Exam 4 Lesson 24 Pregnancy Hormones Flashcards
What cells work cooperatively during follicular and luteal phases to produce hormones?
Granulosa and theca cells
What gonadotropin stimulates granulosa cells during follicular phase?
FSH
What gonadotropin stimulates theca cells during follicular phase?
LH
During follicular phase, how is cholesterol used?
Cholesterol is turned to an androgen with aromatase activity. Then androgen from theca cell is sent to granulosa cell to make estrogen.
What stimulates granulosa cells in luteal phase?
LH and FSH
What stimulates theca cells during luteal phase?
LH
How is cholesterol used during luteal phase?
Theca lutein cells turn cholesterol into progesterone. Progesterone is then used by granulosa cell to make estrogen with FSH.
During luteal phase, what role does LH play in granulosa cells?
LH turns cholesterol into progesterone
During follicular phase, what androgenic steroids are produced in theca cell with help of LH?
dehydroepiandrosterone (DHA), androstenedione, and testosterone
What three follicles, in order, exist in follicular phase?
Primordial follicles, primary/secondary follicles, and graafian foliicle
What is the first thing that happens during follicular phase?
FSH stimulates the maturation of several primordial follicles
What happens after FSH stimulates maturation of primordial follicles in follicular phase?
Granulosa cells proliferate and secrete estrogen under FSH stimulation.
What happens after granulosa cells secrete estrogen during follicular phase?
Granulosa cells acquire LH receptors as the initial strep toward luteinization.
What is the overall main event during the follicular phase?
Synthesis of estrogen
What happens in between follicular and luteal phases?
Ovulation
What is main event during luteal phase?
Synthesis of progesterone and estrogen
What first happens during luteal phase after ovulation?
Persistent LH stimulation induces luteinization of residual granulosa cells and theca internal cells
What happens after luteinization of granulosa and theca cells during luteal phase?
In the absence of fertilization, FSH and LH secretion declines and the corpus luteum regresses (luteolysis)
What is main body during luteal phase?
Corpus luteum
What hormones drop during luteal phase?
LH and FSH. Progesterone really rises during luteal phase and then plateaus, which estradiol decreases but then experiences a rise towards end of cycle
Theca interna-follicular cell synergism
LH stimulates the production by theca internal cells of androstenedione, which is translated to granules cells for its aromatization.
What stimulates synthesis of LH receptor by g. cells ilaste in follicular phase?
Estrogen and FSH
How do progesterone and estrogen secretion change in response to LH stimulation?
Progesterone and estrogen secretion from rapidly luteinizing follicle increases
What happens if pregnancy does not occur 7 days after ovulation?
luteolysis. The production of progesterone, estrogen and inhibit decreases and FSH levels increase gradually. Menstruation begins.
What are the two phases of the endometrial cycle?
proliferative and secretory
Three stages of proliferative phase
Early proliferative period, midproliferative period and late proliferative period
What happens during early proliferative period?
The glands are short, straight, and narrow. The lamina propria is compacted. First five days include menstrual cycle.
What happens during midproliferative period?
The glands are longer and straight. The epithelium is mitotically active. The lamina propria is slightly edematous.
what happens during the late proliferative period?
Mitosis activity is intense. The glands grow rapidly and become tortuous. The lamina propria is more edematous.
What happens after proliferative phase?
ovulation
Three stages of secretory phase
midsecretory period, final days of cycle, ischemic period
midsecretory period
Glycogen accumulates in the basal portion of the glandular epithelial cells. The glands have a saw-toothed appearance. The cells of the stromal surrounding the spiral arteries enlarge and become decidual-like.
Final days of the cycle
Glycogen shifts to the apical portion of the glandular epithelium. The glands have secretion in the lumen. The stromal cells surrounding the spiral arteries are mitotically active, an indication of a residual.
Ischemic period
Upper region of the endometrial stromal contains numerous residual cells. The spiral arteries contract and ischemic starts.
How does estrogen affect ovary and follicles?
Stimulates their growth
How does estrogen affect smooth muscle and epithelial linings of reproductive tract?
A. stimulates growth of smooth muscle
b. stimulates proliferation of epithelial linings of rep tract
How does estrogen affect fallopian tubes, uterus, and vagina?
