Skin Types
What is skin?
skin |skin|noun1 the thin layer of tissue forming the natural outer covering of the body of a person or animal : I use body lotion to keep my skin soft | a flap of skin.
The skin consists of three main layers: epidermis, dermis and subcutaneous tissue.
The skin is the largest organ in the body, comprising about 15% of the body weight. The total skin surface of an adult ranges from 12 to 20 square feet. In terms of chemical composition, the skin is about 70% water, 25% protein and 2% lipids. The remainder includes trace minerals, nucleic acids, glycosoaminoglycans, proteoglycans and numerous other chemicals.
The epidermis
The epidermis is the topmost layer of the skin. It is the first barrier between you and the outside world. The epidermis consists of three types of cells keratinocytes, melanocytes and Langerhans cells. Keratinocytes, the cells that make the protein keratin, are the predominant type of cells in the epidermis. The total thickness of the epidermis is usually about 0.5 - 1 mm. At the lowermost portion of the epidermis are immature, rapidly dividing keratinocytes. As they mature, keratinocytes lose water, flatten out and move upward. Eventually, at the end of their life cylce, they reach the uppermost layer of the epidermis called stratum corneum. Stratum corneum consists mainly of dead keratinocytes, hardened proteins (keratin) and lipids, forming a protective crust. Dead cells from stratum corneum continuously slough off and are replaced by new ones coming from below. The skin completely renews itself every 3 - 5 weeks. Most mild peels work by partly removing the stratum corneum and thus speeding up skin renewal.
Another significant group of cell in the epidermis are melanocytes, the cells producing melanin, the pigment responsible for skin tone and color. Finally, Langerhans cells are essentially a forepost of the immune system in the epidermis. They prevent unwanted foreign substances from penetrating the skin.
The condition of epidermis determines how "fresh" your skin looks and also how well your skin absorbs and holds moisture. Wrinkles, however, are formed in lower layers.
The dermis
The dermis is the middle layer of the skin located between the epidermis and subcutaneous tissue. It is the thickest of the skin layers and comprises a tight, sturdy mesh of collagen and elastin fibers. Both collagen and elastin are critically important skin proteins: collagen is responsible for the structural support and elastin for the resilience of the skin. The key type of cells in the dermis is fibroblasts, which synthesize collagen, elastin and other structural molecules. The proper function of fibroblasts is highly important for overall skin health.
The dermis also contains capillaries (tiny blood vessels) and lymph nodes (depots of immune cells). The former are important for oxygenating and nourishing the skin, and the latter -- for protecting it from invading microorganisms.
Finally, the dermis contains sebacious glands, sweat glands, hair follicles as well as a relatively small number of nerve and muscle sells. Sebacious glands, located around hair follicles, are of particular importance for skin health as they produce sebum, an oily protective substance that lubricates and waterproofs the skin and hair. When sebacious gland produce too little sebum, as is common in older people, the skin becomes excessively dry and more prone to wrinkling. Conversely, overproduction or improper composition of sebum, as is common in adolescents, often leads to acne.
The dermis is the layer responsible for the skin's structural integrity, elasticity and resilience. Wrinkles arise and develop in the dermis. Therefore, an anti-wrinkle treatement has a chance to succeed only if it can reach as deep as the dermis. Typical collagen and elastin creams, for example, never reach the dermis because collagen and elastin molecules are too large to penetrate the epidermis. Hence, contrary to what some manufacturers of such creams might imply, these creams have little effect on skin wrinkles.
Subcutaneous tissue
Subcutaneoustissue is the innermost layer of the skin located under the dermis and consisting mainly of fat. The predominant type of cells in the subcutaneous tissue is adipocytes or fat cells. Subcutaneous fat acts as a shock absorber and heat insulator, protecting underlying tissues from cold and mechanical trauma. Interestingly, most mammals lack subcutaneous tissue because their fur serves as a shock absorber and heat insulator. Sweat glands and minute muscles attached to hair follicles originate in subcutaneous tissue.
The loss of subcutaneous tissue, often occurring with age, leads to facial sag and accentuates wrinkles. A common procedure performed by dermatologists to counteract this process is to inject fat (collected elsewhere in the body) under the wrinkles on the face.
The skin consists of three main layers: epidermis, dermis and subcutaneous tissue.
The skin is the largest organ in the body, comprising about 15% of the body weight. The total skin surface of an adult ranges from 12 to 20 square feet. In terms of chemical composition, the skin is about 70% water, 25% protein and 2% lipids. The remainder includes trace minerals, nucleic acids, glycosoaminoglycans, proteoglycans and numerous other chemicals.
The epidermis
The epidermis is the topmost layer of the skin. It is the first barrier between you and the outside world. The epidermis consists of three types of cells keratinocytes, melanocytes and Langerhans cells. Keratinocytes, the cells that make the protein keratin, are the predominant type of cells in the epidermis. The total thickness of the epidermis is usually about 0.5 - 1 mm. At the lowermost portion of the epidermis are immature, rapidly dividing keratinocytes. As they mature, keratinocytes lose water, flatten out and move upward. Eventually, at the end of their life cylce, they reach the uppermost layer of the epidermis called stratum corneum. Stratum corneum consists mainly of dead keratinocytes, hardened proteins (keratin) and lipids, forming a protective crust. Dead cells from stratum corneum continuously slough off and are replaced by new ones coming from below. The skin completely renews itself every 3 - 5 weeks. Most mild peels work by partly removing the stratum corneum and thus speeding up skin renewal.
Another significant group of cell in the epidermis are melanocytes, the cells producing melanin, the pigment responsible for skin tone and color. Finally, Langerhans cells are essentially a forepost of the immune system in the epidermis. They prevent unwanted foreign substances from penetrating the skin.
