CA Epidermal derivatives
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What are the epidermal derivatives?
- 1. Beaks
- 2. Epidermal scales
- 3. feathers
- 4. Hair
- 5. Claws, nails, hooves
- 6. Horns
What are beaks?
Beaks are tickened epidermis covering the jaws.
What are epidermal scales?
Embryological outpushing of epidermis containing a small papilla of mesodermal tissue, connected by narrow zones of uncornified epidermis.
What do feathers derive?
they derive from the stratum corneum.
Feathers do not cover the body, but lie in tracts called _____; featherless areas are _____.
What are the different types of feathers?
- 1. Down (Plumules)
- 2. Filoplumes
- 3. Contour feathers ( flight feathers)
Contour feathers (Flight feathers) are divided into two catagories called_______ and _______.
- 1. Remiges (Wings)
- 2. Retrices (Tail)
What are the components of contour feathers?
- 1. Quill
- 2. Shaft (Rachis)
- 3. Aftershaft
- 4. Barb
- 5. Barbule
- 6. Follicle
- 7. Vane
What is the function of the quill?
Inserts into the skin.
What is the function of the shaft (Rachis)?
Main support beam for feather.
What is the function of the aftershaft?
a small secondary feather located near the plume base of some feathers.
What are the function of barbs?
they are small lines that extend from the shaft to make the cane of the feather.
What is the function of the barbule?
smaller hook-like offshoot from the barb that holds barbs together.
What is the function of the follicle?
the area in the skin from which the feather grows.
What is the function of the vane?
the collection of barbs that provide a wind resistant surface for flight.
______ is strictly mammalian, purley epidermal in origin.
What is lanugo?
A downy coat of hair on a fetus, lost just before or just after birth.
What are the parts of the hair?
- 1. Shaft
- 2. Root
- 3. Hair follicle
- 4. Bulb
- 5. Dermal papilla
Where is the shaft of hair located?
above the skin
Where is the root of hair located?
Where is the hair follicle located?
pit sunk in dermis.
Where is the bulb located?
is is a hollow structure surrounding dermal papilla.
What is the dermal papilla?
it contains connective tissue, blood vessels.
What are the structures indicated by the cross section of a hair?
- 1. Cuticle
- 2. Cortex
- 3. Medulla
What is the cuticle?
outside, it is a pattern of scales.
What is the cortex?
it is a layer inside the cuticle.
What is the medulla?
it is the inner layer, pigment is usually found there.
What are claws, nails, and hoves?
They are highly keratinized structures at tips of digits in amniotes.
The _____ is the harder upper portion of a nail of claw.
_______ is the softer under portion of nail of claw.
What animal contains a true horn and what are the characteristics?
- These never shed, made of a bony core and dpidermal sheath.
What animal contains a pronghorn and what are the characteristics?
- a true horn whose bony core is never shead, but the epidermal sheath is shed.
What are the characteristics of giraffe horn?
bony core is covered by living skin.
What animals contain antlers and what are the characteristics?
- bony core grows anew each year, velvet is the skin.
What animal contains a rhinohorn and what are the characteristics?
- agglutinated hair-like filaments, always grow, never shed.
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