Module 3 Flashcards
organogenesis is complete by Week __
8
pregnancy hormone that stimulates the corpeus luteum to continue to function
HcG
placenta is at full thickness at Week ___
16
teratogen reaction differs between fetuses due to:
differences of host susceptibility
FDA category that includes drugs that have negative effects on animals but no apparent negative effect on humans
Cat C
ovum survives for ____ hours
24
sperm survives for ____ hours
48
what is the “hatching of the blastocyst” in implantation
loss of the zona pellucida
How many days after fertilization does the loss of the zona pellucida occur?
5 days
after the loss of the zona pellucida, this occurs to from the trophoblast cell mass
rapid proliferation of the trophectoderm
What causes the blastