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27 Cards in this Set
- Front
- Back
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What does GnRH and Gonadotropins do?
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GnRH:
-stimulates synthesis and release of LH and FSH Gonadotropins: -cAMP second messenger |
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What does Leptin do?
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has a permissive effect on the onset of puberty
in absence of leptin there is a delay in puberty |
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What are properties of Hormones during puberty?
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hormone level increases with puberty, silent in the first few years after birth
at menopause, FSH and LH are high FSH and LH only present from puberty to menopause |
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What are some signs of puberty in males?
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enlargement of testes
increase in testosterone secretion development of sex specific secondary sex characteristics puberty is earlier in females than males, girls are bigger than boys at pre-pubertal age the epiphyseal fusion is brought abotu early in females, stopping growth at an earlier age than males |
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What are structural components of the testes?
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seminiferous tubules:
-site of spermatogenesis -3 cell types: spermatogonia, spermatocytes, and sertoli cells Interstitium: -contain leydig cells |
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What are the functions of Leydig and Sertoli cells?
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Leydig cells:
-endocrine and paracrine - secretion of androgens and paracrine agents sertoli cells: -endocrine and paracrine -secretion of inhibins --> lowers FSH and spermatogenesis -secretion of MIF during embryonic life -secretion of H-Y antigen -form blood-testes barrier Inhibin can be used as a contraceptive by inhibiting spermatogenesis |
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What are some regulations of spermatogenesis?
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Extrinsic regulation - local temperature:
-inside the scrotum is 1-2 degrees C below body core temperature, essential for normal growth of sperm -increasing temperature inhibits spermatogenesis |
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What is Cryptorchidism?
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testes descend into the abdominal cavity, leading to defective spermatogenesis because the inside body temperature is too high
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What do FSH and LH do?
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FSH:
-stimlulate sertoli cells, essential for spermatogenesis LH: -stimulate secretion of androgens by Leydig cells -Leydig cells then increase testosterone |
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What do Androgens, Estrogens, Prolactin, and GH do in regulation of spermatogenesis?
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Androgens:
-lack of androgens causes cessation of spermatogenesis Estrogens: -essential for spermatogenesis Prolactin: -act on leydig cells to enhance effect of LH GH: -controls metabolism of testis |
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What is a characteristic of Testosterone?
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it is a steroid derivative
uses the same cholesterol desmolase in its reaction derived from cholesterol |
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What are some biological effects of androgens?
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androgenic:
-stimuate growth of male reproductive system and sex specifc secondary sexual characteristics anabolic: -growth promoting effects on somatic tissues and visceral organs -athletes take androgens to enhance performance because of anabolic effects |
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How are androgens regulated?
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Testosterone and estrogens inhibit release of GnRH, LH, and FSH
Inhibins primarily inhibit FSH secretion Testosterone converted to estrogens in the HT and pituitary to exert effect on GnRH and gonadotropin secretion. |
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What are produced by the ovarian follicles and the corpus luteum?
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ovarian follicles:
-Estrogens (Estradiol) Corpus Luteum: -Progesterone -formed after ovulation takes place |
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What are some biological effects of Progesterone?
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increase protein anaboilsm
increase respiration stimulates appetite; has anesthetic effects |
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What are some biological effects of Estrogen?
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development of ovarian granulosa cells
stimulates prolactin secretion blocks prolactin action on breast suppression of ovulation vasodilatory effects, cholesterol lowering action |
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What do LH and FSH do?
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LH:
-give rise to Theca cells -formation and maintenance of corpus luteum -highest during ovulation FSH: -give rise to Granulosa cells -increase follicular growth and development |
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What is the Ovarian cycle?
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composed of two phases: follicular phase and luteal phase separated by ovulation
length = 28 days follicular phase - begins with onset of menstruation, can be from 9-23 days ovulation - lasts 1-3 days luteal phase - more constant length, 14 days |
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What happens in the Follicular Phase?
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Formation of primary follicle:
-growth of primary oocyte -development into granulosa cells Secondary Follicle: -formation of theca layer -development of hormonal receptors: Granulosa cells for FSH and estrogen, Thecal cells for LH Antral follicular growth -proliferation of granulosa cells Preovulatory stage: -formation of Graafian (mature) follicle -fully grown oocyte resumes meiosis (stimulated by LH) |
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WHat is the Luteal phase?
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after ovulation remaining granulosa cells go into theca-lutein cells which form corpus luteum
Corpus luteum: -life span is 12 days -maintained by hCG -4 stages: proliferation, enlargement, secretion, and degradation |
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What is the Endometrial cycle?
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menstruation:
-shedding of the functional layer of the endometrium Menstrual flow (3-5 days) |
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When is each hormone highest?
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Estradiol - right before ovulation, in the proliferative phase of the follicular phase
LH - highest at ovulation FSH - spikes up a little at ovulation, same time as LH Progesterone - highest right after ovulation, when LH goes down |
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What are some menstrual disorders?
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Amenorrhea - absence of menstrual periods
Primary: failure of menstruation to start at puberty (delayed onset of menstruation), signs of deficiency of female sex steroids Secondary: cessation of menstruation after puberty Oligomenorrhea - irregular menstrual periods, less fluid excretion Dismenorrhea - painful menstruation Primary: not associated with pelvic disease, caused by excessive production of prostaglandins Secondary: IS associated with pelvic disease Anovlulatory cycles: -insufficient amount of estrogen to induce a midcycle peak of LH secretion and ovulation Polycystic ovary syndrome: -elevated LH/FSH ratio, causing excessive production of androgens |
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What is menopause?
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cessation of ovarian activity and menstruation
occurs around age 50 mechanism: -depletion of ovarian follicles -low plasma conc. of estrogens -increase LH and FSH signs: -amenorrhea -"hot flashes" -hirsutism (virilization): male pattern of body hair -osteoporosis -increase risk of atherosclerosis and coronary heart disease due loss of beneficial effects of estrogens |
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What are characteristics of Melatonin?
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derived from tryptophan
levels of secretion depend on dark-light cycle: -decrease during light period of day -highest at night, maximum - midnight functions: -regulation of circadian rhythm -antigonadotropic effect: decrease melatonin secretion plays a role in onset of puberty -antioxidant: protects against free radicals Mechanism: -light falls on retina, leads to HT to regulate circadian rhythm. From here endocrine, metabolic, and behavioral changes happen |
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What Pathophyisology is involved with Melatonin?
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pyschoses:
-seasonal affective disorder ("winter depression"): short day lengths jet-lag: -alteration of behavior, endocrine, and metabolic rhythms due to change in time zones melatonin pills: -facilitate process of adaptation to a new time zone |
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What are the roles of Leptin?
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protein encoded by obesity gene
acts as "fat sensor" increase in leptin: -increase secretion of MSH, plays role in sleep -increase SNS activity: increase metabolic rate -decrease secretion of NPY: NPY is hormone which stimulates appetite and food intake effects: -lowers food intake -increase energy expenditure mutation of leptin leads to obesity |
