The skin is the covering that covers our body and that of all vertebrates: in man it represents the widest organ of the body and carries out essential tasks for the correct functioning of the human body.

Function of the skin What is it for?

Extremely flexible, the skin allows all of our movements while at the same time protecting our body from external threats. This is, in fact, the first function of this organ: acting as an anatomical barrier, our skin protects against any pathogenic or harmful agent from the world around us.

Another function, then, is found in the regulation of body temperature: it is through the skin that the body maintains its stable temperature in an optimal way, in order to preserve the functioning of all the processes of human-machine life.

In addition, one must not forget the sensitivity: it is through the skin and the receptors contained in it that man can “feel” and “touch” the world in which he lives. Through thermal receptors, we can perceive thermal variations by understanding, for example, when an object is hot or cold; Through pressure transducers, we can perceive pressure and, through algae sensors, vibrations and painful sensations, fundamental to our own survival.

Structure of the skin:

The skin has three layers:

•  Epidermis

•  Dermis

• Fatty layer (also called subcutaneous layer)

Each layer carries out specific tasks.

Structures under the skin:

The skin has three layers. Beneath the surface of the skin are fibers and nerve endings, glands, hair follicles, and blood vessels.

1 • Epidermis

The epidermis is the relatively thin and durable outer layer of the skin. Most of the cells in the epidermis are keratinocytes. These originate from cells in the deepest layer of the epidermis called the basal layer. New keratinocytes slowly migrate upward in the direction of the surface of the epidermis. When the keratinocytes reach the surface of the skin, they gradually fade and are replaced by new lower cells.

The outermost part of the epidermis, known as the corneal layer, is relatively impermeable and, when undetected, prevents most bacteria, viruses, and other foreign substances from entering the body. Additionally, the epidermis (along with other layers of the skin) protects internal organs, muscles, nerve fibers, and blood vessels from trauma. In certain areas of the body that require greater protection (such as palms and feet), the outer layer of the keratin epidermis (corneal layer) is much more common.

Spread throughout the basal epidermal layer, cells are called melanocytes, which produce melanin pigment, one of the main contributors to skin color. However, melanin’s main function is to filter ultraviolet radiation from sunlight (an overview of sunlight and skin damage), which damages DNA and causes numerous adverse effects, including skin cancers.

In addition, the epidermis contains Langerhans cells, which belong to the skin’s immune system. Although they help detect foreign substances and protect the body from infection, these cells also play a role in the development of skin allergies.

2 • Dermis

The dermis, the underlying layer of the skin, is a thick layer made up of elastic and fibrous tissue (consisting essentially of collagen, elastin, and fibrillin), which gives the skin its flexibility and strength. The dermis contains nerve endings, sweat glands and oil glands, hair follicles, and blood vessels.

Nerve endings perceive painful, tactile, pressurized, and thermal sensations. Some areas of the skin are richer in nerve endings than others. For example, the toes and feet contain many nerve fibers and are extremely sensitive to touch.

The sweat glands produce sweat in response to heat and stress. Sweating is made up of water, salts, and other chemicals. Evaporating from the skin, it allows cooling. The specialized sweat glands located in the armpits and genital regions (apocrine of the sweat glands) secrete a thick, oily sweat that, when digested by skin bacteria present in these areas, produces a distinctive body odor.

The sebaceous glands secrete sebum into the hair follicles. Sebum is an oily substance that gives skin smoothness and shine and acts as a barrier to external substances.

Hair follicles produce the various types of hair throughout the body. Hair not only contributes to the appearance of an individual, but also fulfills a number of important physiological functions, such as regulating body temperature, protection against injury, and increased sensitivity. A part of the follicle also contains stem cells that can regrow damaged epidermis.

Blood vessels in the dermis provide nutrients to the skin and help regulate body temperature. The heat causes an increase in the diameter of the blood vessels (dilation), allowing large amounts of blood to circulate near the surface of the skin where it can be released. The cold causes a decrease in the diameter of the blood vessels (restriction), which allows the body not to disperse the heat.

Different parts of the body contain a variable number of nerve endings, sebaceous and sweat glands, hair follicles, and blood vessels. For example, the head is covered by many hair follicles, while the feet are not.

3 • Capa adipose

Beneath the dermis is a layer of fat that helps insulate the body from heat and cold, provides a protective padding, and serves as storage for energy reserves. Fat is contained in living cells defined as adipose cells (adipocytes), held together by fibrous tissue. The adipose layer has a variable thickness, of a fraction of centimeters. for example in the eyelids up to several centimeters, for example in the abdomen and buttocks of some people.

Samantha Robson
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Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of ​​expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.

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