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Skin


About

The skin, which is the uppermost layer of our body, is made up of tissue consisting mainly of three layers: 

  • The epidermis is the outermost layer and forms the primary protective structure called the stratum corneum.
  • The dermis is a fibrous layer that provides strength and support to the upper epidermis.
  • The subcutis is a subcutaneous layer of fat below the dermis that works as a cushion, insulates the body from external forces, and provides nutrients to the other layers.

The purpose of the skin is to protect the body from the external environment and receive sensory stimuli. It covers the internal organs from shocks and wounds and acts as the first layer of defence against germs, viruses, insects etc.

Distinctive Feature

One of the characteristic features of skin is that it continues to change from birth to old age. The skin is very dry, velvety, soft, and free of wrinkles and blemishes in infants and children, while at old age, the skin becomes rough, rugged and full of wrinkles.

Human beings lack body hair which distinguishes them from other land mammals. However, there are certain areas where hair grows copiously.

Those places are referred to as epigamic areas and are concerned with sexual and social communication. These hair follicles are associated with glands that produce body scents.

The body hair becomes thick, long and more pigmented during adolescence, particularly in the pubic region, male face, scalp, and axillae. The physiological and anatomical changes increase as a person ages. The skin not protected by clothes gets exposed to wind, sunlight, and other natural factors that make the skin wrinkled, dry, and flaccid.

The sebaceous glands are present underneath the skin and are responsible for the production of sweat. The human skin shows topographic differences.

For example, you can notice the dissimilarity in the skin between the back of the hands and fingers with the palm.

You can also notice the eyebrows where the skin is coarse, thick and hairy, whereas the eyelid skin is smooth, thin and covered by minute hairs. Multiple layers of tissue provide flexibility and strength to the skin.

Countless sensory receptors enwrap the skin and help the body to communicate with the environment.

The Dermis

The dermis forms the main component of skin and is responsible for physical protection. An association of fibres forms it, and collagen forms the primary material along with glycosaminoglycans. These materials can hold huge amounts of water, which helps maintain the turgidity of the skin.

Extendable elastic fibres help the skin to stretch and return to its normal shape. The skin glands and hair follicles are found in the epidermis. There is a rich supply of blood vessels and contains sense organs and nerves at different levels in the dermis.

Blood & Lymph Vessels

There is an abundant supply of blood vessels in the human skin in veins, arteries and capillaries. This excess supply of blood functions as a cooling system at the disposal of the blood vascular system.

There are sweat glands present too that helps in cooling the body by pouring water over the surface that evaporates, absorbing the body heat.

When the environment is cold, the body conserves warmth, and there is a quick contraction in the cutaneous blood vessel, resulting in a small amount of blood flow.

In contrast, the cutaneous blood vessel contract at long intervals to allow maximum blood flow. The blood flow is full when the body heats up excessively during physical exertion. The skin also regulates blood pressure by controlling the flow of blood through sphincter like vessels.

Underneath the skin is a mesh of lymph vessels. These vessels form a net that runs under the skin and terminates in blind sacs. The lymph vessels lack muscles, and as a result, the lymph circulation is slow and mainly controlled by external forces such as massaging, pressure, skeletal muscle action etc.

The Skin Surface

Hair follicles and sweat glands cover the surface of the skin. The intersecting lines in the skin create furrows that follow a characteristic pattern. The markings are almost similar in every individual, but the details are unique.

The countless number of lines that follow elastic tension form characteristic topography in the body. Such details are unique to every individual, and as a reason, fingerprints are used as personal identification because of clear patterns, high relief and are easy to obtain. Sometimes damages on the skin create marks or lines on the surface.

The Epidermis

The epidermis or the surface of the skin has a varying thickness on different parts of the body. The layer of epidermis at the soles and the palm are thick. The lower layer consists of living cells along with a layer of compact dead cells.

Structure of the Skin

There are many divisions in the skin layer. The uppermost layer of the epidermis is made up of keratin. The purpose of the epidermis is to protect and act as a barrier to the external environment preventing allergens and irritants.

The epidermis layers are stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum basale. The epidermis consists of melanocytes that produce melanin, which saves us by absorbing harmful UV radiation. The size and number of melanocytes determine the colour of the skin.

Following the epidermis is the base membrane, also called the dermo-epidermal junction. This layer joins the epidermis with the dermis. The layer of the dermis is made up of collagen and are an association of fibres.

