Our skin is considered to be the largest organ that covers the entire body. It consists of about 7 percent of the total body weight. Composed of 3 unique layers - Epidermis, Dermis and Hypodermis, the skin serves a number of important functions.

Skin is the first layer of contact and defense for your body that allows you to perceive your surroundings through the sense of touch and protects you from pathogenic attacks.

The pilosebaceous unit comprising sweat glands, hair follicles, sebaceous gland and arrector pili muscle also forms a part of your skin.

Ayurveda recommends the study of ‘twacha shareer’ or anatomy of the 7 layers of skin for better understanding of your Prakriti (body constitution) and effect of different Doshas on your skin health. 

MODERN REVIEW

The skin is the first line of defense against the envioronmental agent and mirror or internal pathology.

Embryological Description:

The skin is developed from the surface ectoderm and its underlying mesenchyme (Mesodermal cells).

 1) Surface ectoderm gives rise to the kertinizing general surface epidermis and its appendages, the    pilosebaceous units, sudariferous glands and nail units at about 8:10 weeks of gestation.

2) Malacocites, nerves and specialized sensory receptors arise from the neuroectoderm.

3) Dermis and its other elements in the skin that is langerhans cells, macrophages, mass cell, fibroblasts etc originate from the mesoderm.

Macroscopic structures:

The skin is the organ of integumentory system that is covering system of the body. It is formed by about:

       8% of the total body mass.

       2.2 square meter covering area.

       16% of total body weight.

Thickness of the skin is different according to maturation, aging and regional specialization. It may be 0.5 mm on the eyelidand 4 mm on heal. Most of the body skin is average 1:2cm thick. Skin is a fascinating orgain as it forms a self renewing and self repairing interface between the body and its environment. Within limit, it forms an effective barrier against microbial invasion and has properties which can protect against mechanical, chemical, cosmetic, thermal and phototic damage.

Microscopic Structure:

It is characterized by the epidermis, dermis and adenaxa.

1) Epidermis: It is a compound tissue consisting mainly of the continuously self replacing keratinized stratified squamous epithelium. It varies in thickness 0.04 mm on the eyelid and 0.16 mm on palms, 0.1 mm is average thickness. Epidermis contains five layers (Strata).

1) Stratum bascal

2) Stratum spinosum

3) Stratum granulosum

4) Stratum corneum

5) Stratum lucidum

1) Stratum Bascal: It is deepest layer of the epidermis and formed by a single row of columnar kerationcytes. Four types of cells are germinated through these layers which are keratinocytes, melanocytes, langerhans cells and merkels cells.

2) Stratum spinosum: It lies super ficial to bascal and it consists of 5 to 12 layers of polyhedral keratinocytes cells are joined tightly to other cells by bundles of intermediate filaments of the cytoskeleton.This arrangement provides both strength and flexibility.

3) Stratum granulosum: It is 3 to 5 layers of flattened kerationocytes that contains darkly staining granules of proteins called karatophylin. The lipid rich secretion produced by the lamellar granules work as a water repellent sealant that retards loss of body fluid and entry of foreign materials.

4) Stratum lucidum: It is present only in the skin of fingertips, palms and soles. It consists of 3:5 layers of clear, flat, dead kerationocytes.

5) Stratum corneum: This is the most superficial layer consisting of anucleated flattened confirmed 25:30 layers of dead karatinocytes. These cells are continuously shed and replaced by cells from the deeper strata. It serves as an effective water repellant barrier and also protects against injury and microbes.

Adnexa of epidermis: It contains the eccrine glands, apocrine glands and the pilosebaceous apparatus.

1) Eccrine glands: These are distributed all over body except the venillion borders of the lips nailbeds, labia minora, glans penis etc.There density is maximum on the palms, sales and axillae.These glands initiate the sweat formation which dissipate heat by evaporation.

2) Apocrine glands: These are located in the axillar, areolae, periumbilical, perianal, external ear etc areas. These are small and nonfunctional till puberty, after which they enlarge.

3) Hair follicles: They presents all over body except sime parts like palm, sole etc and they protects scalp from injury and sunrays and decrease heat loss.

4) Sebaceous gland: They are lipid producing structures disturbed all over body except palms and soles.

