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159 Cards in this Set
- Front
- Back
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What are the functions of the male reproductive system? |
- produce sperm - ensure sperm maturation - ensure sperm deposition in the female reproductive tract for the sexual production of offspring |
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What is produced in the testes? |
- sperm - steroid hormones |
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What are the functional components of the male reproductive system? |
- penis - testes - scrotum - epididymis - vas deferens - male accessory organs
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What are the male accessory glands? |
- ampullae - Prostate - Seminal vesicles (or vesicular glands) - bulbo urethral gands |
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Which species lacks seminal vesicles/ vesicular glands and bulbourethral glands? |
canine (only accessory glands it has are ampullae and prostate) |
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What is responsible for the large volume of semen produced by boars? |
very large seminal vesicles and bulbourethral glands |
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Which species has the largest testicles in proportion to body weight? |
technically the golden hamster but within the domestic species it is the pig |
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Describe the anatomy of the testicular parenchyma |
Seminiferous tubules make up the larges component - within the tubules the parenchyma is separated into basal and adluminal components - outside the tubules the parenchyma is vascular and interstitial |
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What are mechanisms employed to maintain proper testicular temperature? |
- numerous sweat glands on testes - contraction/relaxation of the cremator muscle - pampiniform plexus |
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Describe the role the cremaster muscle plays in maintaining testicular temperature |
- when it is cold outside the muscle contracts to pull the testes closer to the body for warmth - when it is warm outside the muscle relaxes allowing the testes to fall further from the body |
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Describe the role of the pampiniform plexus in maintenance of testicular temperature |
The pampiniform plexus is a vascular network composed of the testicular artery surrounded by a convoluted testicular vein the arrangement of these two structures allows heat to pass from the artery to the vein as blood moves to the testes so that it is not too warm when it supplies this sensitive area |
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What creates the blood testes barrier? What is its importance? |
created by tight junctions between sertoli cells separating the seminiferous epithelium into apical and basal compartments - this prevents blood from directly reaching the apical compartment where sperm are made - because sperm are haploid they would be recognized as foreign by lymphoid cells and destroyed if they were not protected in some way |
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Describe Leydig cells: what is their function, where are they located, how are they controlled? |
- function: produce testosterone - location: interstitial tissue - control: stimulated by LH, inhibited by negative feedback of testosterone on hypothalamus and pituitary secretion of GnRH and LH |
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Describe Sertoli cells: What is their function, where are they located, how are they controlled? |
- function: convert testosterone for Leydig cells to estrogens and dihyrodrotestosterone, support spermatogenesis, produce inhibin and activin - location: seminiferous tubules - control: stimulated by FSH, inhibited by the action of inhibin on the anterior pituitary to suppresses FSH release, activin stimulates the release of more FSH enhancing stimulation |
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What is the function of testosterone in the male? |
- initiation and maintenance of spermatogenesis - development of secretory activity of accessory glands - development of secondary sex characteristics |
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Define puberty in the male and the female |
male: initiation of the ability to release mature germ cells female: the first estrus with ovulation, followed by CL formation and function of normal duration |
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What is the gonadostat hypothesis? |
theory used to explain the onset of puberty - applies to both males and females - prior to puberty the hypothalamus is most sensitive to negative feedback from steroidal hormones but as puberty approaches these receptors decrease and it begins to respond with positive feedback leading to increases in release of gonadotropins |
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Describe how seasonal breeding is controlled by photoperiod |
the retina detects light and triggers the release of melatonin from the pineal gland. Depending on the species this melatonin will either trigger or inhibit the release of GnRH from the hypothalamus leading to estrous cycle and spermatogenesis or suppression of these processes |
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What are some species that are seasonal breeders |
horses- breed during long photoperiods sheep - breed during short photoperiods |
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What are pheromones? |
chemicals usually with some degree of volatility that are secreted by males and females and stimulate sexual interest via the olfactory system of individuals within the same species |
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What is the male effect? |
exposure of young females or females in postpartum anestrus in some species (cows) will enter puberty or reinitiate estrus faster in the presence of males or male pheromones |
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What is the physical cause of an erection and what is its purpose |
erection results from a significant increase in blood flow to the penis and a decrease in venous outflow erection is necessary for copulation and semen deposition in the female reproductive tract |
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What part of the penis fills with blood during erection? How is damage due to such high pressure prevented? |
Blood flows into the corpus cavernosum. The blood is coming from a small artery under very high pressure filling a much larger cavity. This allows a lot of blood to be pumped in and the pressure in the corpus cavernosum to increase significantly.
