Integumentary System Flashcards
primary role of the integument
protection
protects the internal organs from mechanical injury
Dermal armors
secrete slimy or noxious substances
Glands
provide protective coloration
Serves as barrier to the rays of the sun
Pigments
Exteroceptive Role of the integument
Protective in its most primitive state
Naked nerve endings are stimulated when foreign objects contact the skin
The only role of cutaneous receptors in agnathans
More complex receptors are found in other fishes and tetrapods and highly used for survival
Some Roles of the Integument
Protective Role
Exteroceptive Role of the integument
Respiration
Excretion
Thermoregulation
Locomotion
Maintenance of Homeostasis
Nourishment
Pheromones
Skin Coloration
Roles of the Integument
Naked nerve endings are stimulated when foreign objects contact the skin
The only role of cutaneous receptors in agnathans
More complex receptors are found in other fishes and tetrapods and highly used for survival
Exteroceptive Role of the integument
Roles of the Integument
Supplements gills and lungs of many amphibians (aquatic urodeles)
Respiration
Scales and cornified epithelium are not conducive for cutaneous respiration
true
_____________ rely its respiration entirely on the skin (they don’t have gills or lungs)
Plethodontid salamander
Roles of the Integument
CO2 excretion in some aquatic amphibians
Sweat glands are supplementary to excrete nitrogenous wastes
Ammonia in fishes is easily diffused via gill epithelium and other tissues exposed to water
Excretion
Roles of the Integument
Function of the skin of endotherms (birds and mammals)
Fur and feather insulate against cold
Sweat cools by evaporation
Thermoregulation
Dilation of blood vessels within the dermis heat loss by radiation
increases
Roles of the Integument
Performed by adhesive pads, claws that assist in climbing, scutes that assist in slithering and feathers that provide airfoil
Webbed feet for those that wade in water
Webbed wings in bats enable them to fly
Locomotion
Roles of the Integument
Reservoirs of calcium and phosphate molecules in fishes
Cornified epithelium of tetrapods conserve water
Absorbs water under the influence of posterior pituitary gland in aestivating lungfishes, toads and other craniates
Maintenance of Homeostasis
Roles of the Integument
Mucus secreted in some teleosts provide nutrition to hatchlings
Mammary glands provide nourishment to the young
Maintenance of Homeostasis
Roles of the Integument
Serves as species identification or serves as alarm
Elaborate colorations help during breeding season
Can be used as protection
Pheromones and Skin Coloration
Forms the interface between the animal’s internal environment and the outside world
Integument
Contains epithelial, connective adipose and smooth muscle tissues
Also contains blood vessels, glands, sensory receptors, nerves and other structures
Integument
Superficial part of skin; stratified squamous epithelium; composed of four or five strata
Barrier that prevents water loss and the entry of chemicals and microorganisms; protects against abrasion and ultraviolet light; produces vitamin D; gives rise to hair, nails, and glands
Epidermis
Most superficial strata of the epidermis; 25 or more layers of dead squamous cells
Provision of structural strength by keratin and protein
envelope within cells; prevention of water loss by lipids surrounding cells; sloughing off of most superficial cells resists abrasion
Stratum corneum
Three to five layers of dead cells; appears transparent; present in thick skin, absent in most thin skin
Dispersion of keratohyalin around keratin fibers
Stratum lucidum
Two to five layers of flattened, diamond-shaped cells
Production of keratohyalin granules; lamellar bodies release lipids from cells; cells die
Stratum granulosum
A total of 8 to 10 layers of many-sided cells
Production of keratin fibers; formation of lamellar bodies
Stratum spinosum
Deepest strata of the epidermis; single layer of cuboidal or columnar cells; basement membrane of the epidermis attaches to the dermis
Production of cells of the most superficial strata; melanocytes produce and contribute melanin, which protects against ultraviolet light
Stratum basale
Deep part of skin; connective tissue composed of two layers
Responsible for the structural strength and flexibility of the skin; the epidermis exchanges gases, nutrients, and waste products with blood vessels in the _______
Dermis
Papillae project toward the epidermis; loose connective tissue
Brings blood vessels close to the epidermis; dermal papillae form fingerprints and footprints
Papillary layer
Not part of the skin; loose connective tissue with abundant fat deposits
Attaches the dermis to underlying structures; fat tissue provides energy storage, insulation, and padding: blood vessels and nerves from the subcutaneous tissue supply the dermis
Subcutaneous tissue
Composed of a stratified epithelium which developed from embryonic ectoderm
Epidermis
consists of 1 to 2 mitotically active, cuboidal cell layers located above the basement membrane
