Reproductive System Flashcards
run down of reproductive structures
-gonads produce gametes
-ducts recieve and transport gametes
-accessory glands secrete fluids into ducts
-perineal structures collectively known as external genetalia
how many sperm do males produce a day
-half a billion
male reproductive system
-testes that secrete male sex hormones and produce male gametes
femal reproductive system
-ovaries that release on immature gamete per month and produce hormones
-uterine tuves carry oocytes to uterus
-uterus encloses and supports developing embryo
-vagina connects uterus with exterior
pathway of sperm
-testis
-epididymus
-ductus deferens
-ejaculatory duct
-urethra
accessory glands that secrete fluids into the duct
-seminal glands
-prostate
-bulbo-urethral glands
scrotum
-fleshy pich that encloses testes
-suspended inferior to perineum
-anterior to anus
-posterior to base of penis
photo of male repro
accessory glands photo
what moves sperm from testes
-cilia lining the efferent ductules into the spidydmus
temperature regulation in testes
normal sperm development requires temperatures 1.1degrees below body temp
-muscles relax and contract to move testes to maintain temp
mitosis
-somatic cell divison
-produces two diploid daughter cells
-both daughter cells have identical numbers and pairs of chromosomes
-members of each pair are homologous chromosomes
meiosis
-special form of cell division involved only in production of gametes
-produces haploid gametes each with 23 chromosomes
-fusion of male and female gametes produce a zygote with 46 chromosome
each chromsome in meiosis has
-two chromatids
synapsis
-maternal and patermal chromosomes come together
-four mathces chromatids form tetrad
-crossing over - exchange of genetic material that increase genetic variation among offspring
meiosis I - prophase and metaphase I
-prophase I - nuclear envelope disappears
-metaphase I - tetrads line up along metaphase plate
anaphase I
-tetrads break up,
-two copies of either maternal or paternal chrom to each daughter cell
-maternal and paternal components are randomly and independently distributed
telophase I
-ends with formation of two daighter cells with unique combination of chromosomes
reductional division
-reduces number of chromosomes from dipoid to haploid
-both cells contain 23 chromosomes with two chromatids each
interphase
seperates meioisis I and meiosis II
-very brief
-DNA is not replicated
Meiosis II
-prophase II
-metaphase II
-Anaphase Ii - chromatids seperate
-telophase II - yields four haploid cells each containing 23 chromosomes
-equational division - number of chromosomes is unchanged
sperm production important times
-begins at puberty
-continues past age 70
-complete process takes about 64 days
-three steps - mitosis, meiosis and spermatogenesis
spermatogonia
-divides by mitosis to produce two daighter cells
-one ramins a spermatognium
-second differentiates into primary spermatocyte
primary spermatocyte
-begin meiosis and form secondary spermatocyte
spermatids
-secondary spermatocytes differentiate into spermatids
spermatids
-immature gametes
-differentiate into sperm
sperm
-lose contact with wall of seminiferous tubule
-enter fluid in lumen
mitosis of spermatogonium
meiosis I of spermatogenesis
meiosis II of spermatogenesis
s
second part of meiosis II of spermatogenesis
nurse cell photo
stages of spermatogenesis within the wall of a seminiferous tubule
the differentiation of spermatid into sperm
spermiogenesis
-last step of spermatogenesis
-each spermatid matures into one sperm
-major strucutral changes
-at spermiation a sperm loses attachment to nurse cell and enters lumen of ST
support of spermiogenesis
-nurse cells surround spermatids, provide nutrients and chemical stimuli for development, and phagocytoze cytosplasm shed by developing spermatids
sperm leaving epididymus
-mature but immobile
-to become motile and fully function sperm has to undergo capactiation
-capacitation steps
-1 sperm become motile when mixed with secretions of seminal glands
-2- sperm become capacle of fertilization when exposed to female
mature sperm lack
-ER
-GA
-lysosomes and peroxisomes
-inclusions
-loss of organelles refuces size and mass
-sperm must absorb nutrients from surrounding fluid
nurse cells
-sertoli cells
-maintain blood, testis barrier
-support of mitosis and meiosis
-support of spermatogenesis
-secretion of inhbin
-secretion of androgen binding protein
inhibin
-depresses pituitary production of FSH, and perhaps hypothalamic secretion of GnRH
-regulation of FSH and GnRH by inhibin allows negative feedback control of spermatogenesis
-as rates of sperm production increase, secretion of inhibin increases
Androgen binding protein
-binds androgens (primarily testosterone)
-in luminal fluid of ST
-important for elevating androgen concentration and stimulating spermatogenesis
-production of ABP is stimulated by FSH
nurse cells are stimulated by
FSH and testosteron
stimulation of nurse cells promote
-division of spermatogonia
-meiotic division of spermatocyte