5) Nail unit: The nail unit helps in the appreciation of the fine and tactile stimulation, protect the terminal phalanges from trauma.

Dermis: The dermis rests upon the subcutaneous fat and is 15:40 time thicker than the epidermis. The dermis is composed mainly of noncellular connective tissue containing collagen, elastic tissue and ground substances within which are embedded the nerves, blood vessels, lymphatics, muscles, and pilosebaceous apocrine and eccrine sweat unit. Dermis can be divided into

1) Superficial: Papillary region: It consists of areolar connective tissue containing fine elastic fibers. Elastic fibers play a role in maintaining the elasticity of the skin.

2) Deeper: Reticular region: It consists of dense irregular connective tissue containing bundle of collagen and some elastic fibers. Both these provides strength elasticity to skin.

Pigmentation of Skin: Melanin, carotene and haemoglobin: these three pigmemts give skin a wide variety of colour. Melanin located in epidermis, carotene is mostly in the stratum corneum and dermis and haemoglobin is in red blood cells within capillaries in the dermis.

Physiology of Skin:

1.     Thermoregulation

2.     Protection

3.     Cutaneous Sensation

4.     Excretion and absorption

5.     Synthesis of vitaminD

6.     Immunity

7.     Blood reservoir

8.     Socio sexual communication

9.     Individual identification

Functions Of Different Layers Of Skin

From the ‘Kriyatamaka’ or functionary aspect, the different layers of your skin are invested with unique support systems that help it to carry out its various functions.

According to the ancient science of Ayurveda, the three Doshas or bodily humours play an important role in the smooth running of skin functions. An imbalance of the Vata, Pitta and Kapha Doshas can directly interfere with skin functions resulting in the accumulation of harmful Ama toxins in your skin and a vitiation of the Rakta Dhatu (blood tissue). This can lead to various skin issues like dryness, acne, eczema, infection, hyperpigmentation, discolouration and premature skin ageing.

A. Functions Of The Epidermis

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1. Skin Barrier

The epidermis acts like a protective barrier against pathogens and mechanical and thermal stress. It also protects the underlying tissues, muscles and organs from external damages. Sebum, sweat and secretions from your natural microbiome (good bacteria that lives on your skin) make up the acid mantle, a protective layer that prevents the growth and invasion of harmful microbes. Moreover, Langerhans cells present in the epidermis immediately signal your immune system in case of infection or injury to the body.

2. Retains Moisture

Moisture retention is an important function of the epidermal layer. The cells in the stratum corneum are bound together in a lipid matrix that prevent water loss from the surface of your skin. This is crucial for maintaining healthy skin. Skin that has a depleted lipid matrix often faces issues such as dryness, eczema, wrinkles and premature skin ageing.

3. Produces Melanin

The epidermis protects your body from the harmful UV rays of the sun that can cause cell damage and skin cancer. Whenever your skin is over exposed to the sun, melanin synthesized in the stratum basalis is transferred to the stratum corneum by melanosomes to deflect and absorb UV radiation (UVA and UVB rays). This is why you happen to tan under the sun.

The pigment melanin also gives you your skin colour. According to Ayurveda, the ‘Bhrajaka Pitta Dosha’ that is seated in the skin helps regulate melanin production. However, an aggravation of the Bhrajaka Pitta can cause overproduction of melanin, resulting in hyperpigmentation. This can lead to skin problems like age spots and melasma.

4. Sensation

Merkel cells present in the basale layer of the epidermis lie close to the nerve endings in the dermal layer. These assist in perceiving the sensations of touch, temperature, pressure and pain.

5. Synthesis Of Vitamin D

Vitamin D is critical for maintaining skin health and running its various functions. From strengthening the epidermal barrier, fostering hair growth to cell renewal, Vitamin D plays a key role. One of the main functions of the epidermis is the synthesis of Vitamin D. Keratinocytes in the epidermis have special enzymes that can convert 7-dehydrocholesterol into Vitamin D when exposed to the sun.

B. Functions Of The Dermis

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1. Nourishment

The dermis is a highly vascular skin layer, meaning it has lots of blood vessels that bring nutrition to the upper epidermal layers. Moreover, sebum produced by sebaceous glands present in the dermis nourish and moisturize your skin. This prevents dry skin and premature skin ageing.