Rupture is prevented by the protective covering of the fibrous tunica albuginia |
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What are the 2 types of pene, what is different about them? |
fibroelastic - during erection most change occurs in length due to the relaxation of the cremaster muscle and extension of the sigmoid flexure - increase in size of penis is limited by extensive fibrous tissue in the tunica albuginia surrounding the corpus cavernosum
vascular - during erection there is both an increase in length and diameter of the penis - a greater increase in diameter is possible due to less fibrous tissue in the tunica albuginia |
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Define reaction time as it relates to ejaculation/copulation |
the time it takes a male to and an estrous female after they are brought together |
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Define intromission |
the entry of the penis into the vagina the beginning of copulation |
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Define copulation |
consists of a series of pelvic thrusts over and interval that is unique to each species |
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Define ejaculation |
the propulsive discharge of semen from the penis during the male orgasm |
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Which came first emission or ejaculation |
emission must come before ejaculation though it may continue during ejaculation |
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What is emission |
the movement of sperm and accessory gland secretions into the urethra |
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What is the nervous system control of emission and ejaculation |
-emission: controlled by the parasympathetic nervous system in response to sensory input from the hypogastric plexus - ejaculation: controlled by the sympathetic nervous system in response to sensory stimulation of the glans penis |
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What makes up semen? |
spermatozoa (cellular component) and seminal plasma (fluid component) |
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What are some ways to increase sperm count in semen? |
sperm count can be increased through sexual preparation - false mounting - restraint before mounting
The physiological process of this involves the release of oxytocin from the posterior pituitary which causes contraction of the epididymal smooth muscle |
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Where to sperm gain their motility? |
in the tail of the epididymis - they are exposed to forward motility protein |
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On what hormone is the epididymis entirely dependent? |
testosterone |
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What physical changes occur in the epididymis? |
- alteration of cell volume - nucleus condenses - acrosome matures - migration of the proximal protoplasmic droplet |
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What could be a sign that a male is ejaculating with excessive frequency or that there has been some trauma to the epididymis? |
high concentration of sperm with protoplasmic droplets |
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What is a sign of prostatic hypertrophy in older animals? What is a proposed caused for prostatic hypertrophy? In what species does this usually occur? |
- usually occurs in dogs and humans - causes increased urination - increases in cell number are likely due to increased responsiveness of prostatic tissue to testosterone |
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What are the functions of bulbourethral gland secretions? |
- flush urine from the urethra - raise pH prior to sperm passage |
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What is seminal plasma composed of? What are its functions? |
Composed of secretions of the testes, epididymis, and male accessory glands
functions: - nourish sperm - support the metabolism of sperm - cleanse the urethra - lubricate the penis and vagina - neutralize the acidity of the female reproductive tract to enhance sperm survival |
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Would seminal plasma be more important in the bovine species or equine species? |
bovine - seminal plasma is of most importance in species whose sperm is deposited in the vagina. - cattle, sheep, rabbits, and primates all deposit sperm in the cranial vagina which horses deposit sperm in the uterus |
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What is major nutrient contained in most species seminal plasma do dogs lack? Why are they missing this? |
fructose - fructose is produced mainly in the seminal vesicles and the dog does not have these glands |
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What accessory sex gland is present in all species and what are its major secretions? |
prostate - acid and alkaline phosphatases - proteolytic enzymes - glycosidases - aspartate aminotransferase |
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What are the types of uteri? |
duplex - rabbit and guina pig - horns are separate and cervix is divided so there is no migration of the ovum Bicornuate - pig, cow, dog, ewe, mare - shared body and cervix with 2 horns, ovum can migrate Simplex - primate - a single body with no horns |
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What are the functions of prolactin in the female reproductive tract? |
- triggers the onset of lactation and contributes to CL function |
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What event determines the length of the estrous cycle? |
regression of the CL (caused by PGF2alpha) |
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What are some factors that can lead to earlier puberty in females? |
- adequate nutrition - optimal social rearing environment - crossbreeding - administration of progestins |
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What is silent ovulation? |