The dermis layer is much thicker than the epidermis and plays the role of providing support and support to the epidermis. It also helps in cushioning external shocks and protecting the internal organs from injury. The dermis also undertakes to heal.

Beneath the dermis is the hypodermis or the subcutaneous layer, which is composed of fat. It is responsible for structural support as well as maintaining body heat and absorbing shocks. This layer consists of numerous nerves and blood vessels.

Pigmentation

Pigmentation of the skin is the colour of our skin due to the amount of melanin which is a natural pigment present in our skin, eyes and hair and gives it a unique colour. The production of melanin is responsible for the darker or lighter body colour.

The colour also varies for many factors, such as excessive exposure to the sun and acne or related to the genes an individual is born with. The production of melanin is undertaken by a particular type of cells called melanocytes.

The two types of melanin produced are as follows:

  • Eumelanin is black and brown. Its purpose is to block the amount of harmful ultraviolet rays, which otherwise can cause damage to our cells and DNA.
  • Pheomelanin is red and yellow. It provides very little protection from ultraviolet radiation and supports the damage the radiation can cause.

Sweat Glands

The other name of the sweat gland is sudoriparous glands, tiny tubular structures underneath the skin that produce sweat. These type of glands are known as exocrine glands and produce or secrete substances through ducts.

The base of the gland is located in the lower region of the dermis and hypodermis.

Adipose tissues surround the sweat glands. The secretory product is produced by special coils called secretory coils and is controlled by the autonomic nervous system.

The amount of sweat glands is different for every individual and is different for other areas.

There are sweat glands present everywhere in the body except the ear canal, lip, glans penis, clitoris and labia minora.

Now, sweat is nothing but mostly water, along with some electrolytes. It tastes salty because of the presence of sodium chloride. The volume of sweat produced depends on the number of functional glands and the surface area of the opening.

When all the sweat glands work at total capacity, it is estimated that the perspiration rate may exceed three litres per hour.

Skin Types

Skin type varies from person to person, and individuals need to know their type of skin. The different types of skin are as follows:

  • Normal Skin: This type of skin neither too oily nor too dry and follows a regular texture. Generally, this type of skin has no imperfections and visually, it is clean and soft.
  • Dry Skin: This type of skin is caused by weather conditions such as immersing in hot water and less humidity in the air. Though it is a temporary condition, it occurs more often for certain people. It is not a serious disorder but can cause disease like eczema or prone to other skin infections.
  • Sensitive Skin: This type of skin is susceptible and reacts to stimuli, to which there is no reaction in the case of normal skin. This type of skins are fragile and reacts to heat, itching, redness or tightness. It tends to lose the barrier and false prey to different microorganisms. This type of skins require more care and are delicate.
  • Oily Skin: This type of skin is humid, porous and looks bright. Excessive production of fat, particularly by the sebaceous glands, is responsible for such skin. It is usually a genetic or hormone disorder. Young people and adolescents experience such skin types.
  • Scaly Skin: This occurs due to prolonged skin irritation because of environmental factors such as dryness, wind, sun or excessive humidity. These factors result in skin desquamation. It means that the skin detaches from the epidermis like big scales. It can also occur because of an allergic reaction, a fungal infection or cancer. Generally, it is accompanied by itching.
  • Combination Skin: This skin type has the characteristic combination of both oily and dry skin. The distribution of sweat glands and sebaceous glands are not homogenous, and areas more oily are referred to as T-zone (nose, chin and forehead) while the cheeks are dry like normal skin.
  • Skin Moles: These are dark spots on the skin that appear during childhood or adolescence. It occurs due to the grouping of pigmented cells that are generally harmless, but one should contact a dermatologist if there is a change in colour, shape, size, or itching or bleeding.
  • Red Spots: The occurrence of red spots has several dermatological causes and diseases, including infection, allergens, heat, the effect of medications or immune system disorder.

