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The mammary gland likely evolved from a(n) _________; it is a ___________ gland.
apocrine sweat gland; compound tubuloalveolar
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Are there anatomical barriers b/w the quarters in a cow's mammary?
two distinct halves; no anatomical barriers b/w rear and front
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What is the secretory unit of the mammary gland?
alveoli (simple myoepithelial cell)
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Describe the components of the mammary from smallest to biggest?
lobule--> lobe--> quarter--> mammary
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Growth and development of the mammary gland.
mammogenesis
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Establishment of milk secretion.
lactogenesis
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Maintenance of milk secretion.
galactopoiesis
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Return to non-lactating state.
Involution
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The mammary gland is derived from __(2)__ of the developing embryo.
ectoderm and mesoderm
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Describe the mammary structure and function in a newborn heifer. (5)
teat are developed, blood and lymph formed, mostly fat tissue, no secretory or glandular structures developed
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Describe fetal development of the mammary gland.
mammary bands--> mammary buds--> primary sprout--> secondary sprout--> canalization
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The first 2-3 months after birth, there is _________ growth of the mammary gland; there is no _________ development.
isometric; secretory alveoli
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After 2-3 months of age, there is __________ growth of the mammary; there is no _________ development, but there is elongation of the ___________.
allometric; alveoli; ductal network in stromal tissue
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At approximately 12 months of age, growth of the mammary transitions to ________ growth; there is _________ development.
isometric; alveoli
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What hormones are required for normal mammogenesis? (4)
estradiol, progesterone [ovarian steroids]; growth hormone [pituitary hormones], placental lactogen [fetal placental hormone]
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What is the role of estradiol in mammogenesis?
induces ductal growth and epithelial cells [secretion of growth factors from stromal cells]
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What role does progesterone play in mammogenesis?
stimulation of ductal side branching and formation of alveolar buds
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Estradiol stimulates ________ receptors at the mammary gland.
progesterone
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What role does growth hormone play in mammogenesis?
stimulates glandular growth during all stages of development; stimulates IGF-1
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What role does placental lactogen play in mammogenesis?
synergizes with estradiol, progesterone, prolactin, and GH
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How does parturiation affect the hormones involves with lactation?
increases prolactin, glucocorticoids, GH, and estradiol; decreases the negative influence of progesterone (in the cow to allow her to begin lactating)
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Simultaneous increase in __(2)__ concs are required for final mammary growth.
estradiol and progesterone
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The removal of __________ at parturition initiates lactation.
progesterone
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There are no ________ receptors in the mature mammary gland; therefore, after lactation has been initiated, administration of ________ had no effect on milk yield.
progesterone; exogenous progesterone
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Hormone responsible for the onset and establishment of lactation; receptors are increased in the mammary near parturition.
Prolactin
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Prolactin has a key role in ___________ but a lesser role in ___________.
lactogenesis; galactopoiesis
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What are the effects of a reduced basal prolactin?
reduced milk production
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What role do glucocorticoids play in lactogenesis and galactopoiesis? (2)
differentiation of alveolar secretory cells during lactogenesis; support homeostasis
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Lactating cows double the amount of _________ in the mammary cells when compared to non-lactating cows.
glucocorticoid receptors
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What role does oxytocin play in lactogenesis and galactopoiesis? (2)
milk let down, milk production throughout lactation
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What role does insulin play in lactogenesis and galactopoiesis? (1)
nutrient utilization
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What role do the thyroid hormones play in lactogenesis and galactopoiesis? (2)
maintenance of lactation, support homeostasis
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What role does GH play in lactogenesis and galactopoiesis? (2)
galactopoietic hormone, promotes flux of nutrients and energy in mammary
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How does BST administration increase milk secretion? (2)
directly and indirectly stimulates mammary tissue, effects other tissues to supply nutrients to support milk production
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What effects do lactogenesis and galactopoiesis have in body tissues? (2)
decrease glucose uptake, decrease oxidation of AAs for energy
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What effects do lactogenesis and galactopoiesis have in the liver? (1)
increased gluconeogenesis
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What effects do lactogenesis and galactopoiesis have in fat stores? (4)
decreased uptake of glucose, decreased lipogenesis, increase lipolysis, increased glucose from glycerol via lipolysis
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Why is it essential to remove milk a frequent intervals? (4)
reduce intramammary pressure, increase blood flow, removes substances that inhibit milk production--> increased milk production
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How long should the dry period be?
40-60 days
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What is a consequence of extended dry periods?
>80 days has a negative effect on future milk production
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During mammary gland involution, there is _________.
apoptosis
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What histological changes associated with mammary gland involution? (4)
increased leukocytes and connective tissue, decreased intra-alveolar area and cytoplasmic organelles
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Raw materials for milk production are obtained from ________.
blood
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5 mechanisms of secretion of milk contents.
milk fat pathway, golgi pathway, transcytosis, transporter channels, paracellular transport
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Release of oxytocin from the _______ causes __________ [at the cellular level].
posterior pituitary; contraction of mammary myoepithelial cells
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A mixture of lacteal secretions and blood serum constituents, that is accumulated in the mammary gland during the last weeks of pregnancy, and that is crucial for the transfer of passive immunity to the newborn.
colostrum
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Pre-partum transfer of Ig from maternal circulation into mammary gland secretion.
colostrogenesis
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Colostrogenesis begins ___________ and stops __________.
4-6 weeks before parturition; abruptly after calving
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Colostrogenesis is influenced by what hormones? (3)
estrogen, progesterone, prolactin
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What are the 2 classes of mastitis pathogens?
contagious and environmental
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What are the 3 most important contagious mastitis pathogens?
Strep ag, Staph aureus, Mycoplasma
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What are the most important/common environmental mastitis pathogens? (8)
E. coli, Klebsiella, environmental Strep, Coag-neg Staph, Corneybacterium, Enterobacter, Proteus, Pseudomonas/Serratia
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Pathogens that typically do not infect the mammary gland but can do so with contamination; they are less adapted for survival in the udder.
environmental mastitis pathogens
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Pathogens that originate in the udder that colonize the mammary gland; often cause subclinical infection and have long/chronic duration.
contagious mastitis pathogens
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Contagious mastitis pathogens are generally gram _______.
positive
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Describe Grade 1 mastitis. (3)
flakes in the milk in 1 or more quarters, no visible inflammation, decrease in milk yield
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Describe Grade 2 mastitis. (4)
abnormal milk in 1 or more quarters, visible udder inflammation, +/- pain/fever, decreased milk yield,
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Describe Grade 3 mastitis. (6)
abnormal milk in 1 or more quarters, visible udder inflammation, pain, change in udder coloration, +/- fever, decreased milk yield
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Grade 3 mastitis is associated with _________.
coliform bacteria--> systemic infection/septicemia
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Describe treatment of mastitis. (7)
dump milk, intramammary antibiotic, systemic antibiotic (if coliform), increase milking frequency, oxytocin, banamine, dehydration/drench
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