Flashcards in Integument Deck (75):
List 5 epidermal derivatives
foot pads, claws, hooves, horns (but not antlers), anal sacs/glands, mammary glands, uropygial glands, wattles, spurs, feathers
protection, prevent water loss, temperature regulation, sensation, immune functino, excretion, water-ion balance (sweating), calcium homeostasis, energy storage
functions of hair
insulation, camouflage, social display, sensory, protection
what are the 3 layers of the skin?
epidermis, dermis, and hypodermis
epidermis is made of
stratified squamous keratinized epithelium
what are the two layers of dermis
papillary and reticular layers
hypoddrmis/subcutis is sometimes rich in what? What does the hypodermis attach to?
-rich in adipocytes
-attaches loosely to organs
what layer of skin is thick skin? what are some other characteristics of thick skin?
-hairless, merocrine sweat glands present, ie. digital pads, muzzles
what layer is thin skin? name some characteristics
thin skin is part of the epidermis
-hair follicles with arrector pili muscles, sebaceous and sweat glands
[thick vs thin skin picture]
[epidermal pegs picture] what are the names of these structure, and where is it found?
1. epidermal pegs: downward projections of epidermis into the underlying dermis
2. dermal papillae: upward projections from dermis
-footpad, nasal planum, scrotum; found at areas subject to traction stress
dermal papillae function
increase area of contact between dermis and epidermis
-bring blood vessels near epithelium
what is the main component of dermis?
Papillary layer: what type of connective tissue is it made of? What type of ollagen? What other chatacteristics does it possess?
-type 1 and 3 collagen
-mast cells, macrophages, vessels, and nerves
[insert picture of papillary and reticular layers]
Reticular layer: type of connective tissue, type of collagen, and other characteristics
-dense irregular ct
-type 1 collagen
-network of elastic fibers, blood vessels, and nerves
skin elasticity refers to what in the dermis?
the network of elastic fibers present in the reticular layer [insert skin elasticity picture]
cells of the epidermis can fall into one of two categories:
keratinocytes or non-keratinocytes
most common cell type of the epidermis: they make up 95% of the epidermis
-langerhans cells - part of immune system
-merkel's cells - sensory cells
-melanocytes - protective
adhere cells of the epidermis include
desmosomes between cells and hemidesmosomes attaching to the basal lamina
epidermal layers are constantly replacing...
cytoplasm with keratin, to continually add to the outer layer
layers of the epidermis include [picture of layers of epidermis]
[picture of stratum basale]
-single layer of cuboidal-columnar cells
-rests on basal lamina, possesses hemidesmosomes and desmosomes
-melanocytes may be present
[picture of adhere cells]
1. adherens junctions
2. keratin filaments
stratum basale function
-mitotic division allows new cells to move up to keratinize on upper layers
[pictures of stratum spinosum]
-what is this layer called and what are its characteristics?
-cuboidal or slightly flattened
-in thin skin there are 1-2 layers, in thick there are many
-desmosomes give spiny appearance (aka prickle cells layer)
-cohesive cells that resist abrasion
-layer retains some mitotic capability if needed
[pictures of desmosomes]
what are these structures?
-3-5 thin layers, may be hard to see
-possesses keratohyalin granuales
-no mitotic activity; it is the last living layer, last to have nucleus and organelles
-has lamellar gramules
-secreted by cells to form waterproof lipid sheets aka intercellular cement
-translucent lyaer present only in thick skin
-many keratin filaments and desmosomes present
-cells fully keratinized
-cytoplasm contains eleidin, protein related to keratin
-have pyknotic nuclei
what is the last living layer of epidermis?
-15-20 layers thick ie. footpad
-cells made of keratin
-known as horny cells surrounding thicker plasma membrane and lipid matrix aka bricks and mortar
-cells continually shed at surface
keratin is a...
water resistant protein forming a barrier against external environment
non-nucleated cells of the epidermis are...
dead, keratinized cells
keratinization vs cornification
-keratinization is process of keratinocytes differentiating, takes about 21 days for dog
-cornification is the production of stratum corneum
langerhans cells are found in what layers of epidermis? From what cells are they derived? What is their function?
