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Test 3

3 requirements to meet before sperm can be produced. 1) Adequate GnRH release (high freq./low amp) 2) FSH/LH from Anterior Pituitary 3) Secretion of gonadal steroids (High conc. test in testis, low conc. test in systemic blood)
What is the frequency and amplitude of GnRH from the tonic center in a male? High frequency, low amplitude pulses
Are LH patterns different or similar to GnRH secretion patterns? Similar -- follows pattern -- released for 10-20 minutes, 4-8 times per day
Is FSH secretion higher amplitude or lower amplitude than LH? Why? FSH is lower than LH -- due to inhibin from the testes
Are FSH secretions longer or shorter than LH? Why? FSH longer than LH -- FSH has a longer 1/2 life
What is inhibin? Where is it released from? Hormone that provides negative feedback against FSH -- testes and ovaries
Where does LH bind? To Leydig cells
Why should testosterone match LH secretion? Because LH binds to Leydig cells -- which releases testosterone
What is the FSH peak not sharp? Due to its half life
Does testosterone peak before or after LH binds to leydig cells? After LH binds
Is LH a protein hormone or steroid hormone? Protein hormone
When LH binds to membrane receptors on Leydig cells, what is converted to testosterone? Progesterone
Is testosterone released in long, consistent waves or short pulses? Short pulses
Why is it important to have LH pulses instead of consistent release? High concentration of testosterone is important for spermatogenesis, but leydig cells become refractory to high concentrations of LH which leads to low testosterone (receptors downregulate) -- so it needs slow stimulation over time
Why is LH the main negative feedback hormone rather than testosterone? Testosterone is quickly diluted in blood and has a short half life (cant have strong negative FB on GnRH). If released in high concentrations, neg FB of GnRH/LH/FSH (negative FB on spermatogenesis--not good)
What cells are FSH receptors on in a male and female? Sertoli and Granulosa
What cells are LH receptors on in a male and female? Leydig and Theca
What enzyme converts testosterone to Estrogen? Aromatase
What are two ways estrogen can be produced in a male? By using aromatase within the Leydig cell to convert testosterone to estrogen -- When testosterone is released from Leydig cell to blood, Sertoli cells can convert it to estrogen
What are two things that sertoli cells convert testosterone into? Estradiol and DHT
What is the role of estradiol that is released from Sertoli cells? Negative feedback of GnRH -- more control on LH
Where is inhibin produced in a male? In Sertoli cells
What is the theory for making estrogen? 2-cell-2-gonadotropin theory
What is the dominant structure in the Follicular Phase? What is the dominant hormone? Follicle is dominant -- estradiol is dominant hormone
What is the dominant structure in the Luteal Phase? What is the dominant hormone? Corpus Luteum is dominant structure -- Progesterone is dominant hormone
What day does ovulation occur in estrous? Day 0
What day does menses occur in menstrual cycle? Day 0
Compare what happens on day 0 of menstrual vs estrous Menses - men
What % of estrous is follicular and luteal? 20% follicular, 80% luteal
What % of menstrual is follicular and luteal? 50% follicular, 50% luteal
What is the difference between estrus and estrous? Estrous (adj.) - cycle -- series of predictable events that begin at Estrus and end at end of subsequent Estrus Estrus (noun) - period of sexual receptivity
What is Estrus greek for? Gadfly, Sting, Frenzy
What is Gadly, Sting, Frenzy? Animal acts as if they have been bitten and then exhibits wild behavior when in estrus
What is the average length of estrus? What is it dependent on? 20 days, but species dependent
What are 3 categories of Estrous? Polyestrus, Seasonal polyestrus, monoestrus
What is Polyestrus? uniform distribution throughout year, may become pregnant regardless of season
What animals exhibit polyestrus? Cow, pig, queen, rodent
What is seasonal polyestrus? Cycle during certain seasons -- cluster of estrous cycles (short day breeders and long day breeders)
When do short day breeders mate? What are examples of these animals? Fall -- ewe, doe, elk, nanny
When do long day breeders mate? What are examples of these animals? Summer -- mare
What is monoestrus? One cycle per year or 3 cycles per 2 years
What are examples of monoestrus animals? Dogs, wolves, foxes, bears, domestic canids
What is unique about the estrus of monoestrus animals? Have estrus that lasts several days -- time between ovulation and fertilization
Why do dogs have time between ovulation and fertilization? So the dog can mate with multiple males
What events does the follicular estrous phase consist of? Regression of CL to ovulation (Proestrus and Estrus)
What events does the luteal estrous phase consist of? Ovulation to CL regression (Metestrus and Diestrus)
What is proestrus? Progesterone declines do to CL regression -- 2-5 days -- transition from P4 to E2 dominance -- formation of ovulatory follicles and estradiol secretion
