mammary physiology quiz 3 Flashcards
subclinical mastitis symptoms
- milk udders appear normal
- milk contains high SCC
- infections are long, sometimes with bouts of clinical symptoms
clinical mastitis symptoms
- visual abnormalities in milk
- ## short term infections
Effects and treatment of gram negative bacteria
- LPS of cell wall is released along with endotoxins after bacterial death
- not treatable with antibiotics
- more of these cases become clinical
Effects and treatment of gram positive bacteria
- contain lipotechoic acid, typically are host adapted
- longer duration infections
- most remain in subclinical state
what two pathogens affect the milk, ducts, and parenchyma
strep spp. and S. aureus
what three pathogens affect the milk and ducts?
coryne, s. agalactiae, staph spp.
what pathogen affects the cow?
mycoplasma
what pathogen affects the milk, ducts and cow?
coliforms
what type of resistance occurs at a genus/species leve and involves the target organism lacking a binding site?
intrinsic resistance
what type of resistance involves a previously susceptible strain of bacteria that becomes resistant due to a mutation or DNA acquisition and causes the potential spread to humans?
acquired resistance
what are the three D’s to guide antibiotic therapy decisions
Detect (when was the cow infected?does this require immediate treatment?); Diagnose (is active bacteria still present?); Decision (will antibiotics help this cow?
inflammation persist in milk for ______ days with or without a biological cure
3-5
antibiotics are rarely useful for cows with previous diagnosis of _________, > or = 3 previous treatments for ____, >4 months of SCC> ________ cells/mL, and chronic clinical or subclinical mastitis in previous lactations
refractory pathogen; CM; 200,000
what are the 5 non-antibiotic treatment options?
- watchful waiting
- dry off affected gland
- divert cow to beef market
- segregate cow and use 1/4 milker
- early dry off of cow
Which of the following would most reduce persistency?
a. Fostering a newborn on another dam
b. Missing one milking in a dairy herd milked 3 times per day
c. Late pregnancy (7 months) in a dairy cow
d. Providing a dry or nonlactating period between lactations
e. All of the above would be equivalent
c. Late pregnancy (7 months) in a dairy cow
Increased frequency of milking or suckling
a. Reduces metabolic activity of mammary epithelial cells
b. Stimulates daily milk yield
c. Stimulates mammary epithelial cell loss
d. Stimulates the involutionary process
e. All of the above
b. Stimulates daily milk yield
Exogenous growth hormone would increase milk yield in cows only if
a. given during the first lactation of a dairy cow’s life
b. a dairy cow is in “positive energy balance”, or has sufficient nutrients available to support increased milk production
c. given during the first week of a cow’s lactation
d. it was given as an oral protein in her feed
b. a dairy cow is in “positive energy balance”, or has sufficient nutrients available to support increased milk production
Milk yield is equal in two cows through day 30 of lactation. Beginning on day 31, cow A is injected daily with a high dose of cortisol and cow B is not treated. One week later….
a. Compared to cow B, milk yield would decrease in cow A
b. Compared to cow B, milk yield would increase in cow A
c. Relative to cow B, milk yield would be unaffected in cow A
d. Relative to cow B, endogenous secretion of cortisol would most likely be decreased in cow A
e. More than one answer is correct
e. More than one answer is correct
Exogenous estrogen administration has been shown to
a. reduce milk yield in a variety of species
b. inhibit lactation by disrupting myoepithelial cell function
c. affect milk production regardless of whether progesterone is also administered
d. all of the above
d. all of the above
Proven strategies for evaluating milk yield in various species include
a. weigh-suckle-weigh
b. litter growth index
c. measurement of total RNA in mammary parenchyma
d. all of the above
d. all of the above
In cattle, shortly before milking, most milk is stored where?
within the lumen of the alveoli
stimulation of the milk ejection process involves release of a hormone from the…
posterior pituitary gland
when is intramammary pressure the greatest?
