Physio 2 - Repro 3

drraythe's version from 2015-06-09 01:46

repro cycles continued

Question Answer
what repro stuff happens with FERRETS with ADRENAL DZ? (symptoms, and what they stem from)they get excess sex steroids, but cortisol/aldosterone normal. Estrogens>androgens--> alopecia, enlarged vulva, prostate hypertrophy, sexual aggression, marrow DEPRESSION. (from too many estrogens)
optimal timing of mating with ovulation is when?mate 12-24hrs before ovulating
the hypothalamic (b/h) sex center stim by what?high levels of estrogen (estrus phase)
explain "silent heat" (include who this happens in)hypothalamic (b/h) sex center requires priming by low levels of progesterone (cattle,pigs, sheep)--> first cycle after anestrus does NOT induce estrus b/h. (first cycle after parturition, first cycle of breeding season)
what are pheromones, produced by what, what can they do?volatile/non-vol. chemicals produced by genitals/urinary tissue/sebaceous glands as olfactory communicators to influence estrous cycle and mating b/h
What is the whitten effect?INDUCITON of CYCLING in females after introduction of males to the herd--> used to synchronize females and advance breeding season (sheep, goat) (girls gotta use their wit around a guy)
what is the Vandenbergh effect?gilts reach puberty earlier when exposed to a boar--> used to advance ONSET of puberty in pigs.
if you wanted to breed a flock of sheep during their first cycle of the season when they are usually in silent heat (no estrus b/h b/c no progest. priming) what would you do?Silent heat can be stopped by giving progesterone to the animal before their first cycle (and before introducing males),Used so that entire herd will be centralized and to advance the breeding season

Gestation and parturition

Question Answer
what is imperative for the establishment of pregnancy and maintenance of corpus luteum?PROGESTERONE!!! (so luteolysis must be avoided, b/c CL is making the progesterone)
what would happen if animal preg and progesterone drops?endo. would undergo regression--> interrupt nutrient supply and beginning attachment process between conceptus+endomet= ABORTION
before conceptus attaches (2-4 weeks AFTER ovulation) how does it prevent itself from being aborted?conceptus produces signals to maintain CL, therefore progesterone production. It does this by inerfereing with endometrial PGF2alpha release
most important hormone to maintain preg? where is it produced?PROGESTERONE. first in the CL, then later in preg the placenta contributes or takes over the production.
what three things does progesterone do during preg?(1) maintain secretory activity/perfusion of endometrium. (2) dec uterus tone and inc cervix tone= PROGESTERONE BLOCK. (3) prepares mammary gland during late preg.
what is the MOST IMPORTANT event initiating parturition?inc in FETAL CORTISOL production, which leads to progesterone withdrawl (b/c it stims placenta enzymes to convert proges into estrogen)
what sends the initial signal to end gestation? how? Saftey measures to make sure this doesnt happen too early?FETUS gives of massive CORTISOL release. the fetus makes the CRH+ACTH during mid/end gestation (maybe stress b/c space limitations). also the adrenal cortex matures late (prevent from happening sooner, genetically controlled) so fetal cortisol release occurs only during last few days of gestation. no neg feedback cortisol-->ACTH
the fetal cortisol goes WHERE first?PLACENTA.
how does the cortisol affect the placenta?stims 2 steroid hormone enzymes to convert PROGESTERONE into ESTROGEN! inc estro and dec proges= removal of progesterone block
once the cortisol has caused placenta to convert proges into estrogen, and estrogen is inc, what effects does estrogen have? (3, general)(1) prepares myometrium to become contractile (2) inc lubrication (3) stim synth of placental PGF2alpha/ E2(estrogen)
how does estrogen specifically affect the myometrium?the # gap junctions and the myometrium INC--> single unit type sm. mm to facilitate coordination of contractions. also stim synth of of contractile proteins (Actomyosin) and inc in oxytocin receptors (PREPARES MYO. TO BECOME CONTRACTILE)
how does estrogen effect lubrication?sim mucus secretions of cervix to lubricate birth canal
what are the effects of PGF2alpha and E2 (estrogen) during parturition? (4)(1) initiates regression of CL (withdrawl progesterone) (2) relax/dilate cervix (3) inc intracellular Ca++/myometrium (initiate CONTRACTIONS) (4) in SOME species, the CL produces the hormone RELAXIN (which inc markedly with PGF2alpha induced final luteolysis apprx 10-14 hrs prior to birth. other species, gradual relaxin inc during last weeks of gestation)
what are the effects of relaxin? (2)(1) relax pelvic ligs and mm (2) separation of pelvic symphysis ---> both facilitate expansion of the birth canal
what is involved in stage one of parturition?initial myometrial contractions induced by PGF2alpha push fetus slowly towards the internal os of the cervix. in LG SPECIES, fetus turns from its ventral to a dorsal position.
what is the delivery position/what is it called in large species?"diving position" which is an anterior presentation (back is dorsal, head is caudal, forelimbs foreward)
what is the delivery position in small species?fetus presents in either anterior or posterior postion while being pushed slowly towards the cervix
what is stage two of parturition?as fetal membranes/legs/head/butt push against/enter cervix, pressure receptors stim and initiate FERGUSSON REFLEX/OXYTOCIN RELEASE which initiates rhythmic myometrial contractions (and abdominal mm too)==> EXPULSION OF FETUS
what is stage three of parturition?delivery of FETAL MEMBRANES through sustained surges of PGF2alpha (from placenta).
when are the fetal membranes delivered in species that litter bear? single bear?litter= with or after each fetus. single= up to several hours after fetus.
what is PUERPERIUM? what happens during it?period of uterus involution and regeneration (6 days-weeks). attachment points of fetal membranes slough off, new epithelium forms= healing of endometrum. myometrium contracts= size reduction.
what hormone is released during the last days BEFORE parturition? what does it do?PROLACTIN, it induces lactogenesis and induces maternal b/h.
what is the order of hormones for parturition?CEPRO! Cortisol--> estrogen--> PGF2alpha--> relaxin--> oxytocin.