Fallopian tubes: increases contractions and ciliary activity
Uterus: increases myometrial contractions and responsiveness to oxytocin. Stimulates secretion of abundant, fluid cervical mucus. Prepares endometrium for progesterone’s actions by inducing progesterone receptors.
Vagina - increases layering of epithelial cells
How does estrogen affect genitalia growth?
Stimulates external genitalia growth, esp. During puberty.
How does estrogen affect breast growth?
Stimulates breast growth, particularly ducts and fat deposition during puberty.
How does estrogen affect female body configuration?
Stimulates female body configuration development during puberty: narrow shoulders, broad hips, female fat distribution (hips and breasts)
How does estrogen affect skin glands?
Stimulates a more fluid secretion from lipid (sebum) producing skin glands. antiacne effect.
How does estrogen affect bone growth?
Stimulates bone growth and ultimate cessation of bone growth (closure of epiphyseal plates); protects against osteoporosis, does not have an anabolic effect on skeletal muscle
Estrogen effects on vascular system?
Deficiency produces “hot flashes”
How does estrogen affect prolactin production?
Stimulates prolactin secretion but inhibits prolactin’s milk-inducing action on the breasts
How does estrogen protect against atherosclerosis?
Effects on plasma cholesterol, blood vessels, and blood clotting
How does progesterone affect endometrium?
Converts the estrogen-primed endometrium to an actively secreting tissue suitable for implantation of an embryo
How does progesterone affect cervix?
Induces thick, sticky cervical mucus
How does progesterone affect fallopian tubes and myometrium?
It decreases contractions of fallopian tubes and myometrium.
How does progesterone affect vaginal epithelial cells.
Decreases their proliferation
How does progesterone affect breast growth?
Stimulates breast growth, particularly glandular tissue.
How does progesterone affect prolactin?
Inhibits milk-inducing effects
How does progesterone affect hypothalamus and anterior pituitary?
It has feedback effects.
How does progesterone affect body temperature?
It increases it.
How many sperm are deposited in vagina? How may reach uterine cavity? How many arrive at distal end of fallopian tuber?
250,000,000/ 100,000/ 50 or less
Where does fertilization occur? What kind of delay is there?
ampullary-isthmic junction/ Days 1-2
How long is delay at utero-tubal junction?
Days 2-3
When does egg enter uterine cavity as a Modula?
Days 3-4
When does blastocyst implant?
Day 7
Steps in process of fertilization of human egg (5)
- Zona pellucida (15-25 min)
- Perivitelline Space (less than one sec)
- Perivitelline Membrane (less than one min)
A. release of cortical granules
B. completion of second melodic division and formation of polar body - Male and female pronuclei visible (2-3 hours)
- Mitosis spindle and first cleavage (24 hours)
What are ovulate eggs surrounded by?
Small cumulus cells embedded in extracellular material that consists mainly of hyaluronic acid. Cumulus layer is separate from the egg by the zona pellucida, which is made up of pellucida proteins
What changes occur to spermatozoa required for fertilization?
A. phosphorylation of various proteins
b. activation of PKA and PKC, removal of cholesterol from the membrane
c. elevation of intracellular Ca2+ level
Sperm undergo acrosome reaction. What is acrosome reaction?
Various enzymes and proteins are released from the acrosome. Only acrosome-reacted spermatozoa can penetrate and fuse with eggs. The acrosomal vehicle is surrounded by outer acrosome membrane and inner acrosome membrane. The acrosome contains both instantly and slowly released proteins and its contents are exocytosed during the acrosome reaction in which the sperm plasma membrane and OAM fuse in multiple places within the acrosomal cap area.
indicator of completion of spermatozoa capacitation
phospholipase C and SNARE proteins
hyperactivation
Vigorous swimming pattern of spermatozoa. Involves CatSper ion channels.
Where do sperm display acrosome reaction?
close to corona radiata
hyaluronidase
Released from the acrosome dissolves the intercellular material present between cells of the corona radiate.
What is proacrosin
The inactive precursor of acrosin
ZP3
The first sperm to reach the zona pellucida binds to ZP3, one of the zone’s three glycoprotein components. Binding to ZP3 causes release of acrosin from inner acrosomal membrane.
Role of acrosin
Facilitates penetration of the zonal by the sperm head
What does first sperm to penetrate zona pellucida do?