Cells move toward the body surface to differentiate and are eventually sloughed off
Stratum germinativum
Mat of collagen and elastin fibers; dense irregular connective tissue
Main fibrous layer of the dermis; strong in many directions; forms cleavage lines
Reticular layer
Composed of a stratified epithelium which developed from embryonic ectoderm
Epidermis
Some epidermal cells synthesize _________ which is a water-insoluble, horny protein that may fill the cells and replace other organelles
kertain
animals that have a thin layer of epidermis
Fishes and amphibians
Epidermis Two types of covering:
Aquatic craniates -
Terrestrial craniates - water-impervious cornified cells
animals that have a thick layer of epidermis
Reptiles and mammals
which is a water-insoluble, horny protein that may fill the cells and replace other organelles
stratum corneum
Epidermis covering that has a thin coat of mucus
Aquatic craniates
Epidermis covering that is mostly multicellular
Terrestrial craniates
Develops from mesenchymal cells which are mostly derived from mesodermal dermatome of somites
Dermis
Basic component is collagen and elastic fibers embedded in proteoglycans and other macromolecules which holds other component in place and provide tensile strength
Dermis
Other components of dermis
blood vessels, small nerves and pigment cells
Lymphatics
Naked and encapsulated exteroceptors
Bases of multicellular glands
Bases of hairs or feathers and their erector muscles
is thicker than the epidermis in mature skin and consists of two layers:
Irregularly arranged collagen fibers
Dermis
Dermis consists of two layers:
Stratum laxum
Stratum compactum
Teeth, bony and horny scales, feathers and hair develop as a result of intricate interactions between the dermis and epidermis via neural crest cell migration
Skin Derivatives
Glands, feathers, hair and other keratinized structures are composed of __________ in which some parts invade the underlying dermis
epidermal cells
Superficial bones are dermal derivatives
true
Teeth and bony scales are of ______ and _____
epidermal and dermal products
These structures have supportive and protective functions that they are sometimes termed as
integumentary skeleton
Cells that contain pigments found in all vertebrates except albinos
Develop from neural crests and are located in the upper part of the dermis in fishes, amphibians and reptiles
They penetrate and are located in the epidermis of birds and mammals
Chromatophores
Star-shaped cells containing melanin
With long, branching processes
granules may either be black, brown or more yellow and reddish
Melanophores
Melanophores contained within cellular organelles called
melanosomes
is synthesized within melanophores of birds and mammals but most of it is transferred to feather, hair and other epidermal derivatives
Melanin
in anamniotes and reptiles may migrate into processes of the melanophores, maximizing the color or concentrating it
Melanosomes
Contain crystalline chemochromes from guanine
Generate iridescent colors because of the diffraction of light within the stacked plates
Iridophores or guanophores
Utilize crystalline purines (often guanine) to reflect light
Produce reflective white hues
Leucophores
Contain yellow pigments composed of pteridines
Xanthophores
Contain reddish pigments composed of carotenoids
Erythrophores
Vesicles containing pteridine and carotenoids are sometimes found in the same cell
true
Unique copper uroporphyrin pigment responsible for the bright green coloration of several birds of the family Musophagidae, most notably the turaco
The only true green pigments found in birds
Turacoverdin
Naturally occurring red pigment
Found only in the bird family Musophagidae, the turacos
Turacin
Important Roles of Skin Coloration
Can be concealing or cryptic helping an animal hide from predators or enable a predator to stalk a prey
Can be aposematic where it advertises the presence of dangerous, venomous or distasteful species
Also used for species recognition, establishment of territories, courtship and other types of communication
Also help reptiles thermoregulate
is similar in its basic structure
Epidermis is relatively thin and most cells are alive
Surface cells are covered with microridges that increase the surface area for exchange between the animal and its environment
Fish Integument
may be deposited in limited areas such as horny teeth of cyclostomes and tubercles that develop in many fishes during mating season
Keratin
secrete only mucus in fish
Goblet cells
secrete mucus and additional ingredients mostly of unknown functions in fish
Granular cells
_________ which are products of granular cells are not common in fish
Alkaloids
glads that are not abundant in fish
Multicellular glands
_______ can be for protection, for nutrition and some contain toxins
Slimy mucus
in fish, Light-emitting organs in deep-sea teleosts
Upper part of the gland consists of modified mucous cells acting as magnifying lens
Beneath the lens are light-emitting cells