2. Thermoregulation

Being part of the integumentary system, the dermal layer of skin plays an important role in regulating body temperature. Optimum body temperature is required for the smooth generation and function of body enzymes. When there is a rise in body temperature, the hypothalamus signals your sweat glands present in the dermis to release sweat.

Through the evaporation of sweat from the epidermal surface, your body releases excess heat. Body heat is also reduced by increasing the subcutaneous blood flow. Blood vessels in the dermis dilate to bring excess blood to the skin. This allows for heat to escape from the surface of your skin.

When there is a drop in temperatures, the blood vessels constrict and sweat production is controlled to trap heat inside your body.

3. Sensation

Sensory receptors present in the dermal layer of your skin allow for perceptions of touch. Due to their presence you can feel the temperature, pressure and texture of the objects that you touch. There are around 3 main types of tactile receptors, each equipped for different sensations or stimuli.

Mechanoreceptors are for sensing mechanical forces such as stretches, pressure, texture, vibrations on the skin. Thermoreceptors sense temperature changes around you. Reflex actions when you touch something hot or cold are controlled by your brain depending on the signals sent by these receptors. Nociceptors sense pain.

4. Excretion And Absorption

Your skin also eliminates body wastes through the sweat produced by sweat glands present in the dermis. Excess water, urea, salts (mainly sodium and chloride) are excreted through sweat to maintain their optimum levels in your blood.

The skin acts as a semi-permeable layer that allows certain fat soluble vitamins to enter and nourish the skin. It also allows for topical drug absorption to fight skin issues and infections.

5. Immunity Against Infections

The dermis hosts a vast number of immune cells such as lymphatic vessels, dendritic cells, killer cells and others. In case of an injury that results in the damage of the epidermal barrier, these immune cells help fight off opportunistic pathogens and prevent chances of infection.

C. Functions Of The Hypodermis

1. Energy Reserve

The hypodermis is the deepest layer of your skin that stores fat which aids in thermoregulation. It also acts as an energy store house for the body.

2. Cushioning

Being a layer of fatty tissues, the hypodermis provides added protection from injuries. It absorbs shocks and pressures and prevents damage to the muscles and organs underneath it. It also provides structure and support to the upper layers of the skin.

AYURVEDIC REVIEW

Ayurved is not only an ancient Indian Medical science but it is a science which gives knowledge about life. Maintaining health of a healthy person & curing a disease are twofold aims of Ayurved.

3 Dosha i.e. Vata, Pitta, Kapha; 7 Dhatu i.e. Rasa, Rakta, Mansa, Meda, Asthi, Majja & Shukra; 3 Mala i.e. Mutra, Purisha & Sweda are the basic elements of human body. Balance state of 3 Dosha, 7 Dhatu & 3 Mala is essential to maintain health of healthy person while imbalance in any of these elements lead to various diseases. Different diseases manifest according to various causative factors, aggravation of Dosha causing vitiation of Dhatu & Mala; constitution of a person, season, habitate etc.

Skin diseases called as “Kustha” in Ayurvedic texts are caused due to vitiation 7 body elements i.e. 3 Dosha viz Vata, Pitta, Kapha & 4 Dushya viz skin (twak), Rakta, Mansa & ambu (water element).

SKIN LAYERS ACCORDING TO AYURVEDA:

1.  Avabhasini:

As the outermost layer, it is the source of complexion and reflects the quality of the Rasa Dhatu (primary nutrient fluids) in our body.  This indicates any inner health or disorder that we may have and whether the body’s physiology as a whole is balanced or imbalanced.  Devoid of its own colour, it reflects the colours of inner layers and the aura of the individual.  When affected, pimples, acne, dandruff etc arise on the body.  It resembles the colour of molton iron.

2.  Lohita:

As the second layer, Lohita supports the outermost layer and indicates the quality of Rakhta Dhatu (blood).  Any changes or impurities on this layer affects the Avabhasini layer and can cause moles, dark circles or black pigmentation of the skin when impure.

3.  Shweta:

As the third layer, it is white and provides balance to skin colour, lightening the darker colours of the inner layers.  When impaired by doshas, it can cause diseases like eczema, allergic rashes etc.