Fuses with the ovum’s plasma membrane and induces Ca2+ dependent exocytosis of cortical granules located just beneath the plasma membrane.
What do cortical granules from zona pellucida do?
Remove carbohydrates from ZP3 and partially cleave ZP2 to block binding of additional sperm.
What is disintegrin?
Cell surface molecule that induces plasma membrane fusion. Have a protease domain that dissolves the plasma membrane of the egg.
When is second polar body released?
After fertilization
What proteins mediate binding of sperm to egg?
Izumo1 and Juno
Izumo1
Tethered to membrane of sperm, forms an adhesion complex with its receptor protein, Juno, whi8ch spans the egg’s membrane. This adhesion complex is needed for fertilization.
What happens to Juno after fertilization?
It is lost from the egg’s membrane, exiting in extracellular vehicles, thereby preventing the binding and fusion of additional sperm, known as block to polyspermy
Three steps of fertilization
Acrosome reaction, ZP3 binding, sperm-egg fusion
Steps to blastocyst attachment
- At site of apposition, uterine endometrial cells express heparin-binding EGF-like growth factor (HB-EGF) with binding affinity to heparin sulfate proteoglycans and EGF receptor (EGF-R) on the surface of the trophectoderm.
- Binding of membrane-anchored or soluble HB-EGF to EGF-R induces receptor autophosphorylation.
- Apical domain of uterine epithelial cells contains microprocesses, the pinopodes, interacting with microvilli on the apical surface of trophoectodermic cells.
pinopodes
microprocesses in apical domain of epithelial cells that interact with microvilli on the apical surface of trophoectodermic cells.
Primary decidual zone
Develops when decidual cells become epithelial-like and proliferate. Fibronectin, laminin, enacting, and types I, III, IV, and V collagen are components of the primary decidual zone.
What is observed at blastocyst implantation site?
Localized vascular permeability
What happens to trophectodermic cells during implantation?
Processes of trophectodermic cells penetrate between uterine Lumina cells that under apoptosis
What facilitates embryo penetration?
A reduction in the number of desmosomes
What happens to primary decidual zone?
It is replaced by a secondary decidual zone.
What regulates the remodeling of the decidual zone?
Matrix metalloproteinase (MMPs), tissue inhibitors of MMPs (TIMPs), plasminogen activators (PAs(), and inhibitors regulate the remodeling of the residual zone in the pretense of prostaglandin 2.
Organization of placenta.
Two sides. Umbilical side has umbilical artery and umbilical vein. Endometrial side has endometrial vein and endometrial artery. The chronic plate houses the umbilical artery and vein and the chorionic villi. Each chorionic villus has arterial flow into it and venal flow out of it. Each branch of the villus is a syncytiotrophoblast. Between the chronic plate and the endometrium is what is called intervillous space.
decidua basalis
Other name for endometrium
Functions of placenta
A. receptor mediated endocytosis of maternal immunoglobulin
b. ATP-dependent membrane channels facility the active transport of ions
c. facilitated diffusion of glucose
d. gas exchange by simple diffusion
Role of placental lactogen
Together with chorionic gonadotropin, stimulate the mammary gland for postpartum lactogenesis
Role of chorionic gonadotropin
Maintains corpus luteum of pregnancy after LH secretion stops. This event is know as luteal-placental shift.
Can placenta synthesize estrogens from progesterone?
no
Can fetal adrenal cortex synthesize progesterone
no
How does placenta produce androgens?
The placenta produces progesterone that is converted by the fetal adrenal cortex to androgens (mainly dehydroepiandrosterone) and DHEA sulfate and cortisol. DHEA and DHEAS are used by placenta to form estrogens.
fetoplacental unit
Placenta-adrenal cortex cooperation in synthesis of androgens
Steroid production cycle of fetoplacental unit
Placenta produces cholesterol. At week 9, cholesterol becomes pregnenolone, which both goes to fetus and is converted to progesterone to go to maternal circulation.
In fetus, pregnenolone is converted to DHEA. DHEA goes to placenta. Becomes androstenedione, which becomes oestrone. Oestrone both goes to maternal circulation and becomes estradiol, which also goes to maternal circulation. In fetus DHEA becomes DHEAS, which becomes 16-hydroxy-DHEASS, which moves to placenta. At week 12, becomes oestriol, which goes to maternal circulation.
