Chapter 19 - Reproductive System Flashcards
Gametogenesis
production of gametes
Oogenesis
gametogenesis in females; produces an ovum; takes 300 days to complete
spermatogenesis
gametogenesis in males; produces a spermatozoa; takes 74 days to complete
When does gametogenesis begin?
~5th week of embryonic development
Primordial Germ Cells (PGCs)
- migrate to genital ridges
- mitotically divide during migration and differentiate into appropriate gametogonia
Testis
- paired ovoid gonads that are housed in the pouch-like scrotum
- eachh testi is surrounded by the tunica vaginalis and tunica albuginea
tunica albuginea
projects internally to divide the testis into 200-300 distinct tubules, each containing 1-4 seminiferous tubules
seminiferous tubules are formed by:
interconnected sertoli cells
functions of seroli cells
- direct germ cell development
- scavenge cellular debris/damaged cells
- produce seminiferous fluid
- FSH-responsive
- produce inhibin
- produce androgen-binding protein (ABP)
Leydig cells
outside of seminiferous tubules; produce androgens
features of epididymis
- fluid and sperm cells travel through a series of tubules until converging into the epididyis
- lies againts the testis, coiled down to 1/2000th of its actual size
- divided into lobules; maintains tight junctions
- delivers sperm to ductus deferens, and promotes sperm fertilizing capacity
epididymis
long, thin, convoluted single duct
paired ejaculatory ducts
1-2 cm each; connect ductus deferens to urethra; mixes sperm cells with seminal plasma
Male urethra
divided into three layers:
1. prostatic urethra
2. membranous urethra
3. spongy urethra
What is the function of the male’s 3 urethra layers?
conduct semen out of the male reproductive tract during ejaculatioin
Features of the seminal vesicles
- excretory duct on each gland joins with ampulla of ductus deferens to firm ejaculatory duct
- Lumen consist of highly-convoluted irregular mucosa (increases surface area)
- surrounded by 2 layers of smooth muscle (squeezes products out during ejaculation)
Prostate gland features
- largest human accessory sex gland
- consists of many lobules that all open up into prostatic urethra
- produces ~30% of seminal plasma by volume
- secrets factors that promote sperm survival, activation and fertilization (citric acid, PSAP, zinc, prostate specific antigen, hCAP-18)
features of the bulbourethral gland
- 2 cm-long ducts join wiith spongy urethra
- secretions make up first fraction of ejaculate (5% of total)
- typically does not mix with sperm cells; sometimes called pre-ejaculate
- clear, alkaline fluid consists of lubricating prteins and neutralizing mucins
the penis
- elongated structure that grows in both girth and length during sexual arousal
3 parts of penis
- roots: attach penis to pelvic girdle
- body: contains penile urethra and corpora cavernosa
- glans: highly-sensitive bulbous structure at the end of penis
what is the primary function of the scrotum
maintains temperature of testes at 34ºC to promote spermatogenesis
Features of the scrotum
- suspended at base of pelvis; houses testes, epididymis and proximal portion of ductus deferens
- bisected at midline to create 2 compartments
- temperature monitored with thermoreceptors
- cremaster muscle
Cremaster muscle
can draw testes inward to protect them from harm when needed
Features of the ovaries
- positioned on either side of the uterus, anchored by the mesovarium
- ovarian arteries, veins, and nerves pass out of the ovary at the hilum (like a string)
- outer cortex of ovary: dense connective tissue interspersed with thousands of ovarian follicles containing developing germ cells
- inner medulla: areolar connective tissue with arteries, veins, nerves, and lymphatic vessels
Fetures of the ovarian follicle
- specialized granulosa cells develop (cumulis oosphorus) that later develop into corona radiata
- other granulosa and thecal cells will develop into luteal cells
- typically, only 1 tertiary follicle matures per cycle
corpus luteum
transient endocrine organ formed from granulosa and thecal cells
- YELLOW
- persists and secretes hormones if pregnancy occurs
- if pregnancy doesn’t happen: luteal cells degenerate and are replaced by the corpus albicans(WHITE)
- corpus albicans is resorbed after a few months
Uterine ducts
extend laterally from uterus; divided into four distinct regions:
1. infundibulum: has fimbriae that sweep oocytes into ostium
2. Ampulla:site of fertilization
3. isthmus: accounts for 1/3 of length
4. intramural segment: where isthmus enters the uterine cavity
Uterus regions
4 regions:
1. fundus: base of inverted pear shape
2. body: broad region
3. isthmus: narrow region
4. cervix: projects into vagina
function of uterus
structure of gestation (receives, retains, and nourishes fetus)
- anchored in place by several ligaments
Layers of uterus
- perimetrium: outer serosa
- myometrium: 3 layers of smooth muscle
- endometrium: site of implantation
- basal layer: permanent structure; contains arteries and acini from uterine glands
- functional layer: (regenerates every month) hormone-responsive layer; grows in presence of hormones and degenerates/sheds during menses
features of cervix
- dome-like structure of uterus that projects into vagina
- endometrium is not shed during menses, and myometrium is much thinner
- cervical canal joins uterus to vagin
- mucosa produce secretions that create a mucous plug, slowing sperm or microorgansims
functions of vagina
- copulatory organ
- passageway for outflow of menstruation
- birth canal during partuition
Layers of vagina
- outer adventitia
- middle muscularis
- inner mucosa
Vestibule lies between and is hidden by the paired:
Vestibule lies between and is hidden by the paried labia minora
Vulvar vestibule is occupied by:
Vulvar vestibule is occupied by vaginal orifice
Hymen
- connective tissue membrane
- covers vaginal orifice in pre-coital females
Ducts of ________ and ________________ also found in vestibule
Ducts of paraurethraland greater vestibular glands also found in vestibule
Clitoris
- erectile body
- partly homologous to male penis
- cylindrical shaft w/ corpora cavernosa and distal glans
- rich in pressure and temp. receptors
- vestibular bulbs found on either side of the vaginal orifice, and also engorge during sexual arousal
Describe the pathway of sex hormone release
- Hypothalamus secretes GnRH
- Anterior pituitary secretes FSH and LH
- FSH and LH reach the Gonads where they secrete sex hormones
- Sex hormones either go to do gametogenesis or they go to the reproductive tract/other organs
What regulates gametogenesis?
hypothalamic-pituitary-gonadal axis
Gametogenesis hormone pathway:
- GnRH synthesized by hypothalamic neurons
- released through hypothalamic-hypophyseal portal system
- stim. release of gonadotropins LH and FSH from anterior pituitary
- Gonadotropins enter general circulation
- stim. gametogenesis and steroidogenesis in gonads
What are the two parts of menstrual cycle?
- ovarian cycle
- uterine cycle
Ovarian cycle
- follicular phase: rapid growth of tertiary follicle in preparation for ovulation; estrogen
- luteal phase: presence of corpus luteum; progesterone
Ovulation begins around which day in a cycle?
Day 14
Uterine Cycle
- menstrual phase:characterized by menses
- proliferative phase:dominant follicle rapidly growing; estrogen-priming for endometrial repair, regeneration
- secretory phase:endometrium becomes vascularized in preparation for pregnancy (only phase in luteal phase)
During the early follicular phase, estrogen is at its:
LOWEST
During the early follicular phase, FSH levels ________ at first, stimulating:
During early follicular phase, FSH levels rise at first, stimulating follicle growth
- FSH is then downregulated by inhibin causing estrogen to RISE
During the early follicular phase, when estrogen is high, both LH and FSH:
reach a high peak
Describe the hormones during the mid-follicular phase:
- one follicle remains due to low FSH
- estrogen levels rapidly rise
- small surge in LH promotes even more estrogen
Describe the hormones during the late follicular phase and LH surge:
- estrogen levels reach their peak (LH and FSH peak)
- switches from negative to positive feedback –> LH surge
- rapid loss of estrogen
- ovulation
- corpus luteum formation
Describe the hormones during the Luteal phase
- progesterone prepares endometrium uterus for pregnancy
- LH levels decline and estrogen levels rise
- in absence of pregnancy, corpus luteum undergoes functional and structural regression
Wolffian duct
has potential to form parts of male reproductive tract
Müllerian duct
has potential to form parts of female reproductive tract
Features of male climacteric
- decreased testosterone production, leading to loss in testicular volume and sperm production
- diminished sex drive
- occasional mood swings
- erectile dysfunction/impotence
- prostate enlargement
Features of female climacteric
- drop in circulation estrogen
- ovaries are devoid of follicles and menstruation stops
- reproductive organs undergo modest atrophy; vagin lubrication is reduced
- breast tissue atrophies
- hot flashes; figure becomes more androgynous; bones become brittle
