- Rash: Nearly any change in skin's appearance can be called a rash. Most of the rashes are caused by simple skin irritation.
- Dermatitis: A general term for inflammation of the skin. Atopic dermatitis (a type of eczema) is the most common form.
- Eczema: Skin inflammation (dermatitis) causing an itchy rash. Most often, it’s due to an overactive immune system.
- Psoriasis: An autoimmune condition that can cause a variety of skin rashes. Silver, scaly plaques on the skin are the most common form.
- Dandruff: A scaly condition of the scalp may be caused by seborrheic dermatitis, psoriasis, or eczema.
- Acne: The most common skin condition, acne affects over 85% of people at some time in life.
- Cellulitis: Inflammation of the dermis and subcutaneous tissues, usually due to an infection. A red, warm, often painful skin rash generally results.
- Skin Abscess (boil or furuncle): A localized skin infection creates a collection of pus under the skin. Some abscesses must be opened and drained by a doctor in order to be cured.
- Rosacea: A chronic skin condition causing a red rash on the face. Rosacea may look like acne, and is poorly understood.
- Warts: A virus infects the skin and causes the skin to grow excessively, creating a wart. Warts may be treated at home with chemicals, duct tape, or freezing, or removed by a physician.
- Melanoma: The most dangerous type of skin cancer, melanoma results from sun damage and other causes. A skin biopsy can identify melanoma.
- Basal cell carcinoma: The most common type of skin cancer. Basal cell carcinoma is less dangerous than melanoma because it grows and spreads more slowly.
- Seborrheic keratosis: A benign, often itchy growth that appears like a “stuck-on” wart. Seborrheic keratoses may be removed by a physician, if bothersome.
- Actinic keratosis: A crusty or scaly bump that forms on sun-exposed skin. Actinic keratoses can sometimes progress to cancer.
- Squamous cell carcinoma: A common form of skin cancer, squamous cell carcinoma may begin as an ulcer that won’t heal, or an abnormal growth. It usually develops in sun-exposed areas.
- Herpes: The herpes viruses HSV-1 and HSV-2 can cause periodic blisters or skin irritation around the lips or the genitals.
- Hives: Raised, red, itchy patches on the skin that arise suddenly. Hives usually result from an allergic reaction.
- Tinea versicolor: A benign fungal skin infection creates pale areas of low pigmentation on the skin.
- Viral exantham: Many viral infections can cause a red rash affecting large areas of the skin. This is especially common in children.
- Shingles (herpes zoster): Caused by the chickenpox virus, shingles is a painful rash on one side of the body. A new adult vaccine can prevent shingles in most people.
- Scabies: Tiny mites that burrow into the skin cause scabies. An intensely itchy rash in the webs of fingers, wrists, elbows, and buttocks is typical of scabies.
- Ringworm: A fungal skin infection (also called tinea). The characteristic rings it creates are not due to worms.
Sunday, 30 December 2012
Thursday, 27 December 2012
The Epidermis
The epidermis is an outermost layer. It is further subdivided into 5 layers (from deepest to most superficial layer):
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
The Stratum basale (also called Stratum germinativum): This is the deepest layer of the epidermis and it is here that new cells are generated for the renewal of the epidermal layers of the skin. A process of cell division referred to as mitotic division is responsible for the generation of the new epidermal skin cell. After the mitotic division (cell division leading to the formation of a new cell) a newly formed cell will undergo a progressive maturation called keratinisation as it migrates to the surface of the skin.
The Stratum spinosum: The cells that divides in the stratum germinativum soon begin to accumulate to many desmosomes (structures that join adjacent cells together) on their outer surface.
The Stratum granulosum: As keratinocyes (these are the basic cell of which the epidermis is composed) progressively mature they accumulate a protein keratin (this process is called keratinisation). In addition, the cells of the stratum granulosum accumulate dense basophilic keratohylin granules (Granules found in living cells of keratinizing epithelia).
The Stratum lucidum: This is the second layer of the epidermis and varies in thickness throughout the body depending mainly on frictional forces and is thickest on the palms of the hands and soles of the feet.
The Stratum corneum: This layer consists of primarily dead skin cells. As a cell accumulates keratinohylin granules, it is thought that rupture of lysosomal membranes (membrane covering lysosomal enzymes) release lysosomal enzymes (Lysosomal enzymes are those enzymes which are responsible for breaking down complex chemical within a cell which have expended their useful life) that eventually cause cell death. The dead and dying cells filled with mature keratin from the stratum corneum.