Question Answer
what is the alveolus? explain its structurethe milk secreting unit, it is lines w/a single layer of epi. cells and surrounded by a dense capillary network and myoepithelial cells
describe the mammary gland from birth->before puberypresent, rudimentary duct system, parynchema consists of adipocytes and fibroblasts, growth proportional to body growth.
describe the mammary gland during sexual maturity (What two things to what during pubery to cause this)bigger, more mature. exponential growth during first estrus cycles Estrogen--> lengthening and branching of ducts. Progesterone--> lobulo-alveolar development
describe the mammary gland during pregnancy, why is it this way?gland becomes functional DURING GESTATION, stroma is replaced with alveolar tissue b/o long-standing high ESTROGEN/PROGESTERONE levels.
when does the actual production of milk occur? (name for this)(lactogenesis) only a few days before parturition
what does estrogen do to the mammary gland during puberty? what does progesterone do?estrogen=lengthen/branch ducts. progesterone=lobulo-alveolar development
what are the two phases of lactogenesis?INDUCTION (before birth) and MAINTENANCE (post parturition)
what is the induction phase of lactogenesis coordinated with?coordinated with parturition, milk production actually starts a few days BEFORE this, and the secretions accumulate in the mammary gland (=colostrum).
how is the induction phase of lactogenesis induced? (3)(1) withdrawl of progesterone prior to birth (2) inc in cortisol to induce prolactin receptors (3) inc in PROLACTIN a few days before birth, sitm by prolactin RH and suppression of prolactin IH= DOPAMINE.
what is colostrum? what are the contents/ solute conc of these?milk produced during induction phase (w/o removal). solute conc are 2-3 times that of normal milk (except lactose), with an Ig conc of 30-40xs that of normal milk
what does colostrum provide? (5)(1) passive immunity to newborn (GI mucosa attachement and absorption of Ig's-- needs to be in first 6-24hrs before GI closes) (2) conc nutrients (3) growth factors (eg somatomedins) and immune system factors (4) laxative (5) casomorphins
what is "group 1" of colostrum animals refer to?placenta epitheliochorialis- no Ig xfer in utero= COLOSTRUM-DEPENDENT
what is "group 2" of colostrum animals refer to?placenta endotheliochorialis- Ig xfer in utero + via colostrum
what is "group 3" of colostrum animals refer to?placenta heochorialis- Ig xfer sufficient in utero
maintenance phase- what is continuous milk secretion dependent on?on regular milk removal, which leads to release of prolactin
when is prolactin released during lactogenesis (maintainance)during suckling. tactile stim--> SC--> hypothalamus--> VIP (vasoactive intestinal peptide) release a/o dopamine (=PIH) inhibition- ant. pituitary secrete prolactin into circulation--> mammary prolactin receptors--> LACTOGENESIS
what inhibits lactation in most species?dopamine
what animal DOESNT use prolactin? what do they use instead?RuMINANTS use GROWTH HORMONE (=somatotropin) instead
how does milk let-down (ejection) occur?neuro-endocrine reflex-- touch and heat receptors/teats--> sensory nerves--> hypothalamus--> post. pit.--> OXYTOCIN release--> circulation--> contraction of myoepi cells--> milk letdown within 1 min after stim
what happens if there is no milk removal?pressure inc, which ceases milk production (regular removal essential for continued milk production)
how do some diary farms increase yield?oxytocin injections prior to milking (makes myoepi cells contract more)
lactation increases for how long? then gradually declines until the end, around __days (cows)3-4 weeks there is an inc, ends at ~305 days
what happens to the mother during the first few weeks of lactation?in a neg energy balance, will lose body condition.
what is the danger of using bovine growth hormone/somatotropin (bST) to get more milk?it inc production at the expense of body reserves, mobilizes the body stores, worsens the neg energy balance situation, and can put the cow in danger of hepatic lipidosis/ketoacidosis
cessation of milking/suckling at time of weening induces what?involution of alveolar tissue
what three things happen during involution?(1) alv. cells lysed by lysosomal enzymes (2) alv cells replaced by adipocytes (3) myoepi cells remain
what happens if the dry period is too short?alv cells are carried over to the next lactation, but have REDUCED SECRETORY CAPACITY! so reduced milk yield.
what is the minimum dry period for diary cattle?6 weeks

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