blood testis barrier
-isolated ST from general circulation
-nurse cells maintain this barrier
-nurse cells joined by tight junctions dividing ST into compartmments
-outer basal compartments contain spermatogonia
-inner luminal compartments is where meiosis and spermiogenesisi occur
FSH and testosterone influence/control
-target nurse cells of ST
-nurse cells secrete inhibin and ABP, and promote spermatogenesis and spermiogenesis
GnRH hormal influence and control
-gonadotroping releasing hormone
-synthesized in hypothalamus
-carrier to pituiatry by hypohyseal portal system
-secreted in pulses (60-90min intervals)
-controls rate of secretion of FSH and LH and testosterone
inhibin influence and control
-inhibits FSH production in pit. gland
-perhaps supresses secretion of GnRH at hypothalmus
-faster rates of sperm production cause more inhibin to be secretes
LH influence and control
-targets instersitial endocrine cells of testes
-induces secretion of testosteron and other androgens
testosterone influence and control
-sexual function
-steroid homrones
-circulates in bloodstream bound to one of two transport protein
-diffuse across target cell membrane and binds to intracellular receptor
effects of testosterone
-stimulates spermatogenesis
-libido
-stimulates bone and muscle growth
-establishes and maintaines male secondary sex characteristics
-maintains accessory glands and organs of male reproductive system
DHT
-dihydroxytestosteron
-some testosterone converted to DHT in target tissues
-some DHT diffuses into bloodstream
-can binds to same receptors as testosterone
-some tissues respond to DHT instead of testosterone
estradiol
-small amount in plasma of males
-formed by testosterone by aromatase
-production increases in older men
oogenesis timeline
-begins before birth
-accelerates at puberty
-ends at menopause
fetal ovaries
-contain oogonia that undergo mitosis and produce diploid primary oocytes
oogenesis at birth
-ovaries contain 2 mil primary oocytes
most oocytes degenerate in atresia
-oocytes that survive remain at prophase I until puberty
oogenesis at puberty
-400 000 primary oocytes remain
-some are stimulated to finishe meioisis I producing haploid secondary oocytes
mitosis of oogonium
meiosis I of oogenesis
oogenesis
-cytoplasm of primary oocytes ivides unevenly producing one secondary oocyte with most of original cytoplasm
-two or 3 polar bodies that disintegrate
-ovary release secondary oocyte thats suspended in metphase II
-Meiosis II is completed upon fertilization after which a mature ivum is formed
process of oogenesis
-primary oocytes remain suspended in development until puberty
-at puberty FSH rises starting ovarian cycle
-each month after, some primary oocytes are stimulated to develop further
Meiosis II of oogenesis
ovarian follicles
-specialized structures in cortex of ovaries
-oocyte growth and meiosis I occur
primary oocytes
-located in outer part of ovarian cortex near tunica albuginea in clusters called egg nests
primordial ovarian follicle
-primary oocyte and its surrounding follce
-zona pellucida - area of intermingling microvilli of follcile cells and surface of oocyte
primordial ovarian follicles in egg nest
secondary ovarian follicle
-forms from primary ovarian follicle
tertiary ovarian follicle
follicular fluid accumulated between inner and outer cellular layers
-twice the size of secondary ovarian follicle
follicular phase (preovulartory phase)
-tertiary ovarian follcile creates bulge in ovary
-oocyte and its follicular cells project into antrum
-rising LH levels prompt completion of meiosis I
-corona radiata are granulosa cells that remain associated with secondary oocyte
luteal phase - post ovulatory phase
-corpus luteum
corpus luteum
-forms fromremaining granulosa cells under stimulation of LH
-yellow due to cholesterol
-cholesterol converted to progesterone to prep uterus for pregancy
-secretes modetae amount of estrogens
-begins degenrating 12 days after ovulation
ovulation
-tertiary fllicle releases secondary oocyte into pelvic cavity
-oocyte moves into uterine tube by contact with fimbriae or by fluid currents
-ovarian follicles that started but did not complete development undergo atresia
photo of follicle development
uterine cycle (menstrual cycle)
-repeating series of changes in endometrium
-lasts from 21-35 days, averaging 28 days
-
menarche
-first uterine cycle
-begins at puberty (age 11-12)
menopause
-termination of uterine cycle
-age 45-55
three phases of uterine cycle
-menstrual phase
-proliferative phase
-secretory phase
menstrual an proliferative phases occur when
-occur during ovarian follicular phase
secretory phase occurs when
-during ovarian luteal phase
menstrual phase
-degeneration of endometrial functional layer occuring in patches and leads to menstruation
-caused by constriction of spiral arteries reducing blood flow, oxygen and nutrients
-weakened arterial walls rupture releasing blood into connective tissues of functional layer
proliferative phase
-epithelial cells of uterine glands multiply and spread across endometrial surface and restore integrity of epithelium
-further growth and vascularization completely restore functional layer
-occurs at the same time as enlargement of tertiary follicles
-stimulated and sustained by estrogens secreted by developing ovarian follicles
-entire functional layer is highly vascularized
-small arteies spiral toward inner surface from larger arteries in mymometrium
secretory phase
-uterine glands enlarge increasing rate of secretion
-arteries of uterine wall elongate and spiral through functional layer
-begins at ovulation and persists as long as CL remains instact
-secretion peaks about 12 days after ovulation
-generally lasts 14 days
-ends as CL stops producing hormones
menses
-entire functional layer is lost rhough esternal os ad vagina
-only functional layer is affected (deeper layer supplied by straight arteries)
-35-50mL blood lost
dysmenorrhea
-painful menstruation
-several causes
hormones influence on the reproductive cycle
-GnRH from hypothalamus changes in pulse freuqnecy and amplitude over course of ovarian cycle
-estrogens increase pulse frequency
-progesterone decrease pulse frequency
-groups of endocrine cells in anterior pituiatary respond to different GnRH pulse frequencies, sensitive to some insensitive to others
increased pulse frequency of GnRH
-stimulates LH secretion
hormone on day 10 of ovarian cycle
-effect of estrogen on LH secretion changes from inhibition to stimulation
-switchover occurs when levels of estrogens exceed threshold value for about 35 hours
day 14 of ovarian cycle hormones
-massive release of LH from anterior lobe of pituitary gland
sudden surge in LH concentration triggers
- completion of meioisis by pirmary oocyte
- rupture of follicular wall
- ovulation
hormonal regulation of follicular phase
-FSH stimulates follicular development
-Monthly, some teritary ovarian follicles begin to grow
-As follicles enlarge, thecal endocrine cells produce androstendione
androstenedione
-intermediate steroid hormone
-absorbed by granulosa cells and converted to estrogens
thecal endocrine cells
-in ovarian stroma
-secrete small amounts of estrogens
circulating estrogens
-bound primarily to albumins
-lesser amounts carried by gonadal steroid binding globulin
-three types: estradiol ,estrone and estriol
estradiol
-most abundant
-most pronounced effect of target tissues
-dominant hormone prior to ovulation
estrogen synthesis
-androstenedione is converted to testosterone
-aromatase converts testosterone to estradiol
-estrone and estriol are synthesized directly from androstenedione
conversion of progesterone and androstendione to other estrogens
six functions of estrogens
-stimulate bone and muscle growth
-maintain female secondary sex characteristics
-affect CNS activity, especially in hypothalamus where estrogens increase sex drive
-maintian functional accessroy repro glands and organs
-initiate repair and growth of endometrium
-maintain thin/uncalcified vascular plaque thereby reducing CV risk
hormonal regulation of luteal phase
-high LH levels that promote progesterone secretion and trigger formation of CL
-low frequency of GnRH pulses stimulates LH secretion more than FSH secretion
-LH maintains structure and secretory function of CL
luteal phase progesterone levels
-progesterone levels remain high for 1 week
-CL degenrates unless pregnant
-progesterone and estrogen levels drop
-GnRH pulse freuquency increase stimulating FSH secretion and ovarian cycle begins again
ovarian cycle hormone levels graph
hormonal regulation of uterine cycle
-proliferative phase continues until rising progesterone starts secretory phase
-increase in estrogen and progesterone causes enlargement of uterine glands and increase in secretory activities
hormones and body temp
-monthly hormone fluctuations affect core body temp
-follicular phase, estrogens dominate and basal body temp drops 0.3 degrees
-during luteal phase, progesterone dominates
-upon ovulation basal body temp decreases briefly
-a day after ovulation, temperature rises and remains high throughout luteal phase
endometrial changes graph
aging effects on male and female repro system
-female - menopause
-male - comparable age related changed occur gradually over longer time period
perimenopause
-interval immediately preceding menopause
-ovarian and uterine cycles become irregular due to shortage of primordial ovarian follicles
-levels of estrogens decrease and ovulation may not be triggered
menopause
-time that ovulation and menstruation cease
-typically occurs at age 45-55
-age 50 = typically no primarodial follicles left
-premature menopause, depletion of primrodial follicles before age 40
-circulating concentrations of estrogens and progesterone decline
-rise in GnRH, FSH, LH sharply
male climactric (andropause)
-period of declining repro function
-between ages 50 and 60
-circulating testosterone begins to decrease
-circulating FSH and LH increase
-sperm production continues
-sex activity decreases with decreasing testosterone levels
menstrual cycle graph again