an ovulation without any outward signs of estrus. - this often occurs with the first ovulation after the onset of puberty |
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What are the phases of estrous cycle? |
- estrus- period of sexual receptivity - metestrus- period for the establishment of CL - diestrus- longest period, when CL is functional - proestrus- period of rapid follicular growth and regression of CL |
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Contrast the luteal phase and the follicular phase |
luteal phase - period of CL formation and function follicular phase - period for development of follicles |
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During which phase of the estrous cycle does ovulation generally occur? |
estrus |
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What hormone can induce estrus in all species? |
estradiol |
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In what species does an estrus female respond to the presence of males by standing to be mounted by other females? |
cattle |
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What is beginning of the menstrual cycle? |
menstruation- sloughing of the endometrium at the end of the luteal phase |
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How does sexual receptivity differ in menstrual and estrous cycles? |
- estrous: sexual receptivity is limited to one period of the cycle - menstrual: sexual receptivity is NOT limited to one period |
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How much of the cycle does the follicular phase make up in the estrous and menstrual cycles? |
estrous: 15-30% menstrual: 50% |
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Where does the luteolytic agent come from in the nostril and estrous cycles? |
- menstrual: ovaries - estrous: uterus |
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What event causes the change from an oogonia to an oocyte? |
beginning of the first meiotic division becomes arrested in prophase |
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What are the 2 main cell types of a follicle? Where are each located in the follicle? What is the function of each? |
Theca cells - located outside the follicle - highly vascularized - have receptors for LH and produce androgens
granulosa cells - located inside the follicle - convert the androgens produced by the theca cells to estrogen |
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What distinguishes each stage of follicular growth? |
1. Primordial follicles: contain immature oocytes showing no biologic activity 2. primary follicles: cells become cuboidal, oocytes resume meiosis, and zone pellucida forms 3. Secondary follicle: theca cells are recruited and surround the outside of the follicle 4. Tertiary follicle: fluid filled antrum develops adjacent to the oocyte, theca cells develop receptors for LH and follicles begin producing estrogen |
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Hormonally what is the difference between a viable and nonviable follicle? |
viable follicles contain more estrogen while nonviable follicles contain more androgens - this is likely because nonviable follicles have fewer granulosa cells so are not able to convert all the androgens to estrogen |
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describe the two cell two gonadotropin model for the biosynthesis of follicular estradiol |
- LH directs androgen synthesis by the thecal cells - androgens are aromatized to estrogens by the aromatase enzymes under the direction of FSH in the granolas cells |
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A surge of what hormone causes ovulation of the dominant follicle? |
LH |
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What causes atresia of the non dominant follicles of a follicular wave? |
release of estradiol from the dominant follicle resulting negative feedback on the release of FSH and thus atresia of the smaller follicles |
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What is the goal of super ovulation? What is typically used to accomplish this? |
get a group of animals to enter estrus at the same time - usually done through the administration of PGF2alpha--> causes the regression of the CL and a new period of estrus to begin |
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What is the goal of superovualtion? What hormone is usually used to accomplish this? |
goal is to produce multiple embryos for transfer to recipients FSH is administered to stimulate follicular growth |
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When trying to induce super ovulation would you be more successful if you administered FSH at the end of proestrus or the beginning? |
the end - The earlier in a follicular wave that FSH is administered the more follicles you will be able to stimulate to ovulate. - if a dominant follicle has already developed then you will not be able to induce many more to ovulate |
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What changes within the oocyte are induced by the surge in LH? |
- resumption of meiosis by inhibiting the production of oocyte maturation inhibiting factor - redirection of steroidogenesis from estrogen to progesterone |
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In induced ovulation what stimulates the LH surge? |
sensory receptors in the vagina are stimulate during copulation and send a signal to the hypothalamus to cause a release of GnRH and then LH from the pituitary |
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What changes occur with formation of the corpus luteum? |
- hypertrophy and hyperplasia of follicular cells - changes in cellular morphology to large and small luteal cells - increases in secretion of progesterone |
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Describe the process of CL formation following the LH surge |