What hormone is necessary to maintain pregnancy?
progesterone
hCG levels during gestation
Peak between 8 to ten weeks, then decrease and plateau.
hPL (human placental lactogen) levels during gestation
start low at ten weeks, rise consistently and peak at 40 weeks.
What is the first marker of trophoblast differentiation?
hCG
What is the first measurable product of the placenta?
hCG
What is hCG?
A glycoprotein consisting of 237 amino acids. Similar in structure to the pituitary glycoprotein hormones.
What is alpha chain of hCG identical to in sequence?
The alpha chains of TSH, FSH, and LH
What is beta chain of hCG similar to?
Has 67% sequence homology with LH and an additional 30 amino acids not found in LH beta.
Plasma life of hCG? What does it allow?
24 hours.
It allows the tiny mass of cells comprising the blastocyst to produce sufficient hormone to be detected in the peripheral circulation within 24 hours of implantation. Pregnancy can thus be diagnosed several days before symptoms occur or a menstrual period has been missed.
What does HPL contribute to?
Altered maternal glucose metabolism and mobilization of free fatty acids. It causes a hyperinsulinemic response to glucose loads.
What does HPL directly stimulate?
Pancreatic islet insulin secretion. It contributes to the peripheral insulin resistance characteristic of pregnancy.
How does placenta respond to pregnancy?
Secretion of estrogen, progesterone, hCG, inhibit, HPL, and other hormones.
Anterior pituitary response to pregnancy
Increased secretion of prolactin. Secretes very little LH and FSH.
Adrenal cortex response to pregnancy
Increased secretion of aldosterone
Posterior pituitary response to pregnancy
Increased secretion of vasopressin
Parathyroid response to pregnancy
Increased secretion of PTH
Kidneys and pregnancy
Increased secretion of renin, erythropoietin, and 1,25-dihydroxyviugtamin D. Retention of salt and water. This is caused by increased aldosterone, vasopressin and estrogen.
Breasts and pregnancy
Enlarge and develop mature glandular structure. cause : estrogen, progesterone, prolactin and HPL
Blood volume and pregnancy
Increased. Cause: total erythrocyte volume is increased by erythropoietin, and plasma volume by salt and water retention. However, plasma volume usually increases more than red cells, thereby leading to small decreases in hematocrit.
Bone turnover and pregnancy
Increased. Cause: increased PTH and 1,25-dihydroxyvitamin D
Body weight and pregnancy
Increased by average of 12.5 kg, 60 percent of which is water.
Circulation and pregnancy
Cardiac output increases, total peripheral resistance decreases (vasodilator in uterus, skin, breasts, GI tract, and kidneys( and mean arterial pressure stays constant
Respiration and pregnancy
Hyperventilation occurs (arterial Pco2 decreases) due to the effects of increased progesterone
Organic metabolism and pregnancy
Metabolic rate increases. Plasma glucose, gluconeogenesis, and fatty acid mobilization all increase. Cause: hyporesponsiveness to insulin due to insulin antagonism by HPL and cortisol.
Appetite/thirst and pregnancy
Increased (particularly after the first trimester)
Nutritional RDAs and pregnancy
increased
Endocrine factors involved in initiation of parturition
A. maturation of fetal adrenal cortex
b. rise in cortisol levels
c. placental steroidogenesis
d. progesterone decreases and estrogen increases
e. estrogen unregulated myometrium and stimulates PGF 2alpha (from placenta)
f. PGF2alpha unregulated myometrium
g. myometrium unregulated oxytocin and oxytocin unregulated myometrium
How uterine contractions work?
A. posterior pituitary sends oxytocin to uterus, which results in contraction.
b. uterine contraction results in cervical stretch by pushing baby’s head downward.
c. uterine contraction unregulated itself with prostaglandins
d. cervical stretch unregulates release of oxytocin by posterior pituitary and unregulated uterine contractions
Stages of mammary gland development
A. estrogen –> amphiregulin –> ductal elongation
b. progesterone –> Went-4 and RANKL –> sidebranching
c. prolactin –> IGF-2 and cycling D1 –> alveologenesis
d. milk secretion
