pregnancy parturition and lactation Flashcards
(36 cards)
where and when is the delay for fertilization to occur?
days 1-2 after sperm deposited;
at ampullary-isthmic junction
when does egg enter uterine cavity?
and as what?
days 3-4
as a morula
when does blastocyst implant?
around day 5-7
how do steroid hormones circulate?
bound to plasma proteins , they are nonpolar/poorly soluble
little is present in free form –> free form is active/capable of entering target cells
what carries estrogen and testosterone in circulation?
what carries cortisol and progesterone?
sex hormone binding globulin (SHBG)
cortisol binding globulin (CBG)
binding capacity of cbg and shbg
how is spillover handled?
high affinity but low capacity due to low amounts of cbg and shbg
albumin can carry excess (nonspecific/low affinity but high capacity)
blood levels of cbg and shbg are highest in…
pregnant women at term (highest E level)
estrogen stimulates production of both!
urinary excretion of free hormone is a direct reflection of what?
index of the levels of ACTIVE free hormone in circulation
mechanism of steroid hormone
pass through target cell membrane and bind to cytoplasmic receptor
transfer into nucleus and bind to specific chromatin receptor
RNA transcription –> mRNA –> translation of specific proteins
two main chemical modifications to inactivate steroid hormones (in liver)
glucuronidation or sulfation - increases water solubility
reduction - inactivation
allows excretion!
3 transport functions of the cervix
- rapid transport of sperm into uterus
- colonization of sperm into cervical crypts
- slow release of sperm from crypts (delayed delivery)
how fast do sperm reach fallopian tube? does orgasm play role?
5-15 min!
NO
role of sperm motility
necessary for fertilization
but does not account for the rapid transport to the ampulla; it is the female tract fluid movement that mediates this transport
sperm capacitation
occurs in the female repro tract and results in a sperm capable of fertilizing an egg
involves the acrosome reaction! –activation of hydrolytic enzymes and the merging of sperm head and membranes
acrosome reaction
series of hydrolytic enzyme activation expose proteins on sperm head –>allows a sperm to interact with zona pellucida receptors and digest its way through the egg
fertilization is ___ mediated
requires sperm head to bind to ______
receptor;
sperm head must bind to zona pellucida with proteins exposed by acrosome reaction
penetration of the vitelline membrane by the sperm requires 2 reactions
1 - release of cortical granules into the perivitelline space (prevents polyspermy)
2-triggers final stages of meiosis in the oocyte (2nd meiotic division, 2nd polar body, and haploid number achieved)
the ____ invades the endometrial stroma
syncytiotrophoblast
the portion of the blastocyst that lies against the uterine wall is destined to become ____
the fetal placenta (trophoblastic cells)
endometrium at site of contact becomes female placenta (decidua baalis)
what transforms the endometrium in contact with blastocyst into the decidua (maternal placenta)?
progesterone from the corpus luteum
no progesterone = no implantation!
placenta =
decidua (maternal tissue) + trophoblast
autonomy of fetal tissue
after placenta is formed, there is high fetal autonomy in that the trophoblastic tissue produces gonadotropins and steroids that are adequate to maintain gestation,even in complete absence of maternal pituitary and ovarian function
hCG
glycoprotein made by the trophoblast
actions are similar to LH
roles: maintain corpus luteum progesterone secretion and stimulation of T secretion by the fetal testis
may also prevent rejection and stimulate placental steroidogenesis
earliest sign of definitive pregnancy?
presence of hCG in the plasma (6-8 days after fertilization)
hcg in urine is about 18 days after ovulation
