Reproductive System Flashcards
reproductive system
the only organ that does not contribute to homeostasis
function of gonads (testes/ovaries)
- steroid production
2. gametogenesis
steroid production
- male: testosterone
- female: estrogen/progesterone
gametogenesis
- male: sperm
- female: egg (oocyte)
mesonephric ducts
= Wolffian ducts
- develop in males, regress in females
paramesonephric ducts
= Mullerian ducts
- develop in females, regress in males
what does the hypothalamus secrete
gonadotropin releasing hormone
what does the anterior pituitary secrete
- follicle stimulating hormone
- leutinizing hormone
Wolffian ducts transformation to
- epididymis
- vas deferens
- seminal vesicles
- ejaculatory duct
Dihydrotestosterone (DHT) helps the development of
- penis
- scrotum
- prostate
absence of AMH leads to
Mullerian ducts
Mullerian ducts transformation to
- uterus
- Fallopian tubes
- inner vagina
absence of testosterone
- regression of Wolffian ducts
- development of:
- outer vagina
- female external genitalia
what is dihydrotestosterone (DTH) required for?
development of external genitalia
testicular feminization syndrome
- XY genotype
- testes develop but female external genitalia and vagina
- caused by mutation in androgen receptor gene
- raised female; detected when menstruation fails to occur
- X-linked recessive
- no ovaries, uterus, Fallopian tubes, internal vagina –> not fertile
testes contain
seminiferous tubules
testes
steroid production, spermatogenesis
seminiferous tubules contain
- interstitial (leydig) cells
- nurse (sertoli) cells
interstitial cells
- make and release androgens
- make testosterone
- LH
nurse cells
- form blood testes barrier
- –> to protect sperm from immune system
- promote sperm development
- provide nutrients / remove wastes + growth factors
- FSH
2nd meiotic division
reduce number of chromosomes
spermatogonia
present throughout life
how long does it take to build spermatozoa
about 64-72 days
- help/protection from Sertoli cells
how much sperm per day do males produce?
about 400 million sperm per day
- MUST be at 2-3˚ C below body temp
acrosome
has enzymes need to fertilize egg
head of sperm
DNA
midpiece of sperm
lots of mitochondria
—> for ATP to swim
tail of sperm
propels sperm
- about 3 mm/min
- can reach uterine tube in 30 min
how do sperm move through the male tract?
via fluid pressure
- can’t swim until in female tract
male pathway
- seminiferous tubules
- rete testis
- efferent ductus
- epididymis
- ductus (vas) deferens
- ejaculatory duct
- urethra
seminiferous tubules
spermatogenesis occurs here
epididymis
sperm complete maturation here
accessory glands
- seminal vesicles
- prostate
- bulbourethral glands
accessory glands production
semen
- 10% sperm + secretions from glands
seminal vesicles
- 60%
- alkaline mucus
- fructose
- prostaglandins (contract uterus)
- proseminogelin
prostate
- 30%
- alkaline mcus
- clotting enzymes
- proteases
bulbourethral glands
- trace amount
- clear slippery fluid
- neutralizes acidity of residual urine is urethra
- lubricates head of penis
FSH
- activates sertoli cells
- which tumult spermatogenesis
- also cause inhibin
- only negative feedback to anterior pituitary
LH
- activates leydig cells
- produces testosterone
- double negative feedback loop
inhibin
allows regulation of spermatiogenesis without decrease in testosterone (decrease FSH only not LH)
3-6 month testosterone secretion
for development of ducts and external genitalia
age 1-10 years old
no FHS/LH in blood before puberty
puberty
increased GnRH
functions of testicular androgens
- development/growth/maintenacne of repro tract/glands
- spermatogenesis
- body growth: esp. bone, muscle, vocal cords
- pubic/axillary/facial hair (back, ear, nostril)
- increased thickness of skin, basal metabolic rate, red blood cells
- libido/aggressive behavior
male erection
- decrease activity of sympathetic neurons
- PSNS
- increase nitric oxide
- activates GC
- increase cGMP
- relax arterial smooth muscle (vasodilation)
- –> dilation of arteries
- erection
- compression of veins (maintains erection)
erection is stopped by
- decreased PSNS
= increased PDES enzyme - cGMP —> 5’GMP
= vasoconstriction
viagra/cialis
block PDES = maintain cGMP = maintains erection
orgasm - emission stage
- vas deferens exhibits peristalsis
- sperm moved into ampulla, ampulla contracts, sperm moved into urethra
- prostate secretes components of the seminal fluid
- seminal vesicles secrete components of the seminal fluid
orgasm - expulsion stage
- prostate releases additional secretion
- seminal vesicles release additional secretion
- internal urethral sphincter contraction; urine is retained in bladder
- bulbocanvernosus muscle contracts and compresses build and root of penis; semen is expelled
resolution
- internal pudendal arterial constricts
- reduces blood flow into penis
- trabecular muscle contract
- squeeze blood from erectile tissues
- penis becomes flaccid
ejaculation
emission + explusion
male refractory period
10 min - several hours
female refractory period
none
ovaries
oogenesis and production of estrogen and progesterone
oogenesis
each egg develop in its own follicle
Fallopian tube parts
- infundibulum
- ampulla
- isthmus
uterus parts
- endometrium
- myometrium
- cervix
endometrium
epithelial living that responds to hormones
myometrium
muscle layer
cervix
portion of uterus that protrudes into vaginal canal
secondary oocyte
just prior to ovulation, the primary oocyte completes the first meiotic division
ovum
sperm entry into the secondary oocyte triggers the 2nd meiotic division
theca cells
produce androgens
granulosa cells
convert androgens to estrogens
antrum
fluid filled sacks that stores estrogen
corpus luteum
after ovulation old granulosa/theca cells form this
corpus luteum cells:
- cells hypertrophy
- secrete estrogen and lots of progesterone
- storage site for cholesterol
- becomes vascularized
what happens to the corpus luteum if there is no fertilization?
