Chapter 10: Skin Deep
Test me: Integumentary system Pages 250-251
Diagnostic procedures performed on the integumentary system include the following: - biopsy = removal of living tissue for examination of life (bi/o, -opsy, incisional biopsy, incision, excisional biopsy, excision) - culture = diagnostic or research procedure used to allow microbes to reproduce in predetermined media (tissue culture ) - exfoliative cytology = scraping of cells from tissue and examination under a microscope (exfoliative) - Intradermal skin testing = injection of test substances into the skin layer to observe a reaction (atopy, purified protein derivative) - Skin scrape = microscopic examination of skin for the presence of mites
Procedures: Integumentary system Page 259
Procedures performed on the integumentary system include: - cauterization = destruction of tissue using electric current, heat or chemicals - cryosurgery = destruction of tissue using extreme cold - debridement = removal of tissue and foreign material to aid healing - lance = to open or pierce with a lancet to allow drainage - laser = device that transfers light into tan intense beam for various purposes
Hair Page 247
- Hair is rodlike fibers made of dead protein cells filled with keratin - pil/i, pil/o, trich/o = hair - The hair shaft is the portion of hair extending beyond the skin surface and is composed of the cuticle, cortex and medulla - The cuticle is one cell layer thick and appears scaly - The cortex is the main component of the hair shaft, is several layers thick and is responsible for coat color - The medulla is the innermost component of the hair shaft - The root is the portion of the hair below the skin surface and is surrounded by a hair follicle - Hair follicles are tubes that hold the hair fibers - The arrector pili is a tiny muscle attached to the hair follicle that causes the hair to stand erect in response to cold temperatures or stress - Piloerection is the condition of the hair standing straight up
Nails, claws and hooves Pages 247-249
- Nails, claws and hooves all have a wall, sole and pad, although they may be called different things - Walls usually are located dorsal an lateral to the distal phalanx - The sole is located ventral to the distal phalanx and usually is flaky - Foot pads, or tori, provide cushioning and protection for the bones of the foot - Dogs and cats have digital pads on the palmar and plantar surfaces of the phalanges - Metacarpal and metatarsal pads are singular pads located on the palmar and plantar surfaces of the metacarpal and metatarsal areas - Carpal pads are located on the palmar surface of each carpus - Digitigrade - Plantigrade - The suffix -grade means to go - In dogs and cats, nails and claws are keratin plates covering the dorsal surface of the distal phalanx - Quick - Quicking - The combining form for claw is onych/o - Hooves are the horny covering of the distal phalanx in ungulates, or hooved animals, such as equine, ruminants and swine - The combining form for hoof is ungul/o - The corium is the dermis of the hoof and is located under the epidermal surface of the hoof wall, sole and frog What is hair (chart on page 248) - fur - pelt - guard hairs (primary hairs or topcoat) - secondary hairs - tactile hair (vibrissae) - cilia - simple pattern hair growth - compound pattern hair growth - shedding The equine hoof is divided into various regions (chart on page 249) - coronary band (coronet) - periople - wall - bars - sole - frog - bulbs of heel
Skin Page 244
- Skin covers the external surfaces of the body - The skin is composed of epithelial tissue and is sometimes called the epithelium - The combining forms for skin are cutane/o, derm/o and dermat/o - The suffix -derma means skin - Dermatology is the study of skin
Functions of the integumentary system Page 243
- The integumentary system consists of skin and its appendages (appendages include glands, hair, fur, wool, feathers, scales, claws, beaks, horns, hooves and nails) - Skin is a physical barrier that protects animals from microbial infection, injury, ultraviolet rays, chemicals and toxins - Skin also plays a role in waterproofing the body, preventing fluid loss, providing temperature regulation through vasodilation and vasoconstriction, excreting wastes, providing species-specific coloration, sensation and providing a site for vitamin D synthesis - Exocrine glands, both sebaceous and sweat, are located in the integumentary system - Sebaceous glands lubricate the skin and discourage bacterial growth on the skin - Sweat glands regulate body temperature and excrete wastes through sweat - Hair helps control body heat loss and is a sense receptor - Nails protect the dorsal surface of the distal phalanx
Structures of the integumentary system Page 244
- The integumentary system is on the outside of the body and is resilient and versatile because it is subjected to a variety of insults such as trauma, toxic chemicals and environmental conditions
Skin association Page 246
Appendages or structures associated with the skin include glands, hair, fur, wool, feathers, scales, claws, beaks, horns, hooves and nails
Pathology: Integumentary sytem Pages 252-259
Pathological conditions of the integumentary system include: - abrasion = injury in which superficial layers of skin are scraped - abscess = localized collection of pus (caseous) - acne = skin inflammation caused by plugged sebaceous glands and comedone development from papules and pustules (chin acne) - acute moist dermatitis = bacterial skin disease that is worsened by licking and scratching (hot spot) - alopecia = hair loss resulting in hairless patches or complete lack of hair (alopec/o, shedding) - atopy = hypersensitivity reaction in animals involving pruritus with secondary dermatitis (allergies, allergic dermatitis, hypersensitization, hyposensitization) - bullae - multiple contained skin elevations filled with fluid that are greater than 0.5 cm in diameter (bulla) - burn = tissue injury caused by heat, flame, electricity, chemicals or radiation - carbuncle = cluster of furuncles - carcinoma = malignant neoplasm of epithelial tissue (carcin/o) - cellulitis = inflammation of connective tissue (diffuse, localized) - comedo = blackhead or buildup of sebum and keratin in a pore (comedones) - contusion = injury that does not break the skin - crust = collection of dried sebum and cellular debris - cyst = closed sac or pouch containing fluid or semisolid material - dermatitis = inflammation of the skin (contact dermatitis) - dermatocellulitis = inflammation of the skin and connective tissue - dermatomycosis = abnormal skin condition caused by superficial fungus (dermatophytosis, dermatophytes) - dermatosis = abnormal skin condition (dermatoses) - discoid lupus erythematosus = canine autoimmune disease in which the bridge of the nose exhibit depigmentation, erythema, scaling and erosions - dyskeratosis = abnormal alteration in keratinization - ecchymosis = purplish nonelevated path of bleeding into the skin (bruise, ecchymoses) - ecthyma = skin infection with shallow eruptions caused by a pox virus (soremouth) - eczema = general term for inflammatory skin disease characterized by erytheme, papules, vesicles, crusts and scabs either alone or in combination - eosinohilic granuloma complex = collective name for autoimmune lesion of eosinophilic ulcer, eosinophilic plaque and linear granuloma found in cats and rarely in dogs (eosinophilic ulcer, rodent ulcer, eosinophilic plaques, linear granulomas) - erythema = skin redness (erythematous) - erythroderma = abnormal redness of skin occurring over a widespread area (erythr/o, erythem/o, erythemat/o) - exanthema = cutaneous rash caused by fever or disease (exanthem) - excoriation = skin surface injury caused by self-trauma - feline miliary dermatitis = skin disease of cats in which multiple crusts and bumps are present predominantly on the dorsum - fissure = cracklike sore - fistula = abnormal passage from an internal organ to the body surface or between two internal organs (fistulae, fistul/o) - flea allergy dermatitis = inflammation of the skin caused by an allergic reaction to flea saliva (allergen) - footrot = bacterial hoof disease that spreads from the interdigital skin to the deeper foot structures - frostbite = tissue damage caused by extreme cold or contact with chemicals with extreme temperature - furuncle = localized skin infection in a gland or hair follicle (boil, furunculosis) - gangrene = necrosis associated with loss of circulation (necrosis, necrotic, putrefaction) - granuloma = small area of healing tissue - hemangioma = benign tumor composed of newly formed blood vessels - hyperkeratosis = abnormal condition of increase growth of the horny layer of the skin (acanthokeratodermia) - infestations = occupation and dwelling of a parasite on the external surface of tissue (ectoparasites, ecto-, louse, lice, pediulosis, mite, mange, sarcoptic, demodectic, chiggers, acariasis, maggots, myiasis) - keratosis = abnormal condition of epidermal overgrowth and thickening (keratoses) - laceration = accidental cut into the skin - lesion = pathologic change of tissue - lipoma = benign growth of fat cells (fatty tumor) - macule = flat, discolored lesion less than 1 cm in diameter (macula) - melanoma = tumor or growth of pigmented skin cells (malignant melanoma, amelanotic melanoma) - nodule = small knot protruding above the skin - onychomycosis = superficial fungal infection of the claw - pallor = skin paleness - papilloma = benign epithelial growth that is lobed (papill/o or papill/i) - papule = small, raised skin lesion less than 0.5 cm in diameter - parakeratosis = lesion characterized by thick scales, cracking and red raw surface caused by the persistence of keratinocyte nuclei in the horny layer of the skin - paronychia = bacterial or viral infection of the claw - patch = localized skin color change greater than 1 cm in diameter - pemphigus = group of immune mediated skin diseases characterized by vesicles, bullae and ulcers (pemphigus vulgaris) - petechiae = small, pinpoint hemorrhages (petechia) - plaque = solid raised lesion greater than 0.5 cm in diameter - pododermatitis = foot infection in animals, particularly birds, small mammals or rodents (bumblefoot or sore hocks) - polyp = growth from mucous membranes - pruritus = itching - purpura = condition characterized by hemorrhage into the skin that causes bruising (ecchymosis and petechia) - pustule = small, cicumscribed, pus-filled skin elevation (circumscribed) - pyoderma = skin disease containing pus (py/o, pus, purulent, puppy pyoderma, juvenile pyoderma, puppy strangles) - sarcoma = malignant neoplasm of soft tissue arising from connective tissue (sarc/o) - scale = flake - scar = mark left by a healing lesion where excess collagen was produced to replace injured tissue (cicatrix, cicatrices) - sebaceous cyst = closed sac of yellow fatty material - seborrhea = skin condition characterized by overproduction of sebum (oil) - skin tag = small growth that hangs from the body by stalks - ulcer = erosion of skin or mucous membrane (decubital ulcers, bedsores) - urticaria = localized areas of swelling that itch (hives) - verrucae = warts - vesicle = contained skin elevation filled with fluid that is greater than 0.5 cm in diameter (blister, bulla, bleb) - wheal = smooth, slightly raised swollen area that itches
Skin stratification Pages 244-246
- The skin is made up of three layers: the epidermis, dermis and subcutaneous layer - The outermost, or most superficial, layer of skin is the epidermis - The prefix epi- means above - dermis means skin - The epidermis is several layers thick and does not contain blood vessels - The epidermis is sometimes called the avascular layer - The epidermis depends on the deeper layers for nourishment - The thickness of the epidermis varies greatly from region to region in all animals. The thickest layers of the epidermis are found in the areas of greatest exposure, such as the foot pads and teats - The epidermis is made up of squamous epithelium and the basal layer - Squamous epithelium is composed of flat, platelike cells. Because these flat, platelike cells are arranged in many layers, this layer is called stratified squamous epithelium - The basil layer is the deepest layer of the epidermis - Keratin is a protein that provides skin with its waterproofing properties - The combining form for keratin is kerat/o (kerat/o also means horny or cornea) - Melanocytes produce and contain a black pigment called melanin - The combing form melan/o means black or dark - The absence of normal pigmentation is called albinism - The dermis is the layer directly deep to the epidermis (also called the corium) - The dermis is composed of blood and lymph vessels, nerve fibers and the accessory organs of the skin - Perception is the ability to recognize sensory stimuli - Tactile perception is the ability to recognize touch sensation - The dermis contains connective tissue, which is composed of the following cells: fibroblasts, collagen (-gen), histiocytes (macrophages) and mast cells (histamine, heparin) - The subcutaneous layer, or hypodermis, is located deep to or under the dermis and is composed of connective tissue - The subcutaneous layer contains a large amount of fat, or lipid. Adipocytes are fat cells that produce lipid - Adip/o is the combining form for fat - Table 10:1 Layers of the epidermis on page 245 - The epidermis has five layers (from dermis to most superficial); stratum means layer or sheetlike mass: 1. Stratum basale or stratum germinativum (cuboidal) 2. Stratum spinosum (keratinization, desquamation, prickle, spinous layer) 3. Stratum granulosum 4. Stratum lucidum 5. Stratum corneum (horny layer)
Glands Pages 246-247
- There are two main categories of skin glands: sebaceous and sweat glands - Sebaceous glands, or oily glands, secrete an oily substance called sebum - Seb/o is the combing form that means sebum or oily substance - ducts - ductules - holocrine glands - Sweat, or sudoriferous, glands are aggregations of cells located in the dermis - Sweat glands are divided into eccrine glands and apocrine glands - Eccrine sweat glands produce and secrete water, salt and waste (sweat) and are located in various regions of the body depending on the species - Aprocrine glands produce and secrete a strong-smelling substance into the hair follicles - Sweat glands help regulate body temperature against hyperthermia and hypothermia - Hidrosis is the production and excretion of sweat - hidr/o means sweat - Anhidrosis is the abnormal reduction of sweating - Hyperhidrosis is excessive sweating - Ceruminous glands are modified sweat glands that are located in the ear canal - The ceruminous glands secrete cerumen - Cerumen is commonly called earwax
Vestigial structures Pages 249-250
- Vestigial, or rudimentary structures of the integumentary system include dewclaws, chestnuts and ergots - Declaws are rudimentary bones - Chestnuts and ergots are vestigial pads in equine
Abbreviations related to the integumentary system
bx = biopsy DLE = discoid lupus erythematosus FAD = flea allergy dermatitis ID = intradermal PPD = purified protein derivative SLE = systemic lupus erythematosus SQ, SC, subq, subcu = subcutaneous
