Which Of The Following Is Not True Of The Surface Of The Skin?

The skin is the torso'south largest organ. Information technology serves many important functions, including

Protecting the body confronting trauma
Regulating body temperature
Maintaining h2o and electrolyte residual
Sensing painful and pleasant stimuli

The pare has three layers:

Epidermis
Dermis
Fat layer (also called the subcutaneous layer)

Each layer performs specific tasks.

Getting Under the Skin

The skin has 3 layers. Beneath the surface of the skin are fretfulness, nerve endings, glands, hair follicles, and blood vessels. Sweat is produced by glands in the dermis and reaches the surface of the skin through tiny ducts.

The epidermis is the relatively thin, tough, outer layer of the peel. Most of the cells in the epidermis are keratinocytes. They originate from cells in the deepest layer of the epidermis called the basal layer. New keratinocytes slowly migrate up toward the surface of the epidermis. Once the keratinocytes attain the pare surface, they are gradually shed and are replaced by newer cells pushed up from below.

The outermost portion of the epidermis, known as the stratum corneum, is relatively waterproof and, when undamaged, prevents most leaner, viruses, and other foreign substances from inbound the body. The epidermis (along with other layers of the peel) also protects the internal organs, muscles, nerves, and claret vessels from injury. In certain areas of the body that crave greater protection, such as the palms of the hands and the soles of the feet, the stratum corneum is much thicker.

Scattered throughout the basal layer of the epidermis are cells called melanocytes, which produce the pigment melanin, one of the primary contributors to pare color. Melanin'south primary function, however, is to filter out ultraviolet radiations from sunlight (see Overview of Sunlight and Skin Damage Overview of Sunlight and Pare Damage Sunlight stimulates vitamin D production, helps control some chronic pare diseases (such as psoriasis), and causes a sense of well-being. Notwithstanding, sunlight tin cause skin harm. Harm includes... read more Overview of Sunlight and Skin Damage ), which damages DNA, resulting in numerous harmful effects, including skin cancer Overview of Skin Cancer Skin cancer is the nearly common type of cancer. Skin cancer is almost common among people who piece of work or play sports outside and amidst sunbathers. Fair-skinned people are particularly susceptible... read more .

The epidermis likewise contains Langerhans cells, which are part of the skin'south immune system. Although these cells help detect foreign substances and defend the trunk against infection, they also play a function in the development of skin allergies.

The dermis, the skin's next layer, is a thick layer of fibrous and rubberband tissue (fabricated mostly of collagen, with a pocket-size merely important component of elastin) that gives the peel its flexibility and forcefulness. The dermis contains nerve endings, sweat glands and oil glands (sebaceous glands), hair follicles, and claret vessels.

The nerve endings sense pain, touch, pressure level, and temperature. Some areas of the skin comprise more than nerve endings than others. For example, the fingertips and toes contain many nerves and are extremely sensitive to touch.

The sweat glands produce sweat in response to heat and stress. Sweat is composed of water, salt, and other chemicals. Equally sweat evaporates off the pare, information technology helps cool the body. Specialized sweat glands in the armpits and the genital region (apocrine sweat glands) secrete a thick, oily sweat that produces a characteristic body odor when the sweat is digested by the pare bacteria in those areas.

The sebaceous glands secrete sebum into hair follicles. Sebum is an oil that keeps the pare moist and soft and acts equally a barrier against foreign substances.

The hair follicles produce the diverse types of hair establish throughout the trunk. Hair non only contributes to a person's appearance simply has a number of of import physical roles, including regulating body temperature, providing protection from injury, and enhancing sensation. A portion of the follicle besides contains stem cells capable of regrowing damaged epidermis.

The blood vessels of the dermis provide nutrients to the skin and help regulate body temperature. Heat makes the blood vessels enlarge (amplify), allowing large amounts of blood to broadcast almost the skin surface, where the estrus can exist released. Cold makes the claret vessels narrow (constrict), retaining the torso's heat.

Over different parts of the body, the number of nerve endings, sweat glands and sebaceous glands, hair follicles, and blood vessels varies. The top of the caput, for instance, has many hair follicles, whereas the soles of the anxiety have none.

Below the dermis lies a layer of fatty that helps insulate the body from heat and common cold, provides protective padding, and serves equally an energy storage surface area. The fatty is contained in living cells, called fat cells, held together by fibrous tissue. The fat layer varies in thickness, from a fraction of an inch on the eyelids to several inches on the abdomen and buttocks in some people.