Integument Flashcards
Integument: structure and function
Integument= skin and epidermal derivatives
- Functions:
- protection
- temp regulation
- sensation
- elasticity
- prevent water loss
- immune function
- Structure:
- epidermis
- dermis
- subcutis- loose CT. loosely binds subdermis and dermis to organs/muscle below
examples: footpads, hooves, horns, anal sacs, mammary glands…
Thick skin vs. thin skin
Two types of skin
Thick skin
- thick epidermis
- hairless
- merocrine sweat glands
- ex. digital pads/ muzzle
Thin skin
- thin epidermis
- hair follicles
- sebaceous and sweat glands
Epidermis
Skin region: Epidermis
- Origin: ectodermal
- Structure:
- Epidermal pegs- connect down to dermis
- avascular
- Function:
- protect from and contact with outside
Dermis
Dermis
- Origin: mesodermal
- Structure: mainly CT
- Papillary layer- loose ct + type 1, 111 collagen
- Reticular layer- dense irreg ct + type 1 collagen
- dermal papillae-extend up into epidermis
- Function: supports epidermis
Epidermal layers (5)
Epidermal layers
- Stratum basale-active multiplication
- single layer of simple cuboidal cells
- attach to basal lamina (hemidesmosomes + desmosomes)
- Stratum spinosum- can multipy if needed
- cuboidal cells with spiny appearance
- desmosomes and tonofilaments= spiny
- cells are cohesive and resist abrasion
- Stratum granulosum- live but no mitotic activity
- keratohyalin granules
- lamellar granules
- nucleus and organelles dissapearing
- Stratum lucidum- nonliving
- present only in thick skin
- keratin filaments
- no organelles
- has eleidin protein
- Stratum corneum-non living (surface!)
- all keratin
- “horny cells”- looks like bricks and mortar kind of
- cells continually shed
Keratinaztion vs. cornification
*Most common cell in epidermis*
Keratinaztion:process by which keratinocyts differentiate (21days)
Cornification: production of stratum corneum by terminal epidermal differentiation
Epidermal cells: non-keratinocytes (3)
Epidermal Cells: non-keratinocytes
- Langerhans cells- immune system
- Location: stratum basale and stratum spinosum
- Origin: bone marrow
- Structure: intra-epidermal macrophages
- Function: immunological skin reactions
- Merkel’s cells- sensory cells
- Location: stratum basale (thick)
- Origin:
- Sturcture: free nerve endings at base of cells
- Function: mechanoreceptors.
- Melanocytes- produce melanin
- Location: stratum basale
- Origin: neural crest
- Structure: tyrosinase enzyme needed to produce melanin
- Function: produce melanin. send it to keratinocytes on surface. protects from uv radiation
Melanin: two types
Melanin
Protects against uv radiation
Eumelanin: brown/plack pigment
Pheomelanin: red/brown. responsible for red hair and freckles
NOTE: no tyrosinase=no melanin= albino!!!
Sensory Nerves of Dermis (2)
Sensory nerves of Dermis
Free nerve endings (stratum granulosum)
- Nociceptors- pain/itch/temp
Encapsulated nerve endings
- Meissners corpuscles
- Pacinian corpuscle
- Ruffini corpuscle (stretch)
Hair follicles and Hair
- Hair Follicle Structure:
- Dermal papilla- cary blood to cells of hair
- Root sheeth (outer to inner layer)
- glassy membrane
- external root sheeth
- internal root sheeth
- cuticle
- Hair Structure:
- medulla- loose cuboidal cells
- cortex- dense compact keratinized cells
- cuticle- single layer of flat keratinized cells
Hair follicles: 4 types
Hair follicles: types
Primary hair follicle:
- large diameter
- deep root
- sebaceous glands, sweat glands
- primary/guard hair
Secondary hair follicle:
- smaller
- root near surface
- sebaceous glands sometimes
- secondary/under hairs
Compound hair follicle: cluster of several hairs
- have one primary follicle and several secondary follicles
Sinus hair: “tactile hair”= whiskers
- sensory nerve
Identify
Sebaceous glands: secrete oily/lipid
- waterproofing and antibacterial
- ducts empty to hair follicle or skin surface
- remember: central nucleus, stain blue, foamy white
examples
- meibomian gland- huge gland in eye lid
- preen gland in birds
apocrine gland
apocrine gland: “sweat gland”
- epithelial cells with apical secretory caps
- simple sac/tube glands with coild or strait duct
- located throughtout skin
- functionality is usually communication (smell/mark)
examples
- mammary gland
- anal sac
- glands of moll (eyelid)
Hooves and Claws
Hooves and Claws
= modified layers of the stratum corneum
- no s. granulosum or s. lucidum
Hoof
Hoof
highly modified specialized skin that protects and encloses the end of digits in ungulate mammals.
Structure: epidermis and dermis(corium)
- epidermis= insensative laminae
- hoof capsule/wall
- dermis= corium
- perioplic corium
- laminar corium
- coronary corium
Identify: 5 layers
