2. skin glands Flashcards
what are the 2 basic types + subtypes of skin glands?
- sebaceous
- sweat glands: eccrine + apocrine
what are skin glands modifications of?
Modifications of the epidermis, even though they penetrate into the dermis
what are skin glands modifications of?
Modifications of the epidermis, even though they penetrate into the dermis
what are skin glands modifications of?
modifications of the dermis even though they penetrate into the dermis
what are sebaceous glands and what do they produce?
They are glands associated with hair follicles that have many lobes (acinar structure). They produce sebum which is fatty and oily
What is sebum called in sheep?
lanolin
what are the main 4 functions of sebum?
- waterproof hair and skin
- allows sweat to spread
- antimicrobial function
- pheromones and other scented compounds for communication
Name the 10 sebaceous glands and the main species they are found in
- Circumoral: cats
- Cirucumanal : dogs
- Carpal : cats and pigs
- Tail : cats and dogs
- Anal sac: cats and dogs
- Horn: goats
- Glands of infraorbital pouch: sheep
- Glands of interdigital pouch: sheep
- glands of inguinal pouch: sheep
- Preputial glands : boar
What are the two sweat glands and the differences between them?
- Apocrine discharge albuminous (protein-rich) while eccrine is watery
- Apocrine sweat is released into hair follicles while eccrine is released directly onto the skin
- apocrine glands are found over most of the body (haired skin) in domestic animals while eccrine are generally found only in certain areas (naked skin) e.g footpads
what do apocrine sweat glands secrete and how?
apocrine secretion
vesicles pinch off from cells to secrete packets of cell membrane and cytoplasm
what do eccrine sweat glands produce and how?
merocrine secretion
- exocytosis
- cell vesicles fuses with membrane to discharge its contents
- no part of the cell is lost
what are mammary glands and what are their functions?
they are extremely modified apocrine sweat glands
- the secretion (milk) is rich in protein and fat for nourishing the young
- contains antibodies for immune transfer
- first milk (colostrum) os rich in antibodies especially
what is the structure of a mammary gland?
- mammae body and teat
- collections of mammary glands called udders in ruminants and horses
each gland contains 1+ secretory units
sometimes extra buds develop into supernumerary teats
How many teats do these animals have?
- sow
- dog
- cat
- cow
- sheep
- horses
- sow: 14
- dog: 10
- cat: 8
- cow: 4
- sheep: 2
- horses: 2
how is milk made in the mammary glands?
- milk is produced by mammary cuboidal epithelial cells lining the alveoli
- alveoli are surrounded by muscle cells (myoepithelial cells) that push the milk out of the alveolus
- milk drains through milk ducts (lobular ducts -> lactiferous ducts)
- Milk is stored in the lactiferous sinus
- smooth muscle sphincter at teat or orifice
- milk is let dow under influence of hormones
what does the smooth muscle sphincter at the teat orifice do?
prevents milk leakage and bacterial entry
what happens in the gland/teat for milk to be let down?
- Contraction of myoepithelial cells around alveoli
- relaxation of the teat sphincter muscle
The transition between gland sinus and tea sinus is marked by what?
mucosal fold
do milk ducts cross over in cows? explain
no, there is 4 quarters with no cross over
what supports the mammary gland in cows?
- median suspensory ligament (more elastic)
- lateral suspensory ligament (more fibrous)
when are mammary glands fully developed?
height of lactation
Do birds have sweat glands?
no
How do birds lose heat if they have no sweat glands?
- Skin: blood flow
- respiratory evaporation
what deposits a lipid film onto feathers?
lipogenic epidermis
what 3 sebaceous glands do birds have?
- uropygial gland (preen)
- aural gland
- vent gland
what main skin glands do reptiles have?
- scent glands: most lizards and snakes
- pre-femoral/femoral glands: in many lizards
what does the preen gland produce in birds and what is its functions?
produces an oily secretion
- waterproofing
- feather care
- antimicrobial + antiparasite function
- vitamin D precursor: produces vit D from sunlight to create active vit D
what skin glands do ferrets have?
- widely distributed sebaceous glands
- anal glands
- no sweat glands
what are the skin glands in guinea pigs?
- numerous sebaceous glands
- caudal gland
what skin glands o hamsters and gerbils have?
- flank scent glands (Syrian hamsters)
- ventral glands (dwarf hamsters + gerbils)
what skin glands do rabbits have?
- chin gland
- inguinal gland
- anal gland
what glands do fish have + the functions?
mucus glands
- insulation
- protection
- reduce water friction
venom secretion
