anaphy lec

• Acne


  Caused when blocked skin follicles from a plug caused by oil from glands, bacteria, and dead cells clump together and swell
• Onychocryptosis (Ingrown nail)


  Can affect either the fingers or the toes, nail cuts into one or both sides of the nail bed, resulting in inflammation and infection
• Alopecia areata


  Condition that attacks hair follicles, hair falls out in small, round patches
• Ichthyosis


  Disorder that causes dry, thickened skin, similar to fish scales
• Psoriasis


  Causes red, scaly skin that may feel painful, swollen, or hot
• Integumentary system


  Refers to the integument or the skin, which give rise to a variety of differentiated structures such as hair, nails and glands

  
• Skin and accessory structures


  • Largest organ (15% of body weight), has an area of 1.5 to 2 square meters (22 square feet) in adults, and weighs about 5 kilograms (16% of body weight), thickness varies from 0.5mm thick on the eyelids to 4.0mm thick on the heels of your feet
• Functions of skin


  • Protection (first line of defense, skin being outermost covering of body)
  • Sensory Reception (Free nerve endings are scattered in the dermis of the entire skin, Specialized cutaneous receptors: Pacinian corpuscles, Meissner's corpuscles, Krause end bulbs and Ruffini endings)
  • Maintenance of Body Temperature (Excrete sweat that spreads on the surface of skin to cool body, hair keeps body warm)
  • Non-verbal communication
  • Synthesis of Vitamin D3 (helps regulate the amount of calcium and phosphate in the body)
  • Excretion of salts (carried out by sweat glands in humans, by excreting excess salts and some amount of urea out of body)
  • Acts as excretory organ (Many toxic substances simply evaporate through the surface of skin, Sweat glands serve as excretory organs since they excrete toxins)
• Burns


  Classified depending on how deep and severely they penetrate the skin's surface
• Epidermis


  Contains cells that produce pigment and protect the immune system, histology: keratinized stratified squamous epithelium, avascular (no blood vessels), nourished by diffusion of nutrients from dermis, derived from somatic ectoderm, topmost layer is continuously shed off, gives rise to different structures such as hair, nails, and glands
• Different epidermal cells


  • Keratinocytes (cells that manufacture and store the protein keratin)
  • Melanocytes (cells that produce the skin pigment melanin)
  • Merkel's Cells (detect light touch)
  • Langerhan's Cell (macrophage, guard skin against pathogens)
• Layers of the Epidermis


  • Thin Skin (has all 5 epithelial strata, found in areas subject to pressure or friction, covers all parts of the body, has 4 layers)
  • Thick Skin (more flexible than thin, covers rest of body, provides protection against microorganisms, five layers because of stratum lucidum, found on the palms of hands and soles of the feet)

  
• Callus


  Increase in the number of layers in the stratum corneum, when this occurs over a bony prominence, a corn forms
• Dermis


  Contains nerve endings, oil and sweat glands, and hair follicles, histology: fibrous connective tissue layer, second major layer of the skin, strong, flexible connective tissue, vascular, thickness varies (normally 1-2 mm up to 6 mm)

  
• Composition of Dermis


  • Collagen elastic and reticular fibers
  • Fibroblasts
  • Macrophages
  • Adipocytes
  • Nerves
  • Sweat Glands
  • Hair follicles (also has blood supply)
  • Blood and lymph vessels

  
• Two Dermal Layers


  • Papillary Layer (superficial layer includes dermal papillae, made of loose, areolar connective tissue, contains fibroblasts, small number of fat cells, phagocytes, lymphatic capillaries, nerve fibers, Meissner corpuscles, dermal papillae)
  • Reticular Layer (thicker layer (80%), deeper, composed of dense irregular connective tissue, well vascularized and has rich sensory and sympathetic nerve supply, contains elastin fibers and collagen fibers)

  
• Dermal Papillae


  Finger like projection or fold found in the superficial portion of dermis, increase strength of connection between epidermis and dermis, the greater the folding, the stronger connections are made

  
• Severity of burns


  • First degree (epidermis is damaged)
  • Second degree (epidermis and upper regions of dermis are damaged)
  • Third-degree (the entire thickness of the skin is damaged)

  
• Treatment for burns


  IV nutrition and fluid replacement, debridement, and infection control
• Sense Organs in the Skin


  • Thermoreceptor (senses heat or cold)
  • Meissner's corpuscle (senses touch)
  • Nociceptor (senses pain)
  • Pacinian corpuscle (senses pressure)
• Factors Affecting Skin Color