-stratum basale and stratum spinosum
-derived from bone marrow monocytes
-function as antigen presenting cells to process surface bound antigens and present them to T lymphocytes
[picture of langerhans cells]
[merkel's cells picture]
-found in thick skin near stratum basale
-sensory mechanoreceptors for cutaneous sensation and neuroendocrine system
-free nerve endings found at their base
-where are theses structures found?
-t/f: they are short lived?
-what is their function
-False: they are long lived, stable cells
-produce melanin, are present in stratum basale and spinosum
-melanin protects cells from UV radiation
what must be present for melanin to functinon properly?
-how does melanin work?
-melanin transforms energy into harmless heat, stopping uv radiation from generating free radicals in cells
what is the most common type of melanin?
eumelanin: brown black pigment
what is pheomelanin
-red brown polymer responsible for red hair and freckles
what causes albino animals?
-no tyrosinase means no melanin can be produces
what type of nerve endings sense pain, itch, and temperature, and where are they found?
-nociceptors, found in the stratum granulosum
-meissner's corpuscles, a type of nerve ending
name the layers of the hair follicle
external glassy membrane, external root sheat, internal rooth sheat, cuticle, and dermal papilla
what are the three layers of hair, from inner to outer?
medulla, cortex, cuticle
This hair layer has loose cuboidal cells, with air filled in areas
medulla, the inner layer of hair
this hair layer is made up of a single layer of flat keratinized cells
hair cuticle, the outer layer of the hair
this hair layer is made of dense keratinized cells parallel to hair shaft
dermal papilla functions
carries blood supply to the cells of the hair
-hair's matrix cells comparable to stratum basale
external glassy membrane is equivalent to what part of the epidermis? Which layer is this layer external to?
-external to the external root sheath
external root sheath is continuous with the...
internal root sheath consists of layers of what cell shape
why are hairs so difficult to pull out?
the cuticle has keratinized cells with free edges oriented towards the hair bulb, while the hair cuticle has cell edges oriented in the opposite direction
primary vs secondary hair follicle
Primary: large diameter, rooted deep in dermis, possess sebaceous glands, arrector pili mucsle, and sweat glands
Secondary: smaller diameter, rooted nearer the surface, +/-sebaceous gland, no sweat glands, and no arrector pili muscle
guard hair is another name for
primary hair follicle
under hair is another name for
secondary hair follicle
compound hair follicle
clusters of hair follicles, as opposed to just one
-follicles merge at the sebaceous gland and emerge from one external orifice
-usually made up of a single primary follicle and many secondary hair follicles
whiskers of a cat or dog are properly called...
-what makes them different from other hair types?
sinus hair or tactile hair
-differ due to the nearby sensory nerves that are stimulated when the hair moves, and the surrounding blood-filled venous sinuses
sebaceous gland function
-produce sebum - a mix of lipid and disintegrated cells
-act as an antibacterial and waterproofing agent
-ducts empty into hair follicle or skin surface
name some special types of sebaceous glands
-supracaudal glands in dogs, mental glands in cats, horn glands in goats, circumanal glands in ruminants, preputial glands in horses, uropygial/preen glands in birds
sweat glands are found where in domestic animals; what is their function?
throughout most of the skin
-function mainly for communication, be it attraction or marking
horses produce sweat for...
-a major component of horse sweat is...
thermoregulation - a major component of which is latherin
most sweat glands associated with hair follicles perform what type of secretion
t/f dogs produce sweat for thermoregulation
false: though merocine glands in foot pads secrete watery solution similar to human prespiration
-apocrine glands at hair follicles in dogs function to seal the outer layer of epidermis and to secrete pheromones
name other specialized sweat glands
-glands of moll (eyelid tear glands)
-apocrine glands of anal sac
-ceruminous glands (ear wax)
What tissue are hooves and claws a modification of? what do they lack?
-mod of skin; variation of stratum corneum
-lack stratum granulosum and lucidum
what are the two layers of the hoof
outer epidermis and underlying dermis aka corium
insensitive laminae is made of epidermis or dermis
epidermis (hint: epidermis is avascular)
coronary and laminar corium (sensitive laminae) are made of epidermis or dermis
dermis: corium contains nerves and vascularture
what are the three epidermal layers of the hoof?
-thin layer known as the glaze
-continuation of the perioplic epidermis
-main supportive layer
-tubular and intertubular horn produced by stratum basale/spinosum of coronary groove