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69 Cards in this Set
- Front
- Back
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keratin |
a tough, waterproof protein that makes up scales, the outer sheaths of beaks and claws, and feathers; a main component of the epidermis, nails, hair, horns, and hooves
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dermatology
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the study of skin
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the skin
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prevents invasion of microorganisms, prevents drying out, prevents excess moisture intake, regulates body temp, receptor for senses, disposal of waste, vitamin d, dispose waste nutrients
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vitamin D
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a fat-soluble vitamin essential for life in most organisms; it enables the body to use calcium and phosphorus of healthy teeth and bones
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around the eyes
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thinnest skin tends to occur where?
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epidermis and dermis
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skin has two distinct layers
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epidermis
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this is composed of keratinized stratified squamous epithelium and dead cells and forms an outer waterproof shield; avascular but is provided nutrients via interstitial fluid that diffuses up from underlying dermis
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dermis
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makes up the majority of skin; only layer with blood vessels
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subcutaneous layer
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layer found below the dermis and composed primarily of adipose tissue, which acts as a thermoinsulator and a mechanical shock absorber
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divide in deepest layer and push up to form superficial layers
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cells do what in the epidermis?
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Shed; exfoliation
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what are superficial layers?
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keratinocytes
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cells that produce keratin
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melanocytes
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cells that produce melanin
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melanin
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a dark pigment stored in membrane-bound granules
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melanosomes
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membrane-bound granules
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Langerhands cell
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macrophage specific to the epidermis that originates in bone marrow and subsequently migrates to the skin
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merkel cells
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thought to aid in tactile sensory function, these cells are located in small numbers within the epidermal-dermal junction
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merkel's disk
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the junction formed by merkel's cells and sensory nerves
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squamous cell carcinoma
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a deadly form of skin cancer because it spreads rapidly to local lymph nodes and is aggressively invasive locally
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stratum basale
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basal layer; this layer consists of a single row of keratinocytes which are firmly attached to the epithelial basement membrane and are actively engaged in cell division
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stratum spinosum
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spiny layer; because when the cells of this epidermal layer are fixed for histological examination, they contract into spiculated masses that resemble sea urchins; this contains several layers of cells that are held together by demosomes
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stratum granulosum
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granular layer; the middle layer of skin; composed of two to four layers of flattened, diamond-shaped keratinocytes
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stratum lucidum
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clear layer; only found in very thick skin so most skin lacks this layer; microscopically appears as a translucent layer composed of a few rows of flattened, dead cells
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stratum corneum
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horny layer; the outermost layer and dominates the epidermis
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papillary layer
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this lies just beneath the epithelial layer of the epidermis and is composed of loose connective tissue with loosely woven fibers and ground substance
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dermal papillae
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nipplelike projections formed by the papillary layer of the dermis in most regions of the skin
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Meissner's corpuscles
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nerve endings or pain receptors and touch receptors; sensitive to light touch; in the dermis
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reticular layer
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consists of dense irregular connective tissue accounts for 80% of the dermis
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pacinian corpuscles
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a type of touch receptor in the hypodermis and is sensitive to heavier pressure
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pigmentation
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caused by the presence or absence of melanin granules in the armlike extensions of the melanocytes
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thick layers of fat and connective tissue
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what forms the foundation of the digital pads that bear weight of the animals?
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the insulating fat and tough outer skin of the paw pads form what?
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a protective barrier against abrasion and thermal variances, enabling the animal to walk on rough surfaces, hot roads, and cold snow
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exocrine sweat glands and lamellar corpuscles
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the paw pad is composed of what?
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planum nasale
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the top of the nose in cats, pigs, sheep, and dogs
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muzzle
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the top of the nose in horses and cows
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chestnuts
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usually dark brown and are found on the inside of each leg at the carpus (knee) of the forearm and at the tarsus or hock of the hind leg
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ergots
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similar to chestnuts but much smaller and are often overlooked because they are usually buried in the long, caudal hairs of the fetlock
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maintaining body temperature; coat color may also play a critical role in protecting the animal via camouflage
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hair plays an important role in what?
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hair shaft
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part of hair visible above the skin
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hair root
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portion of hair buried within the skin
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hair follicle
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hair is anchored by this, which is an invagination of the epidermis that extends from the skin surface to the dermis or occasionally the hypodermis
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hair bulb
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the deepest part of the hair follicle expands to form this
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papilla
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a mound of dermal cells at the base of the bulb which is covered with rapidly dividing epithelial cells
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matrix
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rapidly dividing epithelial cells covering the papilla
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shedding
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new hair growth influenced by genetics and environment
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root hair plexus
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a web of sensory nerve endings that envelop the hair root, making it an important touch receptor when the hair is bent
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compound follicles
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animals with fur often have these in which multiple hair strands emerge from a single epidermal orifice; as many as 15 hairs may be associated to one pore
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simple follicles
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a single hair grows from a single hair follicle
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primary hair
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also known as guard hair; is the topcoat; large, straight hairs predominant in complex hair follicles
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secondary hair
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also called satellite hairs; wool; wavy; smaller yet most numerous hairs in an animal's undercoat
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tactile hairs
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hairs sensitive to touch; face; whiskers; vibrissa
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arrector pili muscle
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a small, smooth muscle attached to each hair follicle and is innervated by the sympathetic nervous system; causes hair to stand up beyond the normal implantation angle
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sebaceous glands
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halocrin glands; located in the dermis and may be simple or complex alveolar structures; secrete sebum; lubricate skin and hair
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sweat glands
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also called sudoriferous glands and are found over the entire body of most domestic species, including pigs, horses, cattles, dogs, and sheep
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eccrine sweat glands
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excretory portion of this consists of a simple, coiled tube located in the dermis or hypodermis; connected to the surface by a long duct
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only in the deep layers of fat and in the connective tissue of footpads
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where are eccrine glands located in dogs?
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apocrine sweat glands
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these have a coiled, excretory portion buried in the dermis or hypodermis with a single excretory duct; glands empty into hair follicles
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in the external ear canal
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where are apocrine glands located in dogs?
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anal sacs
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famous for powerful, foul-smelling secretions; lined with sebaceous and apocrine glands and acts as a reservoir for the secretions that are produced from these glands; when animal defecates or becomes frightened, some or all of this area's contents are expressed, feces become coated with the secretions stored in this, and the unique smell of the animal is transferred to the environment
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defecation
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this serves the purpose of elimination, marking territory, and attracting a male
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mammary glands
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modified sweat gland; nurses young mammae; teat canal
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claw, nail, hoof
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these cover the distal phalanges
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claw
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hard, often pigmented outer coverings of the distal digits; important for maintaining good traction while running, walking, and climbing and serve as lifesaving tools for defense and for catching prey
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dewclaws
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remains of digits that have regressed in the course of evolution
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hoof
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technical name is ungula
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corium
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present in claws and hooves on the underlying sensitive tissue; firmly attached to the periosteum of the third phalanx and is rich with blood vessels that provide nutrients to the developing cells in the inner layers of the hoof
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the quick
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what is another name for the corium?
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digitigrade
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cats and dogs; individual pads on toes
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ungulates
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hoofed animals; cloven hoofed (2) - all but horse; horse as 1 |