- the basement membrane between the theca interna and granulosa cells dissolves and blood vessels invade the astral space - the astral cavity fills with blood forming the corpus hemoragicum - follicular cells grow in size (granulosa cells) and number (thecal cells) leading to formation of CL |
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Which are more responsive to LH stimulation, small or large luteal cells? Which are responsible for the secretion of progesterone? |
small luteal cells are more responsive to LH but large luteal cells secrete progesterone |
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What are the major roles of progesterone secreted from the CL? |
- increases uterine gland secretions - mediates cervical closure - increases mammary development in preparation for lactation - inhibits uterine contractions |
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Suppose you have a vet come to your farm to determine if you prize mare is pregnant. He does a rectal and determines that the mare is not pregnant because there is no CL present. Should you trust his judgement. |
- no, he obviously did't study for this test because then he would know that you can't palpate a CL in the horse |
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Describe the process of luteolysis |
- Progesterone inhibits release of LH, which maintains the CL - in late diestrus secretion of LH is lowered to a point that it can no longer maintain the CL - as CL production of progesterone declines oxytocin secretion increases. - oxytocin triggers the release of PGF2alpha - PGF2alpha mediates destruction of CL by disintegrating capillaries increasing numbers of cytoplasmic vacuoles |
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Differentiate between deep and transitional anestrus. |
deep anestrus- animal cannot be induced to reenter estrous cycle even with artificial influences
transitional anestrus- period of anestrus where animal is preparing to resume estrous cycle and can be induced to resume earlier with exogenous influences |
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You are wanting to induce estrus in you ewes so that you can breed them sooner. Your neighbor tells you that you should load them up in your trailer and drive them around for a while. Should you believe him? |
Yes, mild stress, such as that brought on by transport, has been shown to induce estrus in ewes and gilts |
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How does energy intake prepartum affect postpartum anestrus? |
the higher the energy intake prepartum the shorter the postpartum anestrus period |
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What is the goal of flushing? How is it done? |
goal is to increase ovulation rate in species that ovulate more than one ova.
it happens when an animal that is receiving suboptimal nutrition is suddenly provided much more energy |
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Would you expect to see higher conception rate in your sows in the winter ( avg 30 F) or summer (avg. 90F)? |
in the winter. Heat and humidity can depress reproduction, both estrus detection and conception, in cows and pigs |
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Primates under go menopause as they age and their ovaries become unresponsive to gonadotropins. This does not occur in non primates but they are affected by age, how? |
as they age the length of their estrous cycle increases and fertility decreases |
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In most species are oocytes ovulated first or are sperm deposited first? Why? |
sperm are generally deposited first. They have further to travel to reach the sight of fertilization (ampullary region) and they can survive for 24 hours generally while oocytes must be fertilized within a few hours of ovulation |
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What are the 2 major ways in which sperm are lost form the female reproductive tract? |
- retrograde flow - phagocytosis |
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What physiological change, in the female, increases the change of sperm being phagocytized? |
During estrus blood flow increases to the reproductive tract and brings with it increased numbers of neutrophils. the purpose of this is to defend against foreign agents that may enter during copulation but they will also recognize sperm as foreign (especially when they can't make it further through the tract because of some abnormality) and attack them |
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Do bull or stallion sperm have to travel further through the female reproductive tract? |
bull
bull semen is deposited in the cranial vagina while stallion semen is deposited in the uterus |
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What abnormalities in sperm prevent them from traversing the female reproductive tract? |
- misshapen head - non motile - protoplasmic droplet |
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What is a special property of pig semen to prevent loose of sperm by retrograde flow? |
semen has a coagulative property that forms sort of a plug to prevent sperm from being lost
horses and rodents also have similar properties |
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What are the phases of sperm transport in the female reproductive tract? |
-rapid: a few sperm arrive within minutes to the ampullary region but these are not viable - sustained: over a period of hours more and more viable sperm gradually arrive at the sight of fertilization |
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What are 3 things that contribute to the movement of sperm through the female reproductive tract? |
- secretions from the female tract - contractions of the female tract - sperm motility |
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What triggers contractions of the female reproductive tract prior to fertilization? |
- estrogens from ovarian follicles - oxytocin released from the pituitary during copulation - prostaglandins in the ejaculate |
