Integumentary system Flashcards
(37 cards)
What are the elements of the integument?
Skin, scales, hair, feathers, antlers, horns, claws, nails, glands, sensory perception
What are the three layers of skin in vertebrates?
Epidermis from ectoderm
Dermis from mesoderm
Hypodermis from endoderm
Which layers of the integument give rise to which structures?
Epidermis: baleen, claw sheaths, nails, horn sheaths, bill sheaths, some scale types
Dermis: dermal bones and osteoderms: bony deposits
Interaction of both: hair, feathers, teeth, denticles, fish scales
Which integumentary structures are the result of interactions between epidermis and dermis? In which lineages of vertebrates do we find these structures?
Hair + mammary gland (mammals)
Feathers (birds)
Teeth (vertebrates)
Denticles (sharks)
Fish scales
What are general features of the epidermis?
Often produces mucus
- In fish: protection against bacteria and aids in streamlining
- In amphibians: helps to keep skin moist
Vertebrates: stratum corneum
Stratum corneum
Tetrapod innovation
Keratinized/cornified layer
Protection against abrasion and desiccation, produces specialized structures by keratinizing system (hooves, horns, sheaths, hair)
What are general features of the dermis?
Dermal bones: plates of intramembranous bone formed within dermis, in ostracoderms
Main component of dermis: fibrous connective tissues
What are chromatophores? From which embryonic cell population do chromatophores arise?
Vertebrate pigment cells
Chromatocytes in amniotes
Formed from neural crest cells
What are the different types of chromatophores?
Melanophore: black/brown pigment cell
- Melanin: pigment
- Eumelanin: black/brown hue
- Pheomelanin: yellow/reddish hue (not in fish)
- Melanosome: melanin-producing and -storing organelle
Xanthophore: yellow-orange pigment cell
- Pteridine: pigment
- Xanthosome: pteridine-producing and -storing organelle
Erythropore: reddish pigment cell
- Carotenoid: reddish pigment of erythropore (from food)
- Erythrosome: carotenoid-storing organelle
Iridophores: metallic-reflective cells
- Organelle: reflective platelets
- Contain crystalline purine (guanine)
Which group of vertebrates have the most types of chromatophores? The least?
Most: fish
Least: birds/mammals
What are the functions of the integument?
Protection: physical barrier, UV protection
Water balance: prevents water loss/gain, water gain in amphibians
Maintenance of body temp: gain in reptiles, conservation in endotherms
Stimulus perception: temp, touch, pressure, pain
Coloration: communication, camouflage
Excretion: water, salts, waste
Secretion: oil, milk in mammals
Locomotion and prey capture
Vitamin D synthesis
Respiration
What are scales? Differentiate dermal from epidermal scales.
Integumentary folds
Dermal scales (fish): mostly dermal contribution, ossified dermal bone
Epidermal scales (reptiles): epidermal fold, thickened keratinized layer
How does mucus benefit fish?
Protects against bacteria
Helps create laminar surface flow
Creates slippery anti-predator surface, includes defensive chemicals
Do agnathans have scales?
Smooth, unscaled surface
Epidermis: stacked layers of living cells
What are the differences between placoid, ganoid, cycloid and ctenoid scales? Give an example of a vertebrate that has each type of scale.
Ctenoid (bass): bone only
Cycloid (salmon): bone only
Ganoid (gar): bone w/ enamel
Placoid (shark): denticles
Which characteristics distinguish tetrapod integument from that of fishes?
Much more keratinization in tetrapods than fishes
Produces stratum corneum
Lipids often co-occur with keratinization to avoid desiccation
Multicellular glands common in tetrapod integument
What is a major issue associated with amphibian integument? How do amphibians counteract this issue?
Subject to desiccation
Seek out moisture in habitat
Posture
What are the two main kinds of skin glands in amphibians, how do they differ, and why are they adaptive?
Mucous gland: small cluster of cells that relate product into common duct
Poison gland: often store secretions
Amphibian integument
No scales (stratum corneum very thin when present)
Cutaneous respiration
Subject to desiccation
Mucous + poison glands
Toepads
Non-avian reptiles integument
Much more extensively keratinized than amphibians
- Both beta and alpha keratin as in birds
Fewer skin glands than amphibians (mostly scent)
Epidermal, not dermal scales
Dermal bone (osteoderms): crocs, some lizards
How do reptiles undergo ecdysis, and how does it differ between groups?
Three layers
At ecdysis, stratum granulosum (inner) and stratum corneum are duplicated by stratum basale
Older layer of skin sloughs off
- In bits in crocs and turtles
- In sheets or entire skin in lizards and snakes
What are the general characteristics of avian integument?
Skin weakly keratinized, loose
Epidermis thinner than dermis
Dermis highly vascularized with many sensory nerve endings and smooth muscle
- Relatively thick
What is the major avian integumentary gland and what is its function?
Uropygial/preen/oil gland
- At upper tail base
- Produces oil for feather maintenance
- Waterproofing,
- Promotes flexibility
- Inhibits feather-degrading bacteria
What are the major characteristics of feathers?
Mature feather is a non-vascular, non-nervous epidermal product
Extremely tough and flexible yet lightweight
Occur in tracts (pterylae)
Entire feather coat is the plumage
Replaced annually or 2-3 times/year via molting