Cells below are in contact with melanophores and in blood cells which is the source of raw materials
The light is not intense and usually of many hues
Photophores
light from Photophores components
Luciferase + luciferin =
Functions for Photophores
Species and sex identification
Lure for prey in carnivores or is a warning that it is a carnivore
Concealment by countershading
Highly mitotic, multi-layered epidermis with unicellular mucous glands
No keratinized or cornified layer
Horny denticles on buccal funnel or teeth are the only keratinized structures
Epidermis of Agnathans
Multi-layered than agnathans
Not as much unicellular glands except in chimeras
Localized glands include:
Goblet cells
Multicellular glands
Photophores in the dermis are modified epidermal glands that lost connection with the epidermis
Epidermis of Cartilaginous Fishes
Collagen fibers are generally more regularly arranged than of other vertebrates
Develop in layers that spiral around the body in approximately 45o angle to the longitudinal axis with adjacent layers perpendicular to each other
Fiber arrangement strengthens the skin so that body shape is maintained during swimming
dermis of Cartilaginous Fishes
dermis acts as ___________ transmitting muscular force in sharks
exotendon
Bony Dermis of Fishes Generalized pattern:
4 = enamel or enamel-like substance
3 = dentin (denticles is 3 + 4)
2 = vascular spongy bone
1 = lamellar bone
Dermal Scales
Placoid
Rhomboid
Cosmoid
Ganoid
Elasmoid
Ctenoid
Cycloid
Dermal Scales
Elasmobranchs
Placoid
Dermal Scales
Dentine crown with a pulp cavity and covered by enameloid/enamel
(ameloginin proteins)
Placoid
Dermal Scales
Osteichthyans
Rhomboid
Dermal Scales
Fossil sarcopterygians
Cosmoid
Dermal Scales
Layer 4 is composed of ganoine, a form of ename
Ganoid
Dermal Scales
Specialized canal system associated with dentine and enamel, not a tissue but a structural complex
Cosmoid
Dermal Scales
Actinopterygians
Ganoid
Dermal Scales
Teleosts
Elasmoid
Ctenoid
Cycloid
Dermal Scales
Thin lamellar bone that may be associated with a fibrous plate
Elasmoid
Dermal Scales
Possesses small spines (ctenii), a derived scale
Ctenoid
Dermal Scales
Composite group of ctenoid-like scales lacking spines
Cycloid
No dermal bone
Thinner than epidermis
Tough due to collagen connective tissue
With many melanophores
With slime glands
Dermis of Agnathans
No dermal bone
Surface denticles (placoid scales) present except in chimeras
Thicker than the epidermis
With melanophores (more dorsally)
Dermis of Cartilaginous Fishes
Cosmoid and ganoid in basal actinopterygians and neopterygians (Polypterus and garpikes)
Cycloid and ctenoid in modern fishes
Dermis of Bony Fishes
relatively thin but epidermal cells synthesize keratin
As it accumulates, cells die and the stratum corneum is formed which is seldom more than 1 to 2 layers thick to allow cutaneous respiration
Desquamated periodically and is hormonally controlled
Not sloughed off in toads and they just continually pile up
Desquamated periodically and is hormonally controlled
Not sloughed off in toads and they just continually pile up
Highly glandular
Glandular glands aid in survival of land-adapted anurans
Transitional between those that spend more time and more on land
Cornified appendages are rare
Amphibian Epidermis
loss of bits of outer skin by peeling or shedding or coming off in scales
Desquamated
Amphibian Epidermal Glands
Mostly multicellular mucous or granular glands
In Amphibianw, _____ on digits serves as holdfasts in trees or glands on thumbpads during breeding season serves as restraint for females
Glands
___________ amphibians have the most number of multicellular glands
Secretions keep the skin moist when they are on land
Tailed aquatic
Present in toads
Secrete irritating alkaloids which are defensive in nature or pheromones used during breeding
Restricted to a localized area of the body
Granular Glands
Keratin in amphibians is shown by
Aquatic urodeles have thin desiccation-impending stratum of cornified cells
Anurans tadpoles have horny tooth like structures which is shed during metamorphosis
Firmly attached to underlying muscles in apodans and urodeles
Anurans have lymph sinuses separating it from muscles
Dermal chromatophores in other species can elicit color change
Bony scales (osteoderms) present in head of caecilians and a few tropical toads at the back
Dermis in amphibians
Represents the ultimate adaptation of craniate skin for surviving in an arid and hostile environment
With many localized modifications: horny scales, scutes, beaks, rattles, claws, plaques and spiny crests found on the stratum corneum
Granular glands are found in some region only
Reptile Epidermis
Repetitious thickenings only found in amniotes
Disposed on overlapping folds of the epidermis in squamates where thinning at scale joints allow for movement
Scutes are large, thin, polygonal scales
Epidermal Scales
the dermis of Reptiles has dermal bone
true
the dermal bone of turtles
carapace, plastron and lateral bridges
