air, and heat loss is reduced.

Excretory function: Through the secretion of various substances, such as sebum and sweat, water, salt, and metabolic waste products are excreted through the skin. At the same time, the skin plays a role in regulating the body’s water and salt balance.

For issues such as allergies, it is advisable to consult a professional counseling center or a specialist. 

Skin conditions (dermatoses) are treated by a dermatologist. Among the most common conditions are:

• Athlete’s foot
• Acne
• Pigment disorders such as freckles, age spots, or vitiligo
• Excessive sweating (hyperhidrosis)
• Benign skin tumors such as atheromas (sebaceous cysts), seborrheic keratosis (age spots), port-wine stains, or moles
• Allergic contact dermatitis (hypersensitivity reaction of the skin to metals, preservatives, fragrances, dyes, or latex)
• Atopic dermatitis (a chronic inflammatory skin condition that usually occurs in flare-ups, characterized by itchy and reddened areas of skin) 
• Psoriasis
• Warts (skin infection caused by human papillomaviruses)
• Herpes infections (cold sores, chickenpox, shingles, finger herpes)

Atopic dermatitis © Gina Sanders / Fotolia

The skin is the largest organ in the human body and performs vital functions for the body. The structure and function of the skin demonstrate that it is the body’s largest organ and consists of three layers that work together to protect the skin.

The anatomy of the skin—including the epidermis, dermis, and subcutis, as well as the stratum papillare—highlights its complex structure, in which blood and lymph vessels, as well as nerve cells, perform important functions. The skin protects the body from external influences, while sweat and sebaceous glands, as well as skin appendages, stabilize the pH level and prevent the skin from drying out.

Keratin and corneocytes strengthen the barrier, while pigment and increased melanin influence the skin’s appearance and its protection against UV radiation. Depending on the body region and skin type—such as sensitive or dry skin—the skin reacts differently to stressors and potential damage.

Overall, it is evident that the skin’s function is to protect itself and the body; thus, healthy skin is crucial for the balance of the entire organism.

What is the structure and function of the skin?

The structure and function of the skin involve three layers: the epidermis, dermis, and subcutis. The epidermis forms the stratum corneum, while the dermis contains blood vessels, sebaceous glands, and sweat glands. The subcutis consists of fatty tissue and provides mechanical protection for the body.

What is the function of the skin?

The function of the skin is to protect the human body from environmental influences, UV radiation, and pathogens. In addition, it regulates body temperature through sweating and serves as a sensory organ.

Why is the skin the largest organ?

The skin is the body’s largest organ because it covers the entire human body. It protects the body, stores fat tissue, and responds to external influences.

What are the layers of the skin?

The skin consists of three layers: the epidermis, the dermis, and the subcutis. These layers perform different roles in the structure and function of the skin.

How does the skin protect the body?

The skin protects the body through the stratum corneum, sebum, and sweat and sebaceous glands. It prevents the entry of bacteria, reduces water loss, and protects against harmful UV radiation.