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Human Skin Conditions and Diseases

Updated/Revised Date: 2022-04-11
Author: Disabled World | Contact: Disabled World (
Additional References: Skin Conditions Publications

Synopsis: General information on human skin conditions. Includes the basic functions and purpose of skin, as well as listing diseases and infections that can affect it. Human skin is composed of three primary layers consisting of the epidermis, dermis, and hypodermis. The average human adult skin has a surface area of 1.5 - 2.0 square meters (16.1 - 21.5 sq ft.), most of it between 2 - 3 mm (0.12 inches) thick.


Main Document

What Exactly is Skin?

In humans, skin is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals, except that it is not protected by fur.

Unclean skin favors the development of pathogenic organisms - the dead cells that continually slough from the epidermis mix with the secretions of the sweat and sebaceous glands and the dust found on the skin to form a filthy layer on its surface. If not washed away, the slurry of sweat and sebaceous secretions mixed with dirt and dead skin is decomposed by bacterial flora, producing a foul smell. Functions of the skin are disturbed when it is excessively dirty; it becomes more easily damaged, the release of antibacterial compounds decreases, and dirty skin is more prone to develop infections.

Because it interfaces with the environment, skin plays a critical role in protecting (the body) against pathogens. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B foliates. Severely damaged skin will try to heal by creating scar tissue. This is often discolored and de-pigmented.

Human skin is composed of three primary layers, consisting of the:


Provides waterproofing and serves as a barrier to infection. The epidermis contains no blood vessels, and cells in the deepest layers are nourished by diffusion from blood capillaries extending to the upper layers of the dermis. The main type of cells which make up the epidermis are Merkel cells, keratinocytes, with melanocytes and Langerhans cells also present.


Serves as a location for the appendages of skin. The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechano-receptor/nerve endings that provide the sense of touch and heat. It contains the hair follicles, sweat glands, sebaceous glands, apocrine glands, lymphatic vessels and blood vessels.


(subcutaneous adipose layer). The hypodermis is not part of the skin, and lies below the dermis. Its purpose is to attach the skin to underlying bone and muscle, as well as supplying it with blood vessels and nerves. It consists of loose connective tissue and elastin. The main cell types are fibroblasts, macrophages, and adipocytes (the hypodermis contains 50% of body fat).

Illustration shows the three primary layers of human skin; epidermis, dermis, and hypodermis.
Illustration shows the three primary layers of human skin; epidermis, dermis, and hypodermis.

Dermatosis (Plural dermatoses) is defined as "any disease of the skin," and, while thousands of skin disorders have been described, only a small number account for most visits to the doctor.

Skin Facts

See our list of skin diseases and conditions or find out other interesting facts regarding human skin.

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Subtopics and Associated Subjects

Latest Skin Conditions Publications
List of Skin Diseases and Conditions Article.
Comprehensive list of human skin conditions and diseases of the epidermis, dermis, and subcutaneous tissue that make up the skin.
Publish Date: 2020-04-08 - Updated: 2022-03-26
Fitzpatrick Scale Skin Type Test and Results Article.
Fitzpatrick skin type classification table denoting the six different skin types, colors, and reaction to UV sun exposure, includes self test to define your own skin classification.
Publish Date: 2020-01-17 - Updated: 2022-01-28
Leucoderma: White Spots or Patches on Skin Article.
Leucoderma, also called vitiligo, is a rare skin disease characterized by white spots and patches. The white patch or spot is called leucoderma, and when it occurs without any preceding disease it is called Vitiligo. Leucoderma is a symptom of vitiligo.
Publish Date: 2017-12-13 - Updated: 2021-10-28

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Disabled World provides general information only. The materials presented are never meant to substitute for professional medical care by a qualified practitioner, nor should they be construed as such. Financial support is derived from advertisements or referral programs, where indicated. Any 3rd party offering or advertising does not constitute an endorsement.

Cite This Page (APA): Disabled World. (2022, April 11). Human Skin Conditions and Diseases. Disabled World. Retrieved May 30, 2023 from

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