Dorothy FarrarThe skin
The skin is the largest organ in the human body. The outer skin covers the entire surface of the body. As the boundary between the environment and the body, it forms an elastic and, above all, protective shell, but it also provides contact with the outside world.
Structure and function of the skin
The skin can be divided into three layers:
- the epidermis,
- the dermis and
- the hypodermis.
Epidermis
The upper skin (epidermis), consisting of the horny layer and the germ layer, is about as thick as a book page; at certain points of high mechanical stress it is even thicker.
Consisting of several cell layers, the lowest cell layer, the germ layer, constantly ensures the formation of new cells. Since regeneration depends on the available body energy, cell divisions take place in the first four hours after midnight, when the body requires less energy.
Excessive energy consumption during this time disrupts cell renewal. This high ability of the skin to regenerate is an advantage when it comes to harvesting the body’s own cells and in the case of many different injuries to the body’s surface. The epidermis can thus be constantly renewed.
Older cells of the germ layer gradually migrate to the surface of the skin and increasingly store a horny substance (keratin). They die there about four weeks after their formation and are finally shed as horny scales.
On the one hand, daily scaling distributes bacteria throughout the body and, on the other hand, prevents pathogens from penetrating. In addition, local bacteria form a barrier to ward off harmful microorganisms. They break down the sebum and thus lower the pH value of the skin with the resulting fatty acids. This protective acid mantle deters many types of bacteria. The horny layer consists primarily of horny, dead cells.
In the germ layer are branched cells containing dye, the pigment cells. They produce the pigment, melanin, which is released into overlying cells and protects the skin from burns when exposed to too much sunlight.
UV radiation in particular is dangerous for the body because it causes the connective tissue to age prematurely and disrupts the activity of the pigment cells. They are also able to change the genetic material of skin cells and thereby cause skin cancer. Overall, the epidermis protects the body from injury, dehydration , UV radiation and pathogens.
Dermis
A second skin layer is the dermis, which is about 2 mm thick and protrudes into the germinal layer with its bulges, the papillae. It consists of a dense network of elastic fibers that give the skin a firm, leather-like texture.
In addition, dermis cells, connective tissue cells, many nerves, muscle and sensory cells can be found here. Numerous blood vessels, arteries, veins and capillaries run through this skin layer and ensure a particularly strong blood flow.
Due to this fact, the epidermis is also optimally supplied with nutrients, hormones, vitamins and oxygen. In addition, the blood vessels in the skin play a key role in regulating our body’s temperature. With high heat production, these vessels dilate, so more blood flows through them and body heat is released to the environment in a controlled manner.
The papillae protrude into the epidermis in a wavy manner, creating a pattern of ridges and grooves. This skin ridge pattern is genetically determined, hereditary and therefore very specific. These so-called fingerprints, the skin ridge pattern of the fingertips, are therefore an unmistakable, individual characteristic of every human being. The skin ridge pattern is identical only in identical twins.
Components of the skin
In certain areas of the skin, toenails, fingernails and hair, which consist of horn and constantly grow back, were formed by the germ layer. Nails protect the ends of toes and fingers.
Hair is found almost everywhere on the body except for the palms of the hands, soles of the feet, and front phalanges. The hair develops at the bottom of an indentation in the germ layer in the dermis, the hair follicle. Right there is a small muscle that can straighten the hair in special situations (cold, stress ) (goosebumps).
Sweat and sebaceous glands
Sweat and sebaceous glands are embedded in the dermis, the ducts of which lead outwards through the epidermis and become visible as pores. The sweat glands secrete sweat through the pores , which contains dissolved metabolic waste products, salts, acids and water.
The blood ensures that all of these substances are transported smoothly. When the sweat evaporates from the skin’s surface, traces of acids remain, which together with the skin’s fat and dead skin cells form a protective acid mantle. This decisively prevents pathogens from colonizing the skin.
Sweat formation also serves to regulate body temperature, because when sweat evaporates on the body surface, heat is withdrawn from the organism in a controlled manner due to the evaporative cooling.
Through the sebaceous glands, the body excretes small amounts of sebum (fat), an oily mixture of wax, fatty acids, cholesterol, and dead cell material. The tallow coat provides the hair and fur of the animals with a waterproof cover and insulates the body from moisture and cold. However, we humans no longer need much sebum because we have other protective mechanisms (clothing), but our glands still produce it in abundance.
In addition to its insulating function, it binds skin moisture through its cover around dead cells of the callus and hair, makes the hair shiny and the skin supple. Sebum contains a chemical substance that, under the influence of UV rays from the sun, turns into vitamin D and plays a crucial role in bone formation (prevents bone softening, bone curvature, bone deformity). Also, sebum has the ability to kill certain harmful bacteria.
Hypodermis
The hypodermis: It consists mainly of loose connective tissue and fatty tissue, which can vary in thickness and serves as a storage depot for a large part of our body fat. The hypodermis thus forms an insulating layer that protects the body from excessive heat loss and acts as a cushion that can absorb pressure and shock.
Skin hazards
Dirt and sweat
Dirt and dust particles easily stick to the skin. In addition, components produced by the body itself accumulate on, for example, sweat, skin fat and sloughed off skin cells. Together they are an ideal breeding ground for bacteria, which are particularly found on the face, hands and feet, anus, genitals and armpits.
However, most bacteria are not pathogens. They break down sweat and sebum on the skin, the cause of an unpleasant odor. This happens primarily when the sweat cannot evaporate or be released due to high humidity in the environment or improper clothing.
The decomposition products of the bacteria can cause redness, the skin can become sore and cracked. Pathogenic bacteria can then easily enter the body at such points and cause inflammation.
Water
Staying in water for a long time also damages our skin, since the protective acid mantle can be destroyed and the horny layer swells. Pathogens, foreign bodies and other pollutants can quickly penetrate into the deeper layers of the skin and cause inflammation.
Parasites (lice, mosquitoes, ticks)
Lice, mosquitoes and ticks live as parasites on other living things. Human lice (head and pubic lice) colonize human skin and feed on their blood. Head lice prefer the scalp, pubic lice are very common in the genital hair. They cause severe itching and sometimes transmit dangerous diseases.
Acne
Acne can occur under the influence of hormones during puberty, especially on the face, chest and back. The sebaceous glands, the actual culprits, produce more skin fat during this time due to increased hormone activity and at the same time the skin becomes horny.
Dead skin cells collect in the ducts of the sebaceous glands and around the hair roots, mix with the sebum and form plugs that impede the drainage of sebum. Bacterial germs from neighboring sebaceous glands are added; they release agents that form acidic irritants and pus.
The pus seeps into the dermis and inflames the spot there – a pus pimple develops. There is increased formation of blackheads, which can develop into inflammatory and suppurating pimples, known as acne .
A lack of cleanliness can promote the development of this disease. Skin care starts with cleansing the skin and that means once a day one should cleanse the entire body with warm water and mild soap to successfully remove dust, dander, sweat and bacteria. However, the use of soap also destroys the protective acid mantle of the skin, which can be renewed within the next half hour.
Hello and welcome to my Health Guide & Encyclopedia! My name is Dorothy Farrar, and I'm the founder and main author of this platform.
My passion for health and wellness started at a young age when I became interested in the connection between the food we eat and the way we feel. This fascination led me to study nutrition and dietetics in college, where I learned about the importance of a balanced diet and the impact of various nutrients on the body.