during the initial phase of milking
oxytocin is synthesized in ribosomes of the
a. Herring bodies
b. Neurophysins
c. Paraventricular nucleus of the hypothalamus
d. Posterior lobe of the posterior pituitary
e. Supraoptic nucleus of the hypothalamus
f. More than one answer but not all are correct
f. More than one answer but not all are correct
Efficient milk ejection relies on
a. contraction of myoepithelial cells following cortisol binding
b. interaction of offspring and mother
c. normal blood flow to the gland
d. estrogen priming of receptors
e. more than one but not all of the above are correct
e. more than one but not all of the above are correct
Milk ejection
a. can be initiated by a single piglet in between regular bouts of nursing by the rest of the litter
b. occurs at regular intervals that differ by species
c. always occurs within the half-life of oxytocin (1 minute) following beginning of stimulation of the teat
d. none of the above
b. occurs at regular intervals that differ by species
Mastitis affects the mammary gland and body by what two modes?
- causing epithelial cell apoptosis and decreasing their activity
- elevating number of leukocytes
what organism cases clinical mastitis most often?
coliforms
factors influencing the risk for acquiring mastitis include: (4)
- environmental cleanliness
- exposure to bacteria
- health of animal
- virulence of pathogen
why is mastitis risk higher at the time of dry-off? give two reasons
- intramammary pressure increasees with the end of milk removal
- milking helps flush out bacteria from teat
apoptosis describes the process whereby ________ during ________
epithelial cells die; involution
Milk synthesis depends on intracellular milk synthesis in the ___________, as well as the passage of milk from the __________ into the ________
alveolar epithelium; cytoplasm; alveolar lumen
galactopoieses is the…
maintenance of milk secretion
what factors cause active vs. passive milk withdrawal
- active: oxytocin stimulation
- passive: suckling
maintaining lactation requires the maintenance of what three factors?
- number of mammary cells
- cellular synthetic activity
- milk ejection efficiency
persistency is…
the degree to which milk yield is maintained; function of mammary cell number
when insulin is elevated, nutrients are partitioned more toward _____ and not ____
body tissues; milk
estradiol inhibits lactation in women by
disrupting myofibrils in myoepithelial cells
the inhibition of milk secretion that accompanies increasing intra-mammary pressure is probably caused by a chemical inhibitor called the
Feedback inhibitor of Lactation (FIL)
nerve transmissions - afferent _____, efferent _____
arrives, exits
increasing milking frequency ______ intramammary pressure and _______ milk yield
decreases; increases
oxytocin is synthesized in the _________ and _______ of the hypothalamus
PVN (paraventricular nucleus); SON (supraoptic nucleus)
There are two ways milk ejection is inhibited. ______ involves decreased oxytocin release from the posterior pituitary gland; _____ involves decreased oxytocin at the mammary gland mediated by release of epinephrine and norepinephrine from the adrenal glands
central inhibition; peripheral inhibition
name the four stages of milk ejection
massage phase, non-nutritive sucking phase, nutritive phase, post-massage phase
______ may initiate an irreversible involution of mammary epithelium in that lactation
delay in milk removal
mammary epithelium is increasingly sensitive to ____ with advancing lactation
oxytocin
involution - changes in epithelial cells
- decrease in metabolic activity, alveolar size/shape, and volume/number of alveoli
- increased visibility of connective tissue
- cessation of milking -> increased intra-alveolar pressure -> increased presence of lysosomes -> more phagoctyosis
- secretions contain more immune cells and lactoferrin
- by the end of involution, gland resembles that of a virgin animal
remodeling/involution occurs in what three phases?
active involution, steady state, mammogenesis/re-development
changes in alveolar fluid compounds
- concentrations of lactose, casein, and milk fat decline
- lactoferrin increases
- immunoglobulins and serum albumin increase
continuously milked cells _____ turnover of cells
decreases
