avian integument Flashcards
what is the difference between bird skin and mammalian skin
- much thinner, glandless and contains feather follicles
- epidermis consists of basal layer, intermediate layer and outer cornified layer
- striated muscles in the epidemris move the skin
what are the division of the avian dermis and what do they each contain
- superficial layer containing loosely arranged layers of collagen in interwoven bundles
- deep layer containing fat, feather follicles, smooth muscles that control the movement of feathers, blood vessels and nerves that supply the dermis and epidermis
describe the subcutaneous layer of the avian integumentq
- formed mainly by loose connective tissue\
- contains fat as a layer and discrete fat bodies (appear as yellow deposits beneath the skin, commonly lateral to pectoral muscles, in cloacal region and on the back but varies species to species)
discuss how the skin of the legs and feet in avians is unique
- the non feathered areas of the leg and feet contain scales formed from raised heavily keratinised epidermis separated by folds of less keratinized tissue
avian skin is effectively glandless. name execptions
- uropygial gland
- glands of the ear canal
- pericloacal glands
- keratinocytes
what is the functuion of the uropygial gland and discuss how it works
- involved in maintinaing feather condition and secretions spread by preening
- serves waterproofing function
- holocrine gland
- secretions contain pro-vitamin D converted by UV light to active vitamin D
- oil affects light absorption and feather colouring
- secretions are believed to suppress the growth of micro-organisms
discus how the keratinocytes of birds are different from those of mammals
- developing dermal cells (keratinocytes) undergo metamorphasis from cuboidal or squamous nature, lose organelles, produce lipids and fibrous proteins (keratin) and dehydrate and lyse
- this function is unique to birds and it is suggested that the lipid production by the keratinicytes makes the entire skin and oil producing gland
what is patagia
skin may be reflected into flat, membrane like structures in areas where the wings, legs, neck and tail join the body. these tend to be areas where movement of limbs occurs
on the wings it is responsible for wing stability and aiding in aerodynamics
what are the names of the 4 patagia on the wing
- propatagium: wing web junction of the neck and wing
- postpatagium: formed at the caudal angle of the carpi
- metapatagium: caudal junction of the wing and the thorax
- alular patagium: interspace between the alula and the carpi
discuss the integument of the beak
- horny covering over bone called rhamphotheca
- similar to the skin with modified epidermis but stratum corneum is very thick and contains cell bound calcium phosphate and layered crystals of hydroxypatite
- high number of mechanoreceptors (beak sensitive to temp, pressure, pain)
- egg tooth only in recently hatched neonates (keratin eminance on dorsal surface of upper beak)
- Cere situated at the base of upper beak, made of keratinised skin. where nostrils often located
name functions of the feather
- flight
- insulation
- waterproofing
- courtship display
- defence
- aggressive territorial behaviour
what are the areas contiaining feather tracks called? areas not containing feather tracks?
- pterylae = contain feather tracks
- apteria = no feather tracts (best to visualise underlying skin)
what is the calamus
the short, hollow, tubular, unpigmented end of the mature feather inserted into the feather follicle and thus present below the level of the skin
what is the rachis
the long, solid, tubular extension of the calamus above the skin, the rachis contains pith which is composed of air filled keratinized epithelial cells surrounded by a solid keratinized outer cortex
what is the shaft of a feather
made up of the calamus and the rachis
what is the vane or vexillum
the portion of the feather that extends either side of the rachis and is composed of the barbs and their associated structures. the vane is either plumulaceous (soft/downy) or pennaceous (compact and closely knit) depending on the individual type of feather
