Presentation on theme: "The Integumentary System ages/anatomy/skin.jpg."— Presentation transcript:
The Integumentary System ages/anatomy/skin.jpg
The Integumentary System Why purpose(s) does this system serve? *Preventing septicemia… *Preventing tetanic paralysis… *Preventing cancer… content/uploads/2007/06/wrinkles- beach.jpg 15% of adult human body weight
The Integumentary System Why purpose(s) does this system serve? *Preventing dehydration… *Preventing heat stroke and hypothermia… *Preventing failure to thrive…
The Integumentary System Why purpose(s) does this system serve? *Preventing lonely Friday nights… *Preventing gustatory delights… *Preventing ataxis…
Where does the skin come from? * * * *
The Dermis Comprised of Connective tissue… Fibroblasts and Fibers What are the most abundant fibers? How are they arranged?
What are plies, warps and weaves?
The Dermis Connective tissue layer… Bony and otherwise: Dermis of vertebrates has a predisposition to form bone. Calcium salts deposited on/around fibrous scaffolding of the dermis (dermal in origin) Generally consists of lamellar bone, cancellous bone, dentin and enamel-like surface Examples of tetrapods with dermal bone?!? _pages/xenarthra/armadillo_shell.jpg
The Dermis Dermal pigments: Most organisms have pigmented integument Responsible cells found in epidermis and dermis Pigment bearing cells/structures categorized based on color… Melanophores (melanin), Xanthophores (xanthin), Erythrophores (erythrin), Iridophores (guanine)
The Dermis Dermal pigments: Chromatophores can regulate dispersion of pigments altering color
The Dermis Dermal pigments: So how do you explain this?
The Epidermis General features of the epidermis: * Comprised of epithelial tissue * Avascular layer between environment and other tissues. * 2 types non-living coatings… 1) Mucus 2) Keratinized cells * Glandular… Unicellular in aquatics Multicellular in terrestrials
The Epidermis Epidermis of aquatic organisms: Fishes… Most glands single celled (goblet cells and granular cells). Some multicellular glands (hagfish and lungfish) Can be protective (alkaloids, toxins)
The Epidermis Epidermis of aquatic organisms: Aquatic amphibians… Mostly multicellular glands (mucous and granular) Land going amphibians have > [ ] of glands Can make sticky mucus for adhesion Mucous glands can hypertrophy to form nuptial pads
The Epidermis Epidermis of aquatic organisms: Most lack substantial amounts of keratin Cornified structures include: -“Teeth” of lamprey and hagfish -Stratum corneum of land-going amphibians -“Teeth” of tadpoles -Distal pads of digits
The Epidermis Epidermis of terrestrial organisms: Stratified layers gave rise to 2 categories of unique features… 1) Glands 2) Stratum corneum
The Epidermis Epidermis of terrestrial organisms: Glands fall in 2 main categories based on shape… 1) tubular 2) saccular
The Epidermis Epidermis of terrestrial organisms: Glands produce their secretions via 3 main modes… 1) Cell membrane (merocrine) 2) Whole cells and their contents (holocrine) 3) Cell fragments (apocrine)
The Epidermis Epidermis of terrestrial organisms: Mucous glands not abundant… occur in areas with need for lubrication Why not abundant on terrestrial animals? What other skin structures would interfere? What areas need lubrication?
The Epidermis Epidermis of terrestrial organisms: Granular glands found mainly in terrestrial amphibians and reptiles Can produce alkaloids and some pheromones Concentrations of “noxious” granular glands found on “warts” and parotoid glands of toads Lizards have femoral glands Musk or scent glands in turtles and snakes
The Epidermis Epidermis of terrestrial organisms (birds): Few integumentary glands in birds… however, avian oil glands Uropygial gland at rump, large in aquatic birds and some domestic birds Oil glands also line the ear canal Sometimes found around the vent
The Epidermis Epidermis of terrestrial organisms (mammals): 2 major types of glands in mammals… 1) Sebaceous (oil glands) 2) Sudoriferous (sweat glands)
The Epidermis Epidermis of terrestrial organisms (mammals): Sebaceous glands (saccular) usually associated with hair. Exceptions... Sebum secreted into hair follicle Modified (ceruminous glands) in ear canal to secrete cerumen Meibomian glands keep conjuctiva moist (plugged = chalazion)
The Epidermis Epidermis of terrestrial organisms (mammals): Sudoriferous glands (coiled tubular glands) Evaporative cooling primary function of merocrine sweat glands Found in least hairy regions Some mammals lack sweat glands Humans have greatest # per cm 2 Apocrine sweat glands involved with secondary sex characteristics
The Epidermis Epidermis of terrestrial organisms (mammals): Scent glands can be sebaceous or sudoriferous Found in varying locations… -Hooves -Anal canals -Forearms -Heads -Back -Eyebrows
The Epidermis Epidermis of terrestrial organisms (mammals): Mammary glands present in both sexes and derived from a line of ectoderm called the milk line This tissue invades the dermis and spreads Distinct tissue above these glands develops (nipple)
The Epidermis Epidermis of terrestrial organisms (mammals): Nipples can be multiple… -Axillary -Thoracic -Abdominal -Inguinal Different species… different placement
The Epidermis Epidermis of terrestrial organisms (mammals): During lactation, products accumulate in cysterns (usually) Suckling releases milk and oxytocin facilitates by causing smooth muscle contractions “Let down” reflex
The Epidermis Stratum corneum: Epidermal scales found only in amniotes. Squamates (snakes & lizards) thickened corneum except at “hinge” areas Varying forms… cycloid, spiny, granular, scutes Birds have epidermal scales on areas lacking feathers What about mammals?
Thick skin Stratum corneum: The Epidermis
Claws, hoofs and nails: Claws appeared in basal amniotes Tigers have claws… are they homologous to those of Idaho Giant Salamanders?
The Epidermis Claws, hoofs and nails: Claws, nails and hooves homologous Similar structure… *Unguis *Subunguis *Cuneus (frog) Birds can have claws on wings too Are claws shed or worn down?
The Epidermis Feathers: 3 basic types… *Countour feathers *Plumules *Filoplumes Feathers comprised of a quill (calamus), shaft and vanes. Parallel extensions from the shaft barbs are crosslinked with barbules (hooklets and flanges)
The Epidermis Feather development: Dermal papilla induces overlying stratum basale to divide mitotically… resulting bump is called feather primoridium Why is presence of papillary vasculature important? Tall columns form a feather sheath and push toward tip, becoming barbs
The Epidermis Feather development: When the barbs are still in protective feather sheath it is called a pin feather At feather maturity… bulk of papilla dies back Basale tissue retracts and then starts over again Developing feathers push old feathers out Blood feathers
The Epidermis Feather origins: One hypothesis is that they are derived from reptile scales… Sinosauropteryx Early development of dermal papilla is similar but remaining scenario is not Some propose they are novel structures
The Epidermis Hair: Functions of hair… Thermoregulatory (underfur and guard hairs) Sensory (vibrissae) Protective (spines and quills)
The Epidermis Hair morphology: Similar to feathers in that there is a dermal papilla Hair bulb has stratum basale with much mitosis Hair root is portion under the dermis where cells are dying Hair shaft is portion of hair that is separate from follicle wall
The Epidermis Hair morphology: Thin outer covering is the cuticle Underlying zone called cortex Inner pith is the medulla Smooth muscle associated with the follicle and originating in the dermis is the arrector pili
The Epidermis Horns: *Bovine horns and pronghorns *Hair horns *Antlers and giraffe horns
The Epidermis Baleen and miscellaneous: *Toothless whales (mysteceti) rely on baleen to filter fish and/or crustaceans (krill) *Rattlesnake rattles *Beaks and combs *Ischial callosities *Knee pads *Tori & apical pads oon_showing_ischial_callosities.jpg photos/diapsids/rattlesnake_rattle.jpg
Integuments by Taxa Agnathans: Epidermis… stratified, unicellular glands, mitotically active throughout Dermis… thinner than epidermis but dense/tough
Integuments by Taxa Cartilaginous fishes: Epidermis… stratified, multicellular glands show up Dermis… placoid scales and melanophores
Integuments by Taxa Bony fishes: Epidermis… many mucous glands Dermis… dermal bone/scales
Integuments by Taxa Amphibians: Epidermis… stratified, multicellular glands (mucous and granular) Dermis… attached to musculature in some, loose in others, presence of chromatophores
Integuments by Taxa Non-avian reptiles: Epidermis… stratified, thick stratum corneum (scales) Dermis… tough, some with dermal bone
Integuments by Taxa Birds: Epidermis… thin, lacks glands (except uropygial), modified epidermal layers to form feathers (scales) Dermis… thin, arrector pili muscles
Integuments by Taxa Mammals: Epidermis… Distinct strata, variety of glands, hair Dermis… exceptionally thick and tough