Does estrogen affect progesterone or does progesterone affect estrogen? Progesterone affects estrogen
Where is PGF-2 alpha from in most animals? Uterus
What is estrus? Sexual receptivity and mating period -- major physiological changes in tract -- peak estrogen
What is the different between the female mounting and the female being mounted in estrus? Female who mounts in in proestrus -- female being mounted is going to ovulate in 12 hours (is in estrus)
What is metestrus? CL formation and beginning of progesterone secretion -- both estrogen and progesterone high
What is Diestrus? Longest stage of cycle -- CL fully functional, Progesterone peaks, ends with luteolysis -- progesterone prepares uterus for possible pregnancy -- lasts 10-14 days
If pregnancy occurs in animals, what estrous phase continues? Diestrus
What animals are induced ovulators? cats, alpaccas, llamas
What do induced ovulators need to ovulate? Vaginocervical stimulation
What stimulates behavioral estrus in induced ovulators? Increased levels of estrogen stimulate this
What does vaginocervical stimulation activate? Activates a neuroendocrine reflex resulting in a GnRH release -- results in LH surge -- ovulation -- progesterone will maintain pregnancy if necessary
What is different about a queen's estrous cycle? How do P4 levels look? They only have estrus and proestrus -- P4 is always low unless pregnant
In a dog, what is unique about FSH? An FSH surge occurs directly after ovulation -- always recruiting new follicles
In a dog, what hormone rises during anestrus? Inhibin and Estrogen (estrogen rise signals follicular development)
What is diapedisis/pseudomenstration? Uterine vessels leaky due to elevated estrogen -- bleeding in proestrus period (not same mechanism as menses -- hormone withdrawal)
How can you determine the day of a cycle in rodents? By doing a vaginal cytology -- when in estrus, high population of cornified epithelium
If there is no mating with rodents, what happens to CL? CL is non-functional, lasts 2 days, cycle moves to diestrus
If there is mating with rodents what happens to CL? CL maintained by prolactin for 12 days = pseudopregnancy -- no pregnancy, CL regresses -- pregnancy, maintained by placental P4
How is prolactin formed? By mating
What is anestrus? Ovaries inactive, no functional CL, no ovulatory follicles
What are 3 reasons for anestrus? 1) insufficient GnRH -- 2) lactational anestrus -- 3) seasonal anestrus
What is the cause and effect of insufficient GnRH and anestrus? Pregnancy causes -- progesterone high (from CL and placenta) -- negative FB on GnRH neurons -- No FSH/LH -- No follicular growth -- No ovulation
What is lactational anestrus? type of postpartum anestrus -- often used to synchronize estrus -- allows uterus to repair before estrus -- suckling activity inhibits FSH, LH -- nervous system thought to control
What are two exceptions of animals with lactational anestrus? Tammar Wallaby and Beef Cattle
What is unique about the Tammar Wallaby? It has embryonic diapause -- embryo formed but stays in blastocyst phase unti lactation is complete
What is unique about beef cattle and lactational anestrus? Lactation alone does not effect estrus -- other factors may be involved such as visual encounters and olfactory and auditory encounters with offspring
What type of cattle does not experience lactational anestrus? Dairy cattle -- calf is immediately removed, usually milk mother for period of time, dry period, then breed again
What is seasonal anestrus? prevents pregnancy from occurring during period of low food availability -- high temperature causes low sperm count -- embryo can experience heat shock
What are animals that cycle in the fall? When do they give birth? Short day breeders -- birth in spring -- sheep, deer, elk
What are animals that cycle in the summer? When do they give birth? Long day breeders -- birth in spring -- mare
What do animals that have seasonal anestrus have? Photoperiod
What does photoperiod control? the transition between cyclicity and anestrus to cyclicity
What is the onset of seasonal cyclicity similar to? Puberty -- dependent on GnRH
What chemical can stimulate or inhibit GnRH? Melatonin
How does high melatonin affect long day breeders and short day breeders? High melatonin in long day breeders causes low GnRH -- High melatonin in short day breeders causes high GnRH
What does GnRH amplitude and frequency look like in anestrus? Low amplitude, low frequency
Is melatonin high when it is dark or light? Dark
If you inhibit your pineal gland, is melatonin high or low? Low
When you do not inhibit your pineal gland, is melatonin high or low? High
What day of the menstrual cycle does ovulation occur? Day 14
Does menstrual cycle have a defined period of sexual receptivity? When? No -- they don't
How is menses defined? Sloughing of endometrium to exterior -- menstrual period
How long is the average menstrual cycle? 28 days
What effect does estrogen have on endometrium? High E2 makes endometrium THICK
What effect does progesterone have on endometrium?
