Pregnancy/Parturition/Lactation Flashcards
When sperm bind to the Zona Pellucida what occurs?
Acrosomal reaction–Ca dependent process leads to fusion of acrosome with sperm cell plasma membrane
–hydrolytic enzymes penetrate the zone pellucida–sperm and oocyte fuse
What is the cortical reaction?
prevents entry of other sperm through a Ca/IP3 dependent process
How many days btwn fertilization and implantation?
about 6 days
In early stages of pregnancy what produces steroid hormones to maintain pregnancy until the placenta develops?
Corpus luteum
What is produced by the blastocyst in early pregnancy and why?
Human chorionic gonadotropin (hCG)–closely related to LH and sustains the corpus luteum until the placenta can take over steroid production
What is the effect of elevated progesterone throughout pregnancy and what happens to its level at the end of pregnancy?
Progesterone is high throughout pregnancy to prevent uterine contraction and spontaneous abortion
at the end of pregnancy progesterone levels drop and estrogen takes over causing uterine contractions and labor.
How does the early fetus receive nutrition until the placenta can take over?
from the endometrial decidua
What are the key hormones produced by the placenta?
Steroid hormones–progesterone/estrone/estradiol/estriol
hCG
Somatomammotrpins—support fetal metabolism and promote mammary gland development in the pregnant mother
What three enzymes are lacking in the placenta and what does this effect the production of? and how does the mother get these enzymes to produce the hormones?
17-a-hydroxylase and 17,20-desmolase–needed for synthesis of estrone and estradiol
16-a-hydroxylase–needed for synthesis of estriol
Gets from fetus–adrenal gland and liver
What 2 enzymes are lacking from the fetus and what does this effect the production of? why doesn’t the fetus have these enzymes
3-B-hydroxysteroid dehydrogenase– needed for Progesterone/androstenedione/testosterone production
aromatase– needed for all of the estrogen production for androstenedione/testosterone16-a-hydroxy-a/t
all used to convert to final estrogen products which would be dangerous for the fetus–only the mother needs the estrogens
What are the maternal responses to pregnancy?
- -Increased blood volume
- -Decreased MAP during mid pregnancy then rises to normal during 3rd trimester
- -Increased CO
- -Increased alveolar ventilation–mild alkalosis
- -increased demand for dietary protein–also iron and folic acid need for increased production of blood cells
- -uterus and breast increase in size
- -weight gain
- -BMR increases 15%
What initiates contractions and what sustains them?
initiated by prostaglandins
sustained by oxytocin and more postaglandins
How does estrogen play a role with oxytocin during pregnancy?
Increases the number of oxytocin receptors on myometrial tissue in the uterus–80-fold @ 36 wks
What do estrogen and progesterone do to milk release?
Inhibit milk release during pregnancy—when placenta is delivered= no more estrogen or progesterone to inhibit–prolactin can do its job
What is the functional secretory unit of the breast?
alveolus–organized into lobules that drain into a ductule
