Integumentary System
What integumentary structures are found in vertebrates? What are their functions? Skin (epidermis and dermis), scales, feathers, hair, glands, claws, nails, hooves, horns, antlers, vibrissae, baleen. Functions include protection, thermoregulation, sensory input, camouflage, waterproofing, and communication.
Describe the two main layers of the skin and their embryological origins. Know where these layers are in relation to subcutaneous tissue and underlying muscle. Epidermis: outer layer, derived from ectoderm, contains keratin. Dermis: inner layer, derived from mesoderm, contains collagen, nerves, blood vessels. Basement membrane separates them. Subcutaneous tissue lies beneath the dermis, above underlying muscle.
What is keratin? What are its properties, and in which chordates is it found? What are some examples of integumentary structures composed of keratin? Keratin is a fibrous structural protein providing strength and waterproofing. Found in reptiles, birds, mammals. Examples: scales, feathers, hair, nails, claws, hooves, horns, baleen.
What is the function of mucus secretions in fish? Mucus protects against pathogens, reduces friction for swimming, and aids in osmoregulation.
Describe the types of scales found in bony fish, including their composition and examples of fish that possess each type.
Cosmoid: thick dentin, thin enamel (lungfish)
Ganoid: thick enamel-like layer, no dentin (gars)
Teleost: lamellar bone only
Cycloid: smooth, concentric rings (salmon)
Ctenoid: toothed edge (perch)
How do the scales of cartilaginous fish differ from those of bony fish? Cartilaginous fish have placoid scales (dermal denticles) with pulp, dentin, enamel. Bony fish scales lack enamel/dentin and are derived from lamellar bone.
Which fish scales penetrate the epidermis? Placoid scales of cartilaginous fish penetrate the epidermis.
How do the scales of fish and reptiles differ in their embryological origin? Fish scales: dermal origin. Reptile scales: epidermal origin (folds of epidermis).
What are some unique characteristics of amphibian skin? Thin skin, lacks dermal scales, has capillary beds for cutaneous respiration, mucus and poison glands, chromatophores in dermis.
Describe the types of scales found in reptiles and their function. What are scutes? Be able to name the scutes of turtles. Reptile scales: epidermal folds, keratinized. Scutes: large epidermal scales with underlying bone. Turtle scutes: vertebral (center), costal (sides), marginal (edges), nuchal (neck), supracaudal (tail).
What is ecdysis? How does it vary among different reptile groups? Ecdysis is shedding of the outer keratinized epidermis. Snakes shed in one piece; lizards shed in patches. Dysecdysis is abnormal shedding.
What are the key features of avian integument? Thin epidermis, keratin scales on legs, feathers, no sweat/sebaceous glands (except uropygial gland).
What are the names for feather tracts and featherless areas between? Feather tracts: pterylae Featherless areas: apteria
What are the different types of feathers, and what are their functions?
Flight: thrust/lift
Tail: balance
Down: insulation
Contour: shape/aerodynamics
Semiplume: insulation/form
Bristle: sensory
Filoplume: display
Describe the structure of a flight feather. Know calamus, rachis, barb, barbule, hook, and vane. How and where are flight feathers attached to birds? Calamus (quill) anchors feather. Rachis is central shaft. Barbs branch off rachis. Barbules with hooks interlock to form vane. Primaries attach to manus; secondaries to ulna.
What are the different ways in which bird feathers acquire color?
Pigmentation: melanins, carotenoids, porphyrins
Structural color: refraction/scattering of light (iridescence, blues)
What is the uropygial gland, and what is its function? Preening gland at base of tail. Secretes waxy substance for waterproofing, conditioning, antimicrobial protection.
Describe the structure of hair and its location within the skin. Hair is a keratinous strand with shaft and root. Grows from epidermal follicle rooted in dermis.
Differentiate between guard hairs and undercoat hairs. Guard hairs: coarse, pigmented, visible. Undercoat: fine, numerous, insulate.
Name the three types of exocrine glands found in mammals and describe their secretions and functions.
Sebaceous: oily, waterproofing
Eccrine: watery, thermoregulation
Apocrine: viscous, scent/mammary/anal glands
Describe the different types of apocrine glands found in mammals and functions. Include sweat glands (non-human mammals), scent glands (territory/communication), mammary glands (milk), anal glands (defense/marking).
How do hooves, claws, nails, and talons differ in structure and function? All keratinized digit structures:
Hooves: encase digit, support weight
Nails: flat, protect tips (primates)
Claws/talons: curved, grasping/hunting
Compare and contrast horns and antlers, including their composition, growth patterns, and presence in males vs. females. Horns: keratin sheath over bone, permanent, both sexes (some species). Antlers: bone, shed annually, typically males only. Ossicones (giraffes): ossified cartilage.
What is baleen, and what is its function? Keratin plates from upper jaw gums in whales. Function as a filter-feeding strainer.
What are vibrissae and what is their function? Sensory hairs (whiskers), rooted deep in dermis. Detect touch/vibration, prominent in nocturnal mammals.
What is the basement membrane and where is it located? It separates the epidermis from the dermis, providing structural support and regulating cell movement.
What are chromatophores and where are they found? Pigment cells in the dermis of fish and amphibians. Responsible for coloration and camouflage.
What are iridophores and how do they produce color? Specialized chromatophores with reflective crystals. Produce structural colors via light refraction (e.g., chameleons).
What are plies in the dermis and what is their function? Distinct layers of collagen fibers that enhance flexibility, strength, and streamlining in aquatic species.