What two phases of menstrual cycle are part of follicular phase? How long are each of these? Menstrual (5 days) and Proliferative phase (9 days)
What are characteristics of menstrual phase? Contraction/relaxation of spiral arteries, shedding of necrotic endometrium, decreased steroid production, release inflammatory mediators, PGF2alpha, cytokines, NO released, thin layer of epithelium remains
What are characteristics of proliferation phase? Endometrium increases thickness, re-epithelialized by day 4-7, endometrial glands increase in size (straight and narrow)
What phase is part of the luteal phase of menstrual cycle? How many days does it last? Secretory phase (14 days)
What are characteristics of secretory phase of menstrual cycle? P4 increases dramatically, E2 increases, further enlargement of endometrium, glands increase in size and number (highly coiled and secretory), if no pregnancy = CL regression
What is menopause? What is is analogous to in the estrous cycle? No cyclicity, ovaries not producing E2, similar to pre-pubertal state -- analogous to anestrus
What is amenorrhea? Absence of menses during reproductive age due to lack of energy balance, stress, fatness/nutrition issues
What is lactation regulated by? What does this hormone affect? Prolactin -- increase in prolactin causes decrease in GnRH frequency and amplitude
What is used as an alternate form of contraception after birth? Lactation -- not that effective (only 75%)
In the surge center, what effect does E2 have? Frequency/Amplitude levels? Positive FB -- high amplitude and frequency of GnRH
Positive FB of estrogen to surge center only works in absence of ______? Progesterone
How does estrogen affect tonic center? High levels provide negative FB to tonic center -- keeps amplitude low and frequency high (GnRH/FSH/LH)
What effect does high progesterone have on hypothalamus? High progesterone in Luteal Phase provides negative FB to hypothalamus only (low amp/freq of GnRH)
During the follicular phase, which hormones are low and which are high? Luteolysis occurs, so progesterone is low -- negative FB on hypothalamus removed -- FSH/LH increase -- estrogen dominant (follicles present)
What two hormones are high during follicular development? Inhibin (reduces FSH) and Estradiol (Preovulatory LH Surge)
What is the cycle of mature oocyte formation? Primordial -- Primary -- Secondary -- Tertiary
When does oogenesis begin? When do they fully mature? Begins during fetal development (approximately 20 weeks, antral after 26 weeks). Fully mature after LH surge.
How does LH affect an oocyte? Reduces egg from 2n to 1n = reduces chromosome #
What is folliculogenesis? Oocyte develops within the somatic cells of the ovary (granulosa and theca) -- matures into fertilizable oocyte
If oogenesis and folliculogenesis don't work together, what happens? Repro failure
Does granulosa or theca develop first? Granulosa first then theca second
What types of cells are primordial cells? Squamus
What stage do primordial follicles enter into until LH surge occurs? Entered diplotene of prophase 1
How many cells does a fetus begin with? What is that number at birth? 6-7 million -- 400,000 at birth
By puberty, how many eggs are lost? At age 37? Age 50? 90% lost -- approx 25,000 at age 37 -- 1,000 at age 50
How many eggs do you actually ovulate in your reproductive yeras? 400
What cells are primary follicles made of? Cuboidal (granulosa) - 1 layer
What cells are secondary follicles made of? at least 2 layers of granulosa cells -- no fluid/antrum -- start to form theca layer
What cells are tertiary follicles made of? 2+ layers of granulosa, theca will form 2 layers (theca interna and externa) -- antrum formed
Are FSH/LH present in primordial cell recruitment? No
Which cell recruitment phase is when gonadotropin goes from being idependent to dependent? Primary follicle recruitment
When does cyclic recruitment begin to happen rather than initial recruitment? During secondary follicle recruitment
What are the stages of recruitment from initial to cyclic? Primordial (initial) -- Puberty -- Primary(Cyclic) -- Recruitment Secondary (Cyclic) -- Selection Tertiary (Cyclic) -- Dominance (potential to ovulate)
When do FSH receptors appear on granulosa cells? During secondary follicle recruitment
When do LH receptors on Theca and RSH receptors on Granulosa appear? During Tertiary Selection
What cells and receptors are present during dominance of cyclic recruitment? FSH-R on Granulosa, LH-R on Granulosa and Theca
What is the 2-cell-2-gonadotropin theory responsible for? Estradiol production
Created by: 1363731667