Endocrinology Of Pregnancy (Part 1)

summary of contents of the lecture: what are the 3 main stages during pre-implantation? 1. follicular phase 2. luteal phase 3. implantation window after the egg is released from the ovaries, where does it go? egg travels through the cervix and implants in the endometrium •embryo continues to divide as it travels a) roughly a week after fertilisation as the embryo travels down the uterus, what does it do? a) how long after fertilisation does the embryo implant into the endometrium? •proliferates and regrows to give the endometrium (site of implantation) using the diagram, explain what B does in order for implantation to occur: in the follicular phase, what is the main hormone involved? oestrogen proliferation of the endometrial stroma what is the desired outcome of the follicular phase? in the luteal phase, what is the main hormone involved? 1/5 progesterone progesterone makes endometrium glandular and secretory •aids in decidualisation = preparing the endometrium for pregnancy what roles does progesterone have in the luteal phase [aiding implantation] ? histiotrophic nutrition how does the embryo gain nutrition during the first trimester? haemotrophic (i.e. through the placenta) in the second trimester, how does the embryo gain nutrition? what is histotroph? nutrient rich solution produced by the endometrial glands in the uterus during days 20-24 of the menstrual cycle and it is a week after fertilisation has occurred what is the implantation window? what does oestrogen stimulate during the implantation window? release of glandular secretions 2/5 what is the isthmic sphincter? muscle that generates a tight gap that separates the uterus from the Fallopian tube how can the isthmic sphincter be relaxed? ^ progesterone relative to oesterogen levels relaxes the isthmic sphincter •facilitate embryo passing through and implanting amongst other many roles, what does progesterone do to muscles? progesterone is a muscle relaxant (hence why it can relax the ishtmic sphincter) •synctiotrophoblast cells (green in the diagram) begin to secrete hCG •hCG signals that corpus luteum needs to stay one week after fertilisation, what cells 'invade' the implanting embryo? what is the role of these cells? when timing pregnancy, what do we count as day 0? the day of the last menstrual period when do levels of hCG begin to fall? from week 8 onwards although hCG levels fall, hCG is still prewhy do pregnancy tests work even after sent and the concentration is above the hCG levels have fallen? detectable value for pregnancy tests a biochemical pregnancy is when hCG is present in urine or blood, whereas a distinguish between a biochemical pregclinical pregnancy is when an ultrasound nancy and a clinical pregnancy: is carried out to observe the growing embryo what drug can be used as an anti-progesterone? mifepristone •this drug results in an abortion what cells produce progesterone? what is progesterone derived from? •synctiotrophoblast cells produce it •derived from cholesterol (steroid hormone) an ovariectomy will result in no pregnan- no corpus luteum (which produces progcy because.... esterone) 3/5 •slight dip as placenta is establishing, taking over role of corpus luteum at ~ explain why there is a dip in the graph for week 6 progesterone: oestriol during pregnancy, what is the major oesterogen circulating? what is oestrogen produced by during pregnancy? placenta + foetus 1. progesterone is produced by the placenta 2. conjugated with sulphate 3. transferred to foetus 4. fetal adrenal gland converts progeshow do we go from progesterone in the terone to androgen placenta > oestrogen in the placenta? 5. androgen is transported to the placenta 6. androgen is deconjugated (aromatised) and converted to oestrogen •makes hormone water-soluble, aiding in transport what are the 2 reasons why conjugation •renders hormone inactive so foetus is of progesterone occurs? not exposed to high levels of sex hormones what does hPL stand for? human placental lactogen when levels of hCG begin to fall when do levels of hPL rise? what is the function of hPL? acts as an anti-insulin •decrease insulin sensitivity which ^^^ maternal blood glucose >> provides glucose for foetus 4/5 •increases lipolysis > ^FFA > more of it is converted to glucose which can be what effect does hPL have on lipolysis? used by mother •keeps maternal blood glucose high *gluconeogenesis conversion of FFAs to ketones, which during times of starvation/fasting/ stress can enter the respiration pathway and be in the pregnant mother, what effects used to provide ATP does hPL have? •ATP can travel across placenta and be used by the foetus when do prolactin levels rise? linearly during pregnancy does not really have effects during pregwhat are the effects of prolactin during nancy since prolactin is linked to lactapregnancy? tion (which occurs post-pregnancy) why doesn't milk production occur during other sex hormones suppress the effects pregnancy? of prolactin what are the two main sites of prolactin release? •lactroph cells (of the anterior pituitary gland) •decidua what sex hormone stimulates prolactin release? oestrogen what is the decidua? the endometrium during pregnancy •prolactin is released into the amniotic fluid 5/5