The Stratum spinosum: The cells that divides in the stratum germinativum soon begin to accumulate to many desmosomes (structures that join adjacent cells together) on their outer surface.
The Stratum granulosum: As keratinocyes (these are the basic cell of which the epidermis is composed) progressively mature they accumulate a protein keratin (this process is called keratinisation). In addition, the cells of the stratum granulosum accumulate dense basophilic keratohylin granules (Granules found in living cells of keratinizing epithelia).
The Stratum lucidum: This is the second layer of the epidermis and varies in thickness throughout the body depending mainly on frictional forces and is thickest on the palms of the hands and soles of the feet.
The Stratum corneum: This layer consists of primarily dead skin cells. As a cell accumulates keratinohylin granules, it is thought that rupture of lysosomal membranes (membrane covering lysosomal enzymes) release lysosomal enzymes (Lysosomal enzymes are those enzymes which are responsible for breaking down complex chemical within a cell which have expended their useful life) that eventually cause cell death. The dead and dying cells filled with mature keratin from the stratum corneum.
The Dermis
The second layer of the skin, the dermis, consists of various connective tissues. As connective tissue, it contains fibroblasts and macrophages within a gelatinous matrix containing collagen, elastic, and reticular fibres. The structure provides strength, extensibility (the ability to be stretched), and elasticity ( the ability to return to its original form). It is in the dermis where we find capillaries and nerve endings.
It is divided into two layers, the superficial area adjacent to the epidermis called papillary region and a deep thicker area known as the reticular dermis. The dermis is tightly connected to the epidermis through a basement membrane. Structural component of the dermis are
- Collagen
- Elastic fibres and
- Extracellular matrix (previously called ground substance)
- Fibroblasts
- Macrophages
- Adipocytes
Layers of Dermis:
- Stratum papillary
- Stratum reticular
Stratum papillary
The papillary region is composed of loose areolar connective tissue. This is named for its fingerlike projections called papillae, that extend towards the epidermis and contains either terminal network of blood capillaries or tactile Meissner's corpusles.
Stratum reticulare
The reticular region lies under the papillary region and is usually much thicker. It composed of dense irregular connective tissue, and receives its name from the dense concentration of collagenous , elastic, and reticular fibres that weave throughout it. These protein fibres give the dermis its properties of strength, extensibility, and elasticity. Also located within the reticular region are the roots of hair, sebaceous gland, sweat glands, receptor nails and blood vessels.
Stratum reticulare
The reticular region lies under the papillary region and is usually much thicker. It composed of dense irregular connective tissue, and receives its name from the dense concentration of collagenous , elastic, and reticular fibres that weave throughout it. These protein fibres give the dermis its properties of strength, extensibility, and elasticity. Also located within the reticular region are the roots of hair, sebaceous gland, sweat glands, receptor nails and blood vessels.
Thursday, 20 December 2012
Structure of the Human Skin
The skin is the largest organ of the body, with a total area of about 20 square feet. The skin protects us from microbes and the elements, helps regulate body temperature, and permits the sensations of touch, heat, and cold.
The Structure of Human Skin
Skin has three layers:
The Structure of Human Skin
Skin has three layers:
- The Epidermis, the outermost layer of skin, provides a waterproof barrier and creates our skin tone.
- The dermis, beneath the epidermis, contains tough connective tissue, hair follicles, and sweat glands.
- The deeper subcutaneous tissue (hypodermis) is made of fat and connective tissue.
Tuesday, 18 December 2012
Human Skin
The human skin is the outer covering of the body. It is the largest organ of the integumentary system in humans. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs.
For the average adult human, the skin has a surface area of between 1.5-2.0 square metres (16.1-21.5 sq.ft), most of it is between 2-3 mm (0.10 inch) thick. The average sq. inch (6.5 cm. sq.) of skin holds 650 sweat glands, 20 blood vessels, 60,000 melanocytes and more than 1,000 nerve endings.
Skin plays a key role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and protection of vitamin B folates. Severally damaged skin will try to heal by forming scare tissue.
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Human Skin Diagram |
Skin plays a key role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and protection of vitamin B folates. Severally damaged skin will try to heal by forming scare tissue.
Monday, 17 December 2012
SKIN
The skin completely covers the body and is continuous with the membranes lining the body orifices. It:
- protects the underlying structures from injury and invasion by microbes
- contains sensory (somatic) nerve endings of pain, temperature and touch
- is involved in the regulation of body temperature.
SKIN DISEASES
Here I am providing the lots of information about the skin diseases.