  • Pigment
  • Blood circulation through the skin
  • Thickness of the stratum corneum
• Abnormal Skin Colors


  • Cyanosis
  • Erythema
  • Jaundice
  • Bronzing
  • Albinism
  • Hematoma
  • Pallor

  
• Skin Derivatives


  • Exocrine Gland (Suderiferous, Sebaceous glands)
  • Nail
  • Hair
• Subcutaneous Tissue


  Made up of fat, connective tissue, and larger blood vessels, histology: hypodermis (adipose tissue for thermoregulation)

  
• Sebaceous (Oil) Glands


  Occur over entire body, except palms and soles, produce oily secretion (sebum) that collects dirt, softens and lubricates hair and skin
• Suderiferous (Sweat) Glands


  Widely distributed on the body, produce sweat (a filtrate of plasma and some waste products), 500ml insensible sweat, diaphoresis (sweating with visible wetness)
• Major types of Sweat Glands

  • Merocrine (eccrine) (involved in thermoregulation, open directly onto the surface of skin - soles of feet and back)
  • Apocrine glands (produce sweat containing fatty acids, confined to axillae, genitalia, around anus, respond to stress and sex involved in scent release)
  • Apoeccrine glands (has a secretory rate as much as 10 times that of the eccrine gland, thought to contribute to axillary hyperhidrosis)
• Ceruminous glands


  Modified merocrine sweat glands located in the external auditory meatus, produce earwax (cerumen) to prevent dirt and insects from entry and keep eardrum supple
• Mammary gland


  Milk-producing gland within the breast and only active during lactation and pregnancy, a modified apocrine sweat gland
• Epidermal Derivatives


  Develop from the epidermis, but are located within the dermis, also called epidermal or skin appendages, e.g. hair follicles

  
• Hair


  An epidermal derivative composed of hard keratin, aka pili or pilus, are characteristics of humans, forms within the epidermal root and becomes keratinized, nourishment comes from blood vessels located within dermal papilla
• Functions of Hair

  • Protection against external factors
  • Producing sebum, apocrine sweat
  • Thermoregulation
  • Acts as sense organs
  • Facilitation of evaporation of perspiration
• Three different types of human hair

  • Lanugo (fine unpigmented hair that covers the entire body of a fetus, shed shortly after birth and replaced with vellus)
  • Vellus (short, downy, "peach fuzz" body hair, unpigmented, grows in most places on the body, occurs on both sexes, make much hair for children, men have smaller percentage around 10%, 2/3 of a female's hair is vellus)
  • Terminal (fully developed hair, longer, coarser, thicker, and darker than vellus hair, found in regions such as axillary, male beard, and pubic)
• Parts of a Hair

  • Hair follicle (tunnel shaped structure in epidermis, determines the shape of the hair)
  • Hair bulb (forms the base of the hair follicle where the living cells divide and grow to build the hair shaft, contains growing hair cells, made up of cuticle, cortex, and medulla)
  • Hair Shaft (part of the hair that can be seen above the scalp, made of protein called keratin)
  • Cuticle (hair's protective layer, composed of overlapping cells, healthy cuticle is smooth and flat, minimizes the movement of moisture in and out of the underlying cortex)
  • Cortex (forms the main bulk and pigment of the hair, health depends on integrity of cuticle)
  • Medulla (present only in thicker hair types, innermost layer of the hair, consists of a soft, thin core of transparent cells and air spaces)
  • Arrector pili muscles (bundles of smooth muscle found at the angle between the hair follicle and the surface of the skin, contract in response to emotion or cold, results in "goose pimples")
• Hair Growth


  Due to mitosis of S.basale cells in epithelial root sheath, scalp hair grows 1 mm every 3 days (10-18 cm/yr)
• Alopecia areata


  Thinning or baldness
• Hirsutism


  Excessive hair growth in areas not normally hairy
• Nails


  Epidermal derivative made up of densely packed cells filled with hard keratin, function is to protect the fingertips and toes, growth rate is 1 mm per week: new cells added by mitosis in the nail matrix

  
• The three major types of skin cancer

  • Squamous Cell Carcinoma
  • Basal Cell Carcinoma
  • Melanoma

  
• Squamous Cell Carcinoma


  Least malignant and most common skin cancer, slow growing and do not often metastasize, can be cured by surgical excision in 9% of the cases, arise most often on scalp, ears, and lower lip