Soft-shelled and leatherback turtles lack
dermal ossification
the dermal bone of Crocodiles and some lizards
osteoderms in localized regions of the body (gastralia in ventrolateral abdominal wall)
the dermal bone of snakes
absent
Scales only present at the feet and base of the beak
Claws are present on the toes and one or two on digits of the wings
Avian Epidermis
Glands are generally lacking in avians except:
Uropygial glands
Oil glands
glands at the tail base for preening
Uropygial
glands at outer ear canal of domesticated birds
Oil glands
Prominent swelling at the rump behind the pygostyle
Largest in aquatic birds and in domestic fowl
Oil which is water-repellent is used for preening
Uropygial gland
are found in outer ear canal and sometimes in the vent area
Smaller oil glands
Feather types
down feather
contour feather
filoplume
Development of a Feather
Dermal Papilla is formed
Feather Primordium is induced
DP becomes vascularized or Feather Follicle develops as FP elongates
from Feather Primordium,
Growth Zone develops at the base of the FF giving rise to the feather sheath
FS splits open as the shaft elongates to full growth
from feather sheath
DP dies when the feather is fully grown and becomes pulp as the Inferior Umbilicus is formed
Supports feather follicles and erector, depressor, retractor and rotator muscles
Dermis of birds
are cornified appendages first developed for insulation and is a modified scale
Feathers
No osteoderms in birds except for ___________
gamecocks
Stratum germinativum - basal layer
Stratum granulosum - with keratohyaline
Stratum corneum - highly keratinized
Give rise to scales (armadillos and pangolins), claws (hoofs and flat nails) and horns
Thickest on parts of appendages in contact with surfaces (palms, hooves, feet)
Stratum lucidum - present in palm and sole
Mammalian Epidermis
Hair are _________
includes horns, pronghorn, antlers, baleen of whales and epidermal scales
cornified epidermal appendages
________ are present in most mammals and can be modified as nails in primates or hooves in ungulates
Claws
Epidermal Glands
based on Structure
Tubular
-Simple
-Branched
-Coiled
-Compound
Alveolar
-Simple
-Branched
-Compound
Epidermal Glands
based on Substance secreted
Mucous
Granular
Avian oil
Sebaceous
Sweat
Scent
Mammary
Epidermal Glands
based on Mode of elaboration
Merocrine
Apocrine
Holocrine
Cells of the gland produce secretions by active transport or produce vesicles that contain secretory products, and the vesicles empty their contents into the duct through exocytosis.
Merocrine gland
secretory products are stored in the cell near the lumen of the duct. A portion of the cell near the lumen containing secretory products is pinched off the cell and joins secretions produced by a merocine process.
Apocrine gland
Secretory products are stored in the cells of the gland. Entire cells are shed by the gland and become part of the secretion. The lost cells are replaced by other cells deeper in the gland.
Holocrine gland
Generally absent in tetrapods except in mammals
Lost survival value when skin became covered with cornified cells
Synthesis of mucus will dehydrate craniates that don’t have continuous access to water
Mucous Glands
Present when there are hairs and sebum is exuded into hair follicles
Sebaceous Glands
Present when there are hairs and sebum is exuded into hair follicles
Ceruminous glands
glands that assist in lubrication of conjunctiva of the eye
Meibomian glands
Sebaceous Glands of mammals
Meibomian glands
which is an inflamed swelling on the conjunctival surface of the lid is caused by ducts of the Meibomian glands being occluded
Chalazion
Other sebaceous glands open independent of hair:
Lips
Glans penis
Labia minora
Areola
Sudoriferous or Sweat Glands in Furry animals
feet of cat and mice, lips of rabbits and side of head of bats
Sudoriferous or Sweat Glands in pangolins, sirenians, cetaceans and echidnas
Absent
Sudoriferous or Sweat Glands in Hippopotamus
only on the ears
example of Sudoriferous or Sweat Glands
Ciliary glands is one example
Scent Glands
anal gland
tarsal gland
temporal gland
Compound alveolar glands that develop in both sexes along the milk line
Number and location (axillary, thoracic, abdominal and inguinal) is dependent on the animal species
Mammary Glands
hormone responsible for milk-let down
Oxytocin
hormone responsible for milk production
prolactin
Very thick - hair follicles, erector muscle, numerous glands, connective tissue, vascular tissue, nervous tissue
Dermis of mammals
examples of dermal bones
Dermal bones of armadillos
Antlers and giraffe horns
separates the dermis from underlying muscles in mammals
Superficial fascia
is a type of contour-shaping adipose tissue found in cetaceans to replace hair
Blubber
bony structure derived from intramembranous ossification forming components of the vertebrate skeleton, including much of the skull, jaws, gill covers, shoulder girdle, fin rays, and the shells of turtles and armadillos.
dermal bone or investing bone or membrane bone
