How are you audience :-D? I am really ok, and ready... here I am with my second article. Today I want to talk about the skin, THE fantastic "dress" that we have supplied with the basic package ...
Let start with the scientific part :-P
The skin is the largest organ in the body.
Its main functions are:
Protection the body from trauma
body temperature regulation
Maintaining the hydroelectrolyte balance
pain and pleasurable stimuli perception
Contribution to the synthesis of vitamin D
The skin keeps inside the body nutrients and needed substances, in the main time it is also a barrier against dangerous substances and it is a screen versus the ultraviolet radiation from the sun.
The skin has three layers:
- Adipose layer (also called subcutaneous layer)
Each layer performs specific tasks.
The epidermis is the outer layer and relatively thin and resistant. Most cells in the epidermis are keratinocytes and they are produced in the underlying layers and over time they migrate to the surface. When the keratinocytes have reached the surface of the skin, they gradually break down and are replaced by new cells pushed from bottom to top.
It is relatively impermeable and, when "healthy", prevents the penetration of most bacteria, viruses and other foreign substances into the body.
The epidermis contains the Langerhans cells, which belong to the cutaneous immune system. Although they help to detect foreign substances and defend the body against infections, these cells also play a role in the development of skin allergies. Cells called melanocytes, which produce the pigment melanin, insteed, are found in the entire inner layer of the epidermis. The primary function of melanin is to filter ultraviolet radiation from sunlight
The dermis, is a thick layer, composed of elastic and fibrous tissue (consisting essentially of collagen, a small but important component of elastin), which gives the skin its flexibility and strength. The dermis contains nerve endings, sweat glands and sebaceous glands, hair follicles and blood vessels.
The nerve endings perceive the painful, tactile, pressure and thermal sensations. Sweat glands produce sweat in response to heat and stress. Sweat consists of water, salts and other chemicals. The sebaceous glands secrete sebum in the hair follicles. Sebum is an oily substance that gives the skin softness and shine and acts as a barrier against external substances. Hair follicles produce the various types of hair present throughout the body. The blood vessels of the dermis supply nutrients to the skin and contribute to the regulation of body temperature.
Under the dermis there is a layer of fat that helps to isolate the body from heat and cold, provides a protective fill and serves as a repository of energy reserves. Fat is contained in living cells called fat cells (adipocytes), held together by fibrous tissue. The adipose layer has a variable thickness, from a fraction of a centimeter at the eyelid level up to several centimeters on the abdomen and on the buttocks of some people.
The substances that are applied to the skin are mainly absorbed by diffusion, they pass between one cell and another one. The smallest, (now we talk about nanosomes) are able to reach the deepest layers but the majority of substances used in cosmetics remain mainly in the first layers of the skin, moisturizing, producing a protective film, stretching small wrinkles only at LOCAL level.
- Water: it "wet" the stratum corneum for a limited period of time.
- The famous silicones, vaseline, paraffins do not penetrate form an impermeable layer.
- Amino acids and water-soluble vitamins: they penetrate a small part both through the glands and through the epidermis, while a part remains on the surface but their function is moisturizing and protective.
- Vegetable oils and fat-soluble vitamins: oils penetrate according to their unsaturated fatty acids content and vitamins penetrate more easily if they are carried by oils.
- Essential oils: they penetrate easily and favor the penetration of some substances working as vehicles.
- Moisturizing and humectants: they moisten the stratum corneum and therefore have a moisturizing surface and protective action.
- New skin cells are continuously generated , so fast that every 28 years every human gets a new skin.
- On our skin flow up to 10 liters of sweat every day on the hottest days.
- Every square centimeter of skin contains up to 500 sensory corpuscles, which make it a real "detection device".
- It represents a sort of "antenna" that connects the body with the outside world.
Here, unfortunately we have reached the end. But see you soon