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Describe fertilization from the viewpoint of a spermatozoa |
- You first move to cervix/uterus and undergo capacitation where the seminal plasma coat surrounding your membrane is lost - Next, you travel to the ampullary region where an influx of calcium causes you to become super hyperactive and move around a lot - Luckily all that movement increased your chances of encountering an oocyte and when you do you had so much energy that you were able to penetrate it. - once you bind to the oocyte her membrane and your acrosomal membrane fuse and you release enzymes that help to penetrate the oocyte. - once you make it all the way through the zone pellucida you bind to the microvilli of the vitalline membrane and are engulfed - you then release your genetic material and mix it up with that of the ooctye |
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Describe fertilization from the oocyte's view point |
- you are sitting around minding your own business when suddenly this sperm runs head first into your membrane and starts dissolving it. (luckily you kind of like him because he was a really fast swimmer (and you can't really do anything about it at this point anyway)) - Once he binds to your inner vitalline membrane you invite him inside and resume meiosis - your a one sperm kind of oocyte, though, so once you invite him in you release cortical granules that block other sperm from penetrating - after you complete meiosis II your genetic material mixes with that of the sperm and a zygote is formed |
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What is uterine milk? What causes its secretion? |
secretions from the uterus that nourish the embryo its release is triggered by progesterone |
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Does blastocyst elongation occur before or after hatching from the zone pellucida? |
after. Once the blastocyst escapes the zone pellucida it develops extra embryonic membranes and this process is referred to as blastocyst elongation |
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What is the signal for bovine/ovine recognition of pregnancy? |
trophoblastic proteins inhibit the release of PGF2alpha therefore preventing the destruction of the CL |
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What is the signal for the porcine recognition of pregnancy? |
estradiol causes PGF2alpha to be secreted in an exocrine fashion and it therefore cannot reach the CL |
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What is meant by the countercurrent exchange of PGF2alpha? |
PGF2alpha is rapidly destroyed in pulmonary circulation so it have a way to reach the CL, so that it can destroy it in the absence of or at the end of pregnancy, without going through pulmonary circulation.
The solution is that it diffuses down its concentration gradient from the uterine vein to the ovarian artery and therefore does not have to go through the whole circulatory loop |
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What is the mechanism of equine recognition of pregnancy? |
movement of the embryo throughout the uterus prevents the secretion of PGF2alpha |
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What is the mechanism of primate recognition of pregnancy? |
rather than inhibiting the release of luteolytic agents they secrete eCG a luteotropic agent |
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what is the mechanism of canine and feline recognition of pregnancy? |
trick question-- there isn't one canine and feline CLs have an inherent life span whether they are pregnant or not. in the dog this is the length of pregnancy, in the cat it lasts 36 days and after that an unknown factor maintains the CL |
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What is the function of the placenta? |
- an organ of nutrient, gas, and waste exchange |
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Determine if each of the following are produced by the fetus or transferred from the mother: - amino acids - fat soluble vitamins - water soluble vitamins - glucose - proteins - steroids |
- amino acids: transferred - fat soluble vitamins: produced - water soluble vitamins: transferred - glucose: transferred - proteins: produced - steroids: transferred |
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You have a star thoroughbred that is 3 months pregnant. Unfortunately you just discovered a tumor on her ovary (it is a special, immediately life threatening kind). The vet says the only way to save her is to remove the ovary. Should you be concerned about loosing the baby if you take out the ovary? |
Not because of loss of the ovary. Horses, sheep, and humans are ovariectomy tolerant meaning that most of their progesterone for maintaining pregnancy comes from the uterus so removing the ovary should not greatly affect the pregnancy. |
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What form of estrogen is produced by the placenta? by the ovaries? which is more active? |
ovaries- estradiol placenta- estrone
estradiol is more biologically active |
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What are the differences between eCG and hCG? |
duration of secretion: - eCG between days 40 and 150 - hCG throughout pregnancy where it can be detected: - eCG only in blood - hCG in blood and urine Biological activity - eCG has FSH like activity in species other than horses -hCG has LH activity |
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What causes the initial rise in serum progesterone during the pregnancy of a mare? |
- eCG maintenance of CL in the first 150 days of pregnancy - recruitment of accessory CLs due to increased FSH secretion |
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How are estrogens formed in the pregnant mare? How does this affect their concentration throughout pregnancy? |
formed from the aromatization of fetal androgens. Therefore their concentration depends on the concentration of fetal androgens.
As a result estrogen is highest during the 7-8th month of pregnancy when fetal gonads are hypertrophied and they are producing a ton of androgens
in other domestic species the placenta produces estrogen itself and the concentrations peak at the end of pregnancy |
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What is the function of placental lactogen? |
stimulates fetal growth and mammary development |
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What is the function of prolactin during pregnancy? |
prepares the mammary gland for lactation and initiates lactation |
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What is the function of relaxin during pregnancy? where is it produced in different species? |
Function: maintains uterine quiescent and prepares the reproductive tract for parturition
secretion: - CL: sow, cow, and human - placenta: cat, dog, horse |
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What triggers parturition? |
increases in fetal cortisol |
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What are the effects of increased levels of fetal cortisol? |
- induces enzymes that stimulate the conversion of progesterone to estrone and estradiol--> PGF2alpha secretion--> uterine contractility and luteolysis - causes final development of fetal respiratory tract - induces substantial glycogen deposition in the fetal liver |
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How does estrogen aid in parturition? |
increases contractility of uterus by decreasing electrical resistance and up regulating oxytocin receptors |
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What are the stages of parturition? |
-stage 1: dilation of the uterus and myometrial contractions that cause the fetus to rotate - stage 2: expulsion of fetus from reproductive tract - stage 3: expulsion of the placenta |
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In litter bearing species how many stages of parturition are there? |
2: stages 2 (expulsion and fetuses) and stage 3 (expulsion of placenta) are one event |
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When you notice an animal starting to strain during parturition, what stage is she likely in? |
stage 2. stage 1 usually has no outward signs |
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What causes dilation of the cervix? |
initially caused by hormonal effects and the contraction of longitudinal myometral muscles
during stage 2 the pressure of the fetus on the crevices induces further dilation |
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What are 2 major causes of dystocia? |
- abnormal presentation of fetus - inadequate diameter of pelvic outlet relative to size of the fetus |
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What is the puerperal period? |
the post partum period between parturition and estrus or ovulation |
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what are some nutritional diseases associated with the puerperal period? |
- ketosis - milk fever - displaced abomasum |
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What are some reproductive diseases associated with the puerperal period? |
- retain placenta - metritis - mastitis - cystic ovarian disease |
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what is foal heat? |
the first heat in a mare following pregnancy - it occurs within 8-12 days of delivery and is ovulatory so she could become pregnant |
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in most species what determines the length of the puerperal period? |
the amount of time it takes to repair the uterus |
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Describe the general organization of the mammary gland. |
Alveoli (the functional unit) are grouped into lobules, lobules are grouped into lobes
Milk drains from the alveoli into the gland cistern through large ducts
from the gland cistern milk moves to the teat cistern which terminates in the external opening, or streak canal |
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Define lactogenesis |
induction of milk synthesis- process by which alveolar cells acquire the ability to secrete milk |
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what are the 2 stages of lactogenesis? |
1. enzymatic and cytologic differentiation of alveolar secretory cells-- limited milk secretion prior to parturition
2. copious secretion of milk starting shortly before parturition and continuing throughout several days postpartum |
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what are 3 lactogenic hormones? |
- insulin - prolactin - glucocorticoids |
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How does insulin affect lactogenesis? |
- stimulates they expression of genes for the formation of milk proteins - induces sensitivity to other hormones |
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How does prolactin affect lactogenesis |
stimulates the translation of casein and other protein genes |
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How do glucocorticoids affect lactogenesis? |
actively induce differentiation of the rough ER (where proteins are synthesized) |
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what hormone blocks lactogenesis throughout most of pregnancy? |
progesterone |
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How does progesterone inhibit lactogenesis? |
- inhibits prolactin induced up regulation of prolactin receptors - inhibits translation and stabilization of milk protein mRNA by blocking prolactin - blocks prolactin induced synthesis of alpha lactalbumin |
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Define galactopoiesis |
the maintenance of lactation through maintenance of alveolar cells, synthetic activity per cell, and efficacy of milk ejection reflex |
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If an animal becomes pregnant during lactation what effect does this have on galactopoiesis? |
generally there is no effect until after the 5th month of concurrent lactation and pregnancy when mammary cell numbers decrease at a faster rate than in non pregnant animals |
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What hormones affect galactopoesis? |