 Skin Conditions

  • Dermatitis: The other name of skin inflammation and the most common form is atopic dermatitis.
  • Rash: Any change in the skin’s appearance is called a rash. It mainly occurs as a result of simple skin irritation.
  • Eczema: It is also a type of skin inflammation along with itchy rash. It occurs mainly due to an overactive immune system.
  • Dandruff: The scalp skin becomes scaly and can occur due to psoriasis, eczema or seborrheic dermatitis.
  • Psoriasis: It occurs with a variety of skin rashes due to an autoimmune condition. Silvery scaly plaques are the most common type of rash.
  • Acne: It is the most ordinary skin condition and affects more than 85% of people at some point in life.
  • Skin Abscess: It is a localized skin infection that creates pus under the skin. It should be opened and cleaned by a doctor to be cured.
  • Cellulitis: It is also a type of inflammation of the middle layer, i.e., dermis and the hypodermis, because of an infection. It occurs as red rashes often accompanied by pain.
  • Warts: Warts are the result of a viral infection that makes the skin grow excessively. It can be treated with duct tape, chemicals, freezing or removed by a doctor.
  • Melanoma: It is the most dangerous type of skin cancer that can occur because of sun damage.
  • Seborrheic keratosis: An itchy growth appears like a wart and should be removed by a doctor.
  • Basal cell carcinoma: It is a common type of skin cancer and is less dangerous than melanoma. It spreads slowly.
  • Actinic keratosis: A scaly bump or a crusty occurs on skin exposed to the sun. Sometimes it can also be the reason for cancer.
  • Squamous cell carcinoma: It is also a common type of cancer that develops like an ulcer.
  • Hives: It is the result of an allergic reaction with itchy, red patches on the skin.
  • Herpes: HSV-1 and HSV-2 are the two herpes viruses and causes blisters or skin irritation at genital areas or lips.
  • Tineaversicolor: It is a type of fungal infection that forms pale areas of low pigmentation.
  • Shingles: It is a type of painful rash caused by the chickenpox virus and can be treated with a new adult vaccine.
  • Viral exanthem: It is a viral infection causing red rashes in the skin.
  • Scabies: It is caused by tiny mites that burrow on the skin causing itchy rash in elbows, fingers and buttocks.
  • Ringworm: It is a type of fungal infection causing rings in the skin.

Skin Tests

  • Skin Testing: In this test, extracts of ordinary substances such as pollens are applied to the skin to observe any allergic reactions.
  • Skin Biopsy: In this type of test, a piece of skin is removed and observed under a microscope to specify skin condition.
  • Tuberculosis skin test: In this test, proteins of the tuberculosis bacteria are injected beneath the skin to check whether the person has tuberculosis.

 Skin Treatments

  • Antibiotics: It is a type of medicine used to kill bacteria that causes cellulitis and other skin infections.
  • Corticosteroids: Some medications reduce the immune system activity, and as a result, these steroids are used.
  • Antiviral drugs: These medicines suppress the activity of the herpes virus.
  • Antifungal drugs: These drugs are used to cure fungal infections.
  • Skin surgery: It is used to remove skin cancers.
  • Antihistamines: It is used to block histamine that causes itching.
  • Immune modulators: These drugs are used to modify immune system activity.
  • Skin moisturizers: These are used to reduce itchiness and irritation caused as a result of dry skin.

 Skin and Nanotechnology

Skin is the biggest organ in the body and is responsible for protecting internal organs, muscles and bones. It acts as the first barrier between the body and pathogens. It helps in regulating temperature and synthesizes vitamin D. So we should take care of our skin.

Nanotechnology is the future of skincare and plays a significant role in protecting the skin. Skincare products are already containing nanoparticles and nanocarriers. Companies are introducing nanotechnology in lotions and creams as a new approach to skincare. It helps in improving sunscreen and delivers molecules through the skin.

Few Interesting Facts about the Skin

  • The skin of a person covers an area of 2 square meters.
  • The skin forms 15% of body weight.
  • There are about 300 million skin cells in an average person.
  • The skin is it’s thickest on the feet and thinnest on eyelids.
  • After every 28 days, the skin renews itself.
  • About 30,000-40,000 dead cells are shed every minute by the skin.

Few Stats and Figures Related to Skin Disease

As per the study, skin diseases are ranked as the fourth most ordinary cause of human illness, and many people do not even consult a doctor. A study was conducted on 2,701 individuals, and it was observed that there were at least one skin abnormality in 1,662 (64.5%) participants.

The most common diseases observed were actinic keratosis (26.6%), rosacea (25.5%), and eczema (11.7%). It was also observed that skin diseases also increase with increasing age, and it is most often in men (72.3%) than women (58.0%). Many participants were even unaware of the abnormal skin findings.