Anatomy Physiology and Clinical Implications of the Avian Integument Flashcards
(24 cards)
• How does the avian skin differ from that of mammals?
Much thinner, effectively glandless and contains feather follicles
• What are the three layers of the epidermis?
The basal (germinative) layer, intermediate layer, outer cornified layer
• What are the two layers of the dermis?
Superficial layer & deep layer (contains feather follicles and smooth muscle)
• What is podotheca?
The non-feathered areas of the legs and feet
• What are scales formed from?
Heavily keratinised epidermis separated by folds of less keratinised tissue
• What glands are present in avian skin?
Uropygial gland, glands of the ear canal, Pericloacal glands, (keratinocytes)
• What is the function of the uropygial gland?
Involved in maintaining feather condition and secretions spread by preening – waterproofing function, secretes pro-vitamin D, oil affects light absorption and feather colouring
• Why might keratinocytes be described as glands?
Developing dermal cells (keratinocytes) undergo metamorphosis from cuboidal or squamous nature, lose organelles, produce lipids and keratin and dehydrate and lyses – lipid production of keratinocytes makes the entire skin an oil-producing gland
• What are the four patagia of the wing?
Propatagium, postpatagium, metapatagium, alular patagium
• What is rhamphotheca?
Horny covering of the maxilla and mandible – forms the beak
• Why is the beak very sensitive to heat, cold, pressure and pain?
High number of mechanoreceptors (Herbst corpuscles)
• What is the cere?
Keratinised skin situated at the base of the upper beak – colour is influenced by diet and hormones
• What is the difference between pterylae & apteria?
Pterylae – areas that contain feather tracts, apteria – areas that do not have feather tracts
• What are the common terms used to describe portions of the feather?
Calamus (short, hollow, tubular, in the feather follicle), rachis (extension of the calamus above the skin), shaft (calamus & rachis) & vane or vexillum (the portion of the feather that extends to either side of the rachis)
• What does the quality of the bars and barbules of the feather give an indication of?
Nutritional status of the bird
• List some of the common types of feather
Contour feathers – predominant feather type
Convert feathers – small contour feathers of the wing and tail
Remiges feathers – large stiff feathers of the wing
Retrices feathers – large flight feathers of the tail
Specialised adapted feathers – semiplumes, hypopnea, filiplumes & bristles
Down feathers – adult, natal & powder down
• What are powder down feathers?
Specialised down feathers that disintegrate and produce keratin that is spread through the features during preening
• How does a feather follicle form?
Invagination of the skin, consists of epidermal and dermal cells, follicular wall has an abundant supply of sensory nerve fibres and the papillae, pulp and feather muscles are also well innervated
• Describe the process of moulting
Soft keratin structures undergo constant moult and replacement, feathers moult by the growth of a new feather causing the shedding of an old one
Moult can be gradual, dramatic or continual
• What hormonal influences have been identified as affecting the moult?
Oestrogens, progestogens, thyroid, catecholamines, prolactin
• What are the effects of inadequate nutrition on the moult?
Delays or interrupts the moult, reduces the rate of feather production, sustains production at the cost of other body functions
• What are stress lines?
Clear breaks in feather colour as a result of an interruption in feather growth and malformation of the feather barbs
• What is feather colour determined by?
Biochromes & structural properties
• What are the two basic types of colour mutations?
The genetic ability or inability to absorb, manufacture or deposit colour pigments & an alteration in feather structure creating a different reflecting or absorptive light pattern