-insulin -thyroid hormones -glucocorticoids -growth hormone -parathyroid hormone |
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how does parathyroid hormone affect galactopoiesis? |
increases milk yield and increases the concentration of plasma calcium |
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how do glucocorticoids affect galactopoiesis? |
stimulates alveolar cells division and activity |
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How does growth hormone affect galactopoiesis? |
indirectly by partitioning nutrients away from body tissues and toward milk synthesis |
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What are two parameters used to determine lactation efficiency? |
- peak yield - lactation persistency |
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What is residual milk volume? how does it effect lactation efficiency? |
- it is the amount of milk left over in the mammary gland following a milking - if residual volume is high then mechanical feed back will limit milk synthesis and decrease lactation persistency |
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What metabolic changes occur with lacatation? |
- increased absorptive cells in the digestive tract and liver -increased food and water intake - decreased energy and nutrient demand from peripheral tissues |
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What function do each of the following organelles play in milk synthesis? - ER and golgi apparatus -mitochondria - cytoplasm - lysosomes |
- ER and golgi: sight of protein synthesis, processing and packaging - mitochondria: energy production and synthesis of citrate for production of amino acids - cytoplasm: sight of glycolysis, fatty acid synthesis, and amino acid activation - lysosomes: destroy cell at the end of lactation
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Where does the glucose in milk come from in ruminants and non ruminants? |
ruminants- synthesized from acetate and proprionate
nonruminants- dietary glucose |
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What is a glucose sparing mechanism? |
mechanism employed by ruminants where glucose is not used in reactions that could use something else so that it can be saved for milk production |
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What are 3 major sources of fatty acids in the mammary gland? |
- synthesis from acetate and beta-hydroxybuterate - triglycerides in chylomicrons and LDLs - acetyl CoA from glycolysis and the citric acid cycle |
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What are the 3 major milk proteins |
- casein - alpha-lacalbumin - beta- lactoglobulin |
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What enzyme is responsible for the formation of lactose? What molecules does it use? |
lactose synthase uses glucose and galactose to form lactose- the major carb in milk |
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Describe the structure of lactose synthase. What is the rate limiting component of this enzyme? |
composed of 2 subunits: galactosyltransferase and alpha-lactalbumin
alpha lactalbumin is only found in milk and is the rate limiting component of lactose synthase |
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What 4 molecules are responsible for maintaining the osmotic equilibrium of milk and blood? What does this mean from a milk production standpoint? |
1. lactose 2. potassium 3. sodium 4. chloride
The greater concentration of these in milk the greater the volume of milk because they will draw more water in |
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How are nonfat components of milk secreted? |
packaged into vesicles in the golgi apparatus and expelled from secretory cell into lumen by exocytosis |
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How are lipid components of milk secreted? |
form droplets that combine in the cytoplasm and bud off into the lumen |
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What regulates the rate of milk secretion? |
- pressure within the gland - chemical feedback by milk components (specifically whey protein) |
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Manual milking uses _________ to release milk and resembles how ________ nurse, while a milking machine ________ and resembles the nursing technique of _________ |
Manual milking uses mechanical force to release milk and resembles how goat kids nurse, while a milking machine creates a vacuum and resembles the nursing of a calf |
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What is the mechanism of milk evacuation? |
a pressure differential is created between the mammary ducts and the ambient surroundings sufficient to force milk to leave the gland.
The positive pressure within is created by milk in the gland
the negative pressure without can be created with mechanical force or by creating a vacuum |
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Stimulus of the teats during milking can induce milk release, what can inhibit it? Describe the mechanism of this inhibition. |
the release of catecholamines in response to stress - constrict blood vessels which prevents oxytocin from reaching gland - directly block the binding of oxytocin - block the release of oxytocin |
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What is the difference in immunoglobulin concentration in the milk of primates and ruminants? Why is there this difference? What is the result? |
ruminants: mostly IgG, provides systemic immunity, they are unable to transfer antibodies across the placenta
primates: mostly IgA, provides local immunity, they can transfer all necessary antibodies across the placenta |
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Is milk more important to the growth and survival of guinea pigs or primates? |
primates |
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What is lactation capacity? |
the maximum energy transferred via milk |
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What affects lactation capacity? |
- physiological status of nursling - growth rate of nursling - genetic pattern - environmental stress - nursing habits - availability of food and water |