corpus luteum degenerates and forms corpus albicans (scar tissue)
ovarian cycle
- follicular phase
- luteal phase
uterine cycle
- menstrual phase
- proliferative phase
- secretory phase
- pre-menstrual phase
what drives the ovarian cycle?
anterior pituitary hormones
what drives the uterine cycle?
ovarian hormones
follicular phase
- days 1-14
- FHS stimulates several follicles to grow
- mature follicle secretes lots of estrogen (at day 14)
ovulation
- day 14
- rupture of mature follicle and release of egg
- increase estrogen tells anterior pituitary follicle is ready = increase LH = causes ovulation
Positive feedback: LH/FSH “surge”
- primary oocyte becomes secondary oocyte
- ovulation
- follicle transformed into corpus luteum
luteal phase
- 15-28 days (ALWAYS 14 days)
- goal = prepare uterus for pregnancy
- corpus luteum secretes lot of progesterone and estrogen
- degenerates at about day 24 if no fertilization
menstrual phase
- days 1-5
- endometrium sloughs off and exits body
- about 50-70 mL
proliferative phase
- days 5-14
- estrogen from growing follicles stimulates growth of endometrium (0.5 mm –> 2-3 mm thick)
secretory phase
- days 15-26
- progesterone stimulates endometrium to secrete glycogen
- estrogen stimulates continued growth (5-6 mm thick)
- rich in blood vessels / nutrients
premenstrual phase
- days 27-28
- decreased estrogen and progesterone (corpus luteum dead)
- vasoconstriction, endometrium dies
follicle
estrogen: increase development
progesterone: decrease development
cilia/fimbriae
estrogen: increase activity
progesterone: decrease activity
endometrium
estrogen: proliferation
progesterone: secretory
myometrium
estrogen: increase growth, contractility (propel sperm into uterine tube)
progesterone: decrease contractility (facilitate implantation; prevent pre-mature delivery)
cervical mucus
estrogen: thin, watery, lots (for easy movement of sperm
progesterone: viscous, little (mucus plug during pregnancy)
breast
estrogen: growth/duct dev./fat
progestogen: glandular growth
estrogen at puberty
- bone growth
- development of breasts, genitalia
- pelvic widening
- female fat distribution (breasts, hips, subcutaneous)
estrogen other roles
- osteoblast activation (build bone)
- permissive of vasoconstriction
- increase basal metabolic rate
- smooth/soft skin, more vascularized
fertilization occurs at:
distal end of uterine tube
fertilization
- egg lives about 24 hours after ovulation and takes about 4 days to travel to uterus
- only about 200 sperm reach the egg
- capacition takes 10 hours –> enzymes in acrosome are activated (plasma membrane sheds cholesterol)
trying to conceive?
sex 3-6 days before ovulation –> up to 14 hours after ovulation
Y-bearing sperm
light-weight, fast
- increased probability of boy when have sex after ovulation
- Y gets to egg first
X-bearing sperm
heavy, slow
- increased probability of girl when have sex before ovulation
hCG
- secreted by blastocyst/placenta
- rescues corpus luteum (LH-like) to keep estrogen and progesterone levels high
- basis for pregnancy tests
estrogen
- secreted by corpus luteum (early), then placenta
- stimulates tissue growth in mother (uterus) and fetus
progesterone
- secreted by corpus luteum (early), then placenta
- prevents ovulation, menstruation, and uterine contractions
when is the placenta developed?
3 months
trophoblast
becomes placenta
- secretes hCG
inner cell mass
becomes embryo
fully embedded after 2 weeks
- gastrula
development of 3 germ layers:
- ectoderm
- mesoderm
- endoderm
day 16 term
embryo
organogenesis
germ layers differentiate into organs
- during embryo stage
ectoderm
- epithelia
- epidermis
- hair
- nervous tissue
mesoderm
- bone
- cartilage
- muscle
- blood
endoderm
- GI
- respiratory tracts
- thyroid
- bladder
fetus
at week 8 all organs systems present
placenta
- attached to endometrium and to fetus by umbilical cord
- nutrients/wastes diffuse between mother and fetus (no mixing of blood)
- secretes hCG (early), estrogen, progesterone, inhibin
trophoblastic phase
nutrients from the endometrium
placental phase
only source after week 12
stages of labor
- dilation
- expulsion
- placental
labor
partuition
dilation
- longest
- cervix widens
- “water breaks”
- 10 cm = fully dilated
expulsion
- delivery
- baby head in vagina
placental
placenta (‘afterbirth’ expelled by uterine contractions
suckling - decrease in dopamine
- decrease in dopamine in hypothalamus
- increase in prolactin in anterior pituitary
- increase milk synthesis for next feeding
suckling - increase oxytocin
- increase oxytocin in posterior pituitary
- milk ejection for current feeding