4.  Tamra:

As the fourth layer, Tamra nurtures the upper layers of the skin and supports the immune system.  It helps the skin perform its function of being a barrier.  Copper coloured, dosha of this layer causes skin infections.

5.  Vedini:

All sensations and feelings lie in this fifth layer which connects the skin to the rest of the body.  Dosha of this layer can cause diseases like herpes.

6.  Rohini:

This layer supports healing and regeneration.  Imbalance in this layer retards healing and the disappearance of scars over time and can cause cancer, tumors etc.

7.  Mamsadhara:

As the innermost layer of the skin, Mamsadhara is the platform for the skin’s stability and firmness.  When affected by doshas, it can cause abscesses or fistulas.

Different causative factors of skin diseases

A) Dietary causes –

1) Excessive intake of liquid food

2) Excessive intake of unctuous / oily food i.e. deep fried things like Pakora

3) Excessive intake of heavy food i.e. Cheese, Paneer

4) Excessive intake of yoghurt

5) Excessive intake of fish

6) Excessive intake of black gram

7) Excessive intake of raddish

8) Excessive intake of sesame

9) Excessive intake of milk & milk products

10)Excessive intake of jaggery

11)Excessive intake of recipes prepared from dove e.g. Paratha, bread

12)Excessive intake of sour food like vinegar, sauce

13)Excessive intake of salty food like pickle, ruffles

14)Overeating

15)Newly ripped grains

16)Incompatible diet like fish & milk together, sour fruits & milk together

17)Fermented food like bread, Dosa

B) Behavioral causes –

1) Exercise immediately after taking meal

2) To become angry after taking meal

3) Cold water intake / bath immediately after physical exercise

C) Vegavarodha (Withholding natural urges) –

Withholding all natural urges specially urge of vomiting can cause various skin diseases.

These causative factors vitiate 3 Dosha & 4 Dushya i.e. Skin, Rakta, Mansa & Watery element in the body, which are responsible for manifestation of skin diseases.

D) Specific causes –

Ayurved believes that some diseases like skin diseases, fever are also caused due to misbehavior done in previous birth like disobeying teachers, spiritual masters.

Types of skin diseases

According to Ayurved skin diseases are divided into mainly 2 types which are again subdivided into 7 & 11 types.

1) Mahakustha (Major skin diseases) – 7 in numbers

2) Kshudrakustha (Minor skin diseases) - 11 in numbers

All these 11 types of Kustha can be classified & treated as per dominance of Dosha.

· Vata dominance skin diseases in which affected skin becomes dry, rough, having black / gray discolouration & pin pricking pain.

· In Pitta dominant skin diseases patient suffers from local burning sensation, red discolouration, foul smell, pustular discharge.

· White discolouration, itching, coldness, infected wound are the symptoms of Kapha dominant skin diseases.

· Dominance of 2 or all 3 Dosha exhibit the symptoms of respective 2 or 3 Doshas.

Do's –

Common principles of diet – Diet having Pungent, Bitter & Astringent taste; & the diet which is light to digest is recommended.

1) Cow’s milk – 200 ml + Turmeric powder – 1 pinch

2) Buttermilk – 200 ml + cumin seed powder – ¼ teaspoon

3) Boiled hot water for drinking

4) Grains – Roasted rice, Barley

5) Beans – Green gram, Red lentil

6) Vegetables- Fenugreek leaves, Bitter gourd, White pumpkin, Snake gourd

7) Condiments – Cumin seeds, Turmeric, Coriander seeds & leaves, Garlic, Mint leaves, Curry leaves, Black pepper.

8) Recipes – Green gram Khichadi, Paratha of fenugreek leaves, Chutany of Garlic, Mint & coriander

Don’ts –

Common principle – Diet having Sweet, Sour & Salty taste & the diet which is heavy to digest should be avoided.

1) Chilled water, cold drinks

2) Buffalo milk, Yogurt, Cheese, Paneer

3) Jaggery

4) Excessive salt, salty food like ruffles

5) Excessive sour things like Vinegar, Sauce

6) Excessive sweet things like chocolate, various milk products

7) Black gram, Kidney bean, Horse gram

8) Chilli, Capsicum

9) Cucumber, Tomato

10) Banana, sour fruits, fruit salad