Week 4- Endocrinology of Pregnancy Flashcards
What hormone causes tubular fluid reabsorbtion?
Oestrogen
What hormone causes secretion of nutrients & glycoproteins into epididymal fluid?
Androgens
What should you always do if you see a female of reproductive age with abdominal pain?
A pregnancy test (it may be an eptopic pregnancy)
What is ejaculated in the semen?
Spermatozoa (15/120 million per mill)
Seminal fluid (2-5 ml)
Leucocytes
Potentially viruses
What happens during capacitation of sperm?
Loss of glycoprotein coat
Change in surface membrane characteristics
Develop whiplash movements of tail
Where does capacitation of sperm occour?
Fallopian tube
What 2 molecules is capacitation dependent on?
Oestrogen and calcium
What are the 2 phases of implantation?
Attachment: outer trophoblast cells contact uterine surface epithelium
Decidualisation phase: changes in underlying uterine stromal tissue
What hormones does implantation require?
Requires progesterone domination in presence of oestrogen
What is the sperm receptor on the surface of ova called?
ZP3
What is the layer on the ova that the sperm penetrates called and what is it made of?
A glycoprotein layer called the zona pellucida
What is the reaction called when the sperm penetrates the egg?
Acrosome reaction
Describe the acrosome reaction
Sperm binds to ZP3 receptor
Ca2+ influx into the sperm stimulated by progesterone
Sperm releases hyaluronidase and proteolytic enzymes from acrosome
Spermatozoon penetrates the zona pellucida
Where does fertilisation occour?
Fallopian tubes
What reaction does fertilisation trigger?
Cortical reaction
Describe the cortical reaction and its purpose
Upon fertilisation, cortical granules release molecules that degrade the zona pellucida so there are no ZP3 receptors and further sperm cant bind
Around what day does the blastocyst implant?
Day 8-9 after fertilisation
What is the fertilized egg called as its developing before it becomes a blastocyst?
Conceptus
What are the 2 phases of implantation? Describe them
Attachement phase: outer trophoblast cells contact the uterine surface epithelium
Decidualisation phase: changes in underlying uterine stromal tissue
What hormone does implantation require?
Progesterone dominating in the presence of oestrogen
What are the 2 main chemicals involved in blastocyst attachment and what do they do?
LIF (leukemia inhibitory factor)- from endometrial cells and stimulates adhesion of blastocyst to endometrial cells
IL11 (interleukin 11)- also from endometrial cells, released into uterine fluid and aids attachment
What is decidualisation?
Endometrial changes due to progesterone including:
Glandular epithelial secretion
Glycogen accumulation in stromal cell cytoplasm
Growth of capillaries
Increased vascular permeability (could lead to oedema)
What chemicals are involved with decidualisation?
Progesterone, IL11, histamine, TGFb
Where does hCG come from?
Comes from placenta
How do hCG levels change during pregnancy?
Rise in a spike from week 0 to 10 then fall
How do progesterone levels change during pregnancy?
Rise from week 0, peak at around week 35 then fall by week 40
How do oestrogen levels change during pregnancy? How do they compare to progesterone levels?
Rise constantly throughout to peak by week 40 then fall, always lower than progesterone levels
How do human placental lactogen levels change during pregnancy? How do they compare to progesterone and oestrogen levels?
Rise throughout to peak in week 40 then drop, always lower than progesterone and oestrogen
Where are oestrogen and progesterone produced during pregnancy?
First 40 days: corpus luteum in ovary, stimulated by hCG (acts on LH receptors)
After day 40: placenta starts to take over
What is the substrate for oestrogen and progesterone?
DHEA
Why are oestrogen and progesterone important during pregnancy?
They are essential for the developing fetoplacental unit, they also inhibit maternal LH and FSH (via negative feedback)
For each of the following hormones describe wether they increase or decrease during pregnancy: Gonadotrophins Iodothyronines Prolactin PTH related peptides Pituitary gland GH TSH ACTH Adrenal steroids IGF1
Gonadotrophins- decrease Iodothyronines-increase Prolactin-increase PTH related peptides-increase Pituitary gland GH-decrease TSH-decrease ACTH-increase Adrenal steroids-increase IGF1-increase
Which hormone cannot be tested for during pregnancy if a pituitary tumor is suspected? What test is performed instead?
Prolactin- usually prolactinemia causes higher prolactin levels but women have higher levels anyway due to the preganancy
Instead a visual fields test is performed as the tumor causes bitemporal hemanopia
What is the function of PTH related peptides have during pregnancy?
Calcium mobilisation for development of fetal skeleton
Where is oxytocin released from and what does it do?
Released from the posterior pituitary gland, causes milk ejection, cervical dilatation and uterine contraction
Describe the endocrine control of lactation when the nipple is stimulated?
Afferent pathways are stimulated
Afferent signals in the hypothalamus stimulate oxytocin releasing activity and inhibit dopamine release
Reduced dopamine causes less inhibition of lactotrophs in the anterior pituitary
Plasma oxytocin and prolactin levels rise, stimulating milk ejection from mamillary glands