The condition of epidermis determines how "fresh" your skin looks and also how well your skin absorbs and holds moisture. Wrinkles, however, are formed in lower layers.
The dermis
The dermis is the middle layer of the skin located between the epidermis and subcutaneous tissue. It is the thickest of the skin layers and comprises a tight, sturdy mesh of collagen and elastin fibers. Both collagen and elastin are critically important skin proteins: collagen is responsible for the structural support and elastin for the resilience of the skin. The key type of cells in the dermis is fibroblasts, which synthesize collagen, elastin and other structural molecules. The proper function of fibroblasts is highly important for overall skin health.
The dermis also contains capillaries (tiny blood vessels) and lymph nodes (depots of immune cells). The former are important for oxygenating and nourishing the skin, and the latter -- for protecting it from invading microorganisms.
Finally, the dermis contains sebacious glands, sweat glands, hair follicles as well as a relatively small number of nerve and muscle sells. Sebacious glands, located around hair follicles, are of particular importance for skin health as they produce sebum, an oily protective substance that lubricates and waterproofs the skin and hair. When sebacious gland produce too little sebum, as is common in older people, the skin becomes excessively dry and more prone to wrinkling. Conversely, overproduction or improper composition of sebum, as is common in adolescents, often leads to acne.
The dermis is the layer responsible for the skin's structural integrity, elasticity and resilience. Wrinkles arise and develop in the dermis. Therefore, an anti-wrinkle treatement has a chance to succeed only if it can reach as deep as the dermis. Typical collagen and elastin creams, for example, never reach the dermis because collagen and elastin molecules are too large to penetrate the epidermis. Hence, contrary to what some manufacturers of such creams might imply, these creams have little effect on skin wrinkles.
Subcutaneous tissue
Subcutaneoustissue is the innermost layer of the skin located under the dermis and consisting mainly of fat. The predominant type of cells in the subcutaneous tissue is adipocytes or fat cells. Subcutaneous fat acts as a shock absorber and heat insulator, protecting underlying tissues from cold and mechanical trauma. Interestingly, most mammals lack subcutaneous tissue because their fur serves as a shock absorber and heat insulator. Sweat glands and minute muscles attached to hair follicles originate in subcutaneous tissue.
The loss of subcutaneous tissue, often occurring with age, leads to facial sag and accentuates wrinkles. A common procedure performed by dermatologists to counteract this process is to inject fat (collected elsewhere in the body) under the wrinkles on the face.
Normal Skin
1. Normal skin
This type of skin has a fine, even and smooth surface due to its ideal balance between oil and moisture content and is therefore neither greasy nor dry. People who have normal skin have small, barely-visible pores. Thus, theirskin usually appears clear and does not frequently developspots and blemishes. This type of skin needs minimal andgentle treatment, but does still require maintenance.
This type of skin has a fine, even and smooth surface due to its ideal balance between oil and moisture content and is therefore neither greasy nor dry. People who have normal skin have small, barely-visible pores. Thus, theirskin usually appears clear and does not frequently developspots and blemishes. This type of skin needs minimal andgentle treatment, but does still require maintenance.
Dry Skin
2. Dry skin
Dry skin has a parched appearance and tends to flake easily. It is prone to wrinkles and lines due to its inability to retain moisture, as well as an inadequate production of sebum by sebaceous glands. Dry skin often has problems in cold weather, which dries it out even further. Constant protection in the form of a moisturizer by day and a moisture-rich cream by night is essential. It is important not to over-exfoliate even in cases of extreme flaking, as this only dries out the skin further; gentle exfoliants using sugar, rice bran or mild acids are the most suitable, although they should not be used more frequently than once per week to avoid causing irritation and dryness.
Dry skin has a parched appearance and tends to flake easily. It is prone to wrinkles and lines due to its inability to retain moisture, as well as an inadequate production of sebum by sebaceous glands. Dry skin often has problems in cold weather, which dries it out even further. Constant protection in the form of a moisturizer by day and a moisture-rich cream by night is essential. It is important not to over-exfoliate even in cases of extreme flaking, as this only dries out the skin further; gentle exfoliants using sugar, rice bran or mild acids are the most suitable, although they should not be used more frequently than once per week to avoid causing irritation and dryness.
Oily Skin
3. Oily skin
As its name implies, this type of skin surface is slightly to moderately greasy, which is caused by the over secretion of sebum. The excess oil on the surface of the skin causes dirt and dust from the environment to adhere to it. Oily skin is usually prone to blackheads, whiteheads, spots and pimples. It needs to be cleansed thoroughly every day, especially in hot or humid weather. Moisturizing with an oil-free, water-based and non-comedogenic moisturizer is required in addition. Exfoliation is also necessary, but over-exfoliation can cause irritation and increase in oil production; exfoliants that contain fruit acids are particularly helpful, and fine-grained exfoliants may help to clear blocked pores, discouraging breakouts andimproving the skin's appearance.
As its name implies, this type of skin surface is slightly to moderately greasy, which is caused by the over secretion of sebum. The excess oil on the surface of the skin causes dirt and dust from the environment to adhere to it. Oily skin is usually prone to blackheads, whiteheads, spots and pimples. It needs to be cleansed thoroughly every day, especially in hot or humid weather. Moisturizing with an oil-free, water-based and non-comedogenic moisturizer is required in addition. Exfoliation is also necessary, but over-exfoliation can cause irritation and increase in oil production; exfoliants that contain fruit acids are particularly helpful, and fine-grained exfoliants may help to clear blocked pores, discouraging breakouts andimproving the skin's appearance.