Anatomy of Skin Image

Skin: The Protective Cover of Body

Skin is the largest organ of the body. It is most delicate and with its fleshy coverings, makes people look presentable. While organs like brain, heart and kidney are internal, skin can be seen from outside. Adults carry about 8 pounds (3.6 kg) of skin. Skin serves as a protective layer in our body. Without it, human body would evaporate.

Functions of Skin

Skin performs a wide variety of functions in our daily life. Its primary functions can be broadly summarized as under:

  • Skin is a waterproof, insulating protection which guards our body against extreme temperatures, damaging sunlight and other harmful particles.
  • With its fine shield, skin prevents harmful particles from entering our body.
  • It also radiates anti-bacterial substances, thereby preventing infection.
  • Skin manufactures Vitamin D which converts into healthy bones.
  • Skin is also a huge sensor, packed with sensory nerves that keep brain in contact with the outside world.
  • Finally, skin allows us to move freely due to its high versatility.

Layers of Skin

Skin consist of three different layers-epidermis, dermis and subcutis. The outermost layer is known as epidermis. It mainly consists of cells, known as keratinocytes. Keratinocytes are made of keratin, a tough protein, which is also present in hairs and nails. Several layers are formed in the keratinocytes which constantly grow outwards, as exterior cells deteriorate and die. It takes almost five weeks to form new cells and make their way to the surface. The covering of dead skin is called stratum corneum. It is a horny layer with varied thickness around the body. Dead skin can be more than ten times thicker on the feet soles than around the eyes. Defensive Langerhans cells reside in the epidermis. The main purpose of these cells is to alert the immune system of body against bacteria, viruses and other infectious agents.


The epidermis is what we see. It is connected to a deeper skin layer known as dermis. Collagen fibers and elastin present in the dermis provide strength and elasticity to the skin. The blood vessels help in regulating body temperature by enhancing blood flow to the skin to enable heat to escape,or by restricting blood flow, when it’s cold. Beneath the epidermis, lies a network of nerve fibers and receptors which stimulate feelings of touch, pain and temperature and relays them to the brain.


In the dermis, there are hair follicles and glands along with ducts, which pass throughout the skin. Dermis also houses the sweat glands which helps to bring down the internal temperature through perspiration and simultaneously removes waste fluids like urea and lactate from the body. The apocrine glands, also present in this region, are responsible for producing scented sweat associated with sexual attraction. This also causes body odor, especially around the armpits. Apocrine glands develop during puberty. The sebaceous glands secrete oil-like serum which lubricates hair and skin.


The base layer of the skin is called subcutis. It includes a stratum of fat which serve as a reserve of fuel, during food shortage. An insulating layer, the subcutis cushions us from falls and knocks.

Skin Color

Skin gets its color, from a pigment called melanin. Melanin is produced in the epidermis and protects us from the harmful ultraviolet (UV) rays of the sun, which also has a potential to cause cancer. Dark-skinned people have more number of melanin pigments than fair-skinned. People belonging to tropical regions especially densely forested areas, have darker complexions. In northern latitudes where solar radiation is comparatively weak, fair skin is more common. However, the advantages of dark-skin are completely overshadowed by the strong need for Vitamin D for strengthening bones. Vitamin D is produced on exposure to UV rays.

Regions which are hot, humid and sunny poses serious threat to the skin. Australia has the world’s highest record of skin cancer, with more than 80% of all cancers being diagnosed each year. A majority of Northern European population inhabits Australia.

Collagen: The Most Abundant Protein of Human Body

Skin Comparison and Collagen Image

All about Collagen, Facts, Medical Uses & Potential Threats to Collagen

What is Collagen?

Collagen is a protein substance in body that holds the entire body together. It is a hard, insoluble and fibrous protein which constitutes about one-third of protein content in body. In major collagen structures, the molecules are packed together and form similar long, thin fibrils. According to MediLexicon, collagen is a family of genetically distinct molecules, having a unique triple helix configuration of three polypeptide subunits, called alpha-chains. Each of these chains contains about 1,000 amino acids and features a common amino acid sequence, comprising of glycine, proline and hydroxiproline.

Collagen is mostly found in muscles, bones, skin and tendons where it provides strength, stability and firmness by a scaffold formation. These collagens are strong and flexible. Collagen that is synthesized by the body plays significant roles in maintaining good health and physical structure. When natural collagen formed in the body depletes or breaks down, it poses serious health issues and critical problems. Exogenous or supplemental collagen is mainly used for medical and cosmetic reasons, including repairing and healing body’s tissues.

Facts about Collagen

Some important facts about collagen are stated under:

  • The word “collagen” has been derived from the Greek word “kolla” meaning glue.
  • Apart from skin and bones, collagens are also found in connective tissues.
  • There are almost 16 different kinds of collagen found in body, of which, 80-90% belong to types I, II and III.
  • Type I collagen fibrils have tensile strength and are even stronger than steel and gram.
  • Protein consist about 20% of body mass and 30% of this protein consist of collagen.
  • Apart from giving strength and structure to skin, collagen also replaces dead skin cells.
  • As human progress in age, collagen production decreases, as part of intrinsic ageing. Collagen is also reduced by ultraviolet light exposure and various other environmental factors. This is known as extrinsic ageing.
  • In medical products, collagen can be derived from porcine, bovine, human and ovine sources.
  • Collagen dressings attract new skin cells to the wounded regions.
  • Cosmetic products especially revitalizing lotions which claim to increase collagen levels are most unlikely to do so, since the collagen molecules are large enough to be absorbed through the skin.
  • Laser therapy and all-trans retinoic acid (a source of Vitamin C) can influence collagen production.
  • Smoking, sunlight and high sugar consumption are some of the controllable factors which cause damage to collagen production.

Collagen and Body

Collagen is mostly found in skin, bones, tendons and connective tissues and the main purpose is to provide strength, support and elasticity to the skin. Collagens are also found in the extracellular matrix which is an intricate network of macromolecules that assess the physical properties of tissues in body.

In dermis (middle layer of the skin), collagen helps to form a fibrous network, on which new cells grow. Collagen is also essential for replacing and restoring dead skin cells. Some collagens also serve as proactive coverings for delicate organs in human body, like kidneys.

As collagen production decrease with age, the structural integrity of skin gradually reduces which leads to sagging and drooping skin. Skin becomes loose, fine lines, wrinkles and age-related lines appear on the skin and the cartilage in joints weakens.

Although variety of different cells secretes collagen, the connective tissue cells primarily secrete collagen. At young age, collagen is consistently produced by body, however, from the age of 40 collagen synthesis starts to decline. In women, there is drastic reduction in collagen synthesis after menopause. By the time one attains 60, there is considerable decline in collagen synthesis and production.

Medical Uses & Potential Threats to Collagen

How is collagen medically useful?

Collagen can be broken down and incorporated by the body. It is resorbable, functionally diverse and occurs naturally. Therefore, collagen has various medical uses and is used for various medical devices. Besides this, collagens can also be made clinically versatile by forming into compacted solids or lattice-like gels, which being prepared for use. Collagens that are medically used originate from sources like porcine, bovine, human and ovine and are used in the following medical applications:

Wound Dressing

Collagen helps in improving healing, attracting new skin cells to the wounded site and facilitates growth of new tissue. There are certain types of wounds like chronic non-healing wounds, granulating or necrotic wounds, exuding wounds, second-degree burns, partial and full-thickness wounds, skin grafts and skin donation sites which are aided by using collagen dressings. Collagen dressings are however not suitable for third-degree burns, wounds that are covered in dry eschar or for patients who are sensitive to bovine products.

Skin Fillers

The collagen fillers originate from human and bovine sources. Collagen serves as excellent skin fillers when they are injected into specific areas on skin to improve skin contours and fill out vacuums. It can fill moderately superficial defects. Collagens are also equally useful when cosmetically used for removing various age-related lines, wrinkles, scar marks, acne and other similar signs from face. People infected with severe allergies must go for skin tests prior to injecting bovine collagen, since it can pose further complicacies and bring more health issues.

Vascular Prosthetics

Collagen tissue grafts from donors are used in peripheral nerve regeneration, vascular prostheses and arterial reconstruction. There are some prostheses which are thrombogenic, which means they cause coagulation of blood. However, at the same time, these prostheses are easily compatible with the host body.

Guided Tissue Regeneration

Membranes which are based on collagen are commonly used in periodontal and implant theory. This helps in promoting growth of particular types of cells. In oral surgeries, barriers can be used for preventing fast growth of cells of gingival epithelium, which migrates to a wound in the tooth. As a result, there can be preserved space which will enable tooth cells to potentially regenerate. Apart from healing features, the primary advantage of using collagen-based membrane is that the body can break down the collagen and assimilate protein, with time. Therefore, it is reabsorbable. Hence, patients don’t require further surgeries to remove their barriers.

Skin Revitalization

Although many products like creams and lotions claim to contain collagen to rejuvenate skin; however, this is practically impossible since the collagen molecules are too big to be absorbed through the skin. These products, which might contain collagen, only moisturize and nourish the skin, without directly increasing collagen concentration.

Osteoarthritis Treatment

Collagen formulations fetch productive results in osteoarthritis. In quite a number of experiments, collagen has been proven to reduce pain. Studies suggest that collagen hydrolysate gradually decreases painful symptoms of osteoarthritis and improves function of joints. In some cases, it was also found that the collagen supplement was well absorbed and collagen was accumulated in cartilage. As a result, specialized joint cells, called chondrocytes were stimulated to create extracellular matrix.

How to increase collagen production?

  • Laser therapy in combination with intense wavelengths of light stimulates growth of elastin, melanin and collagen. This technique is also useful for treating stretch marks.
  • Collagen being a protein is made of amino acids. The nine most essential amino acids cannot be produced by body itself, it has to be acquired through right diet and nutrients such as
    • Proline: Meat, cheese, egg-whites, cabbage and soy.
    • Anthocyanidins: Blueberries, raspberries, cherries and blackberries.
    • Copper: Nuts, shellfish, red-meat and some drinking water.
    • Vitamin A: Food derived from animals and plants like beta-carotene
    • Vitamin C: Strawberries, broccoli, oranges and pepper.

What damages collagen?

Collagen levels deplete with time and age and there is no prevention to intrinsic aging. However, there are quite a number of external factors which contribute to collagen depletion. If such factors can be controlled; smooth, tight and healthy skin can be maintained for a longer period of time. Simultaneously, collagen can be protected and bones, muscles and joints can be kept healthier. In this context, the common collagen depleting factors are:


Tobacco smoke contains harmful chemicals and many of these cause damage to both collagen and elastin in skin. Nicotine, present in high proportion in tobacco, narrows the blood vessels in the outer skin layers which ultimately reduces nutrient and oxygen supply to the skin. This compromises health and brings aging signs earlier. Collagens are also affected, which is why, skin loses its strength and gradually droops.


Sunlight contains ultraviolet rays, which breaks down collagen, at a rapid rate. Collagen fibers get damaged and abnormal elastin gets accumulated in the skin. Excess abnormal elastin buildup produces a harmful enzyme, which further breaks down collagen. As a result for multiple collagen breakdowns, skin can develop solar scars.

High sugar consumption

Consuming diet that is rich in sugar enhances glycation rate, following which, sugar contained in the blood attaches to protein to develop new molecules known as advanced glycation end products (AGEs). The AGEs cause serious damage to adjacent proteins and makes collagen dry, feeble and fragile.

Autoimmune disorders

Owing to certain autoimmune disorders, antibodies target collagen. Gene mutations that are responsible for coding of alpha-chains of collagens affect the extracellular matrix. This leads to a decreased amount of collagen secretion or dysfunctional secretion of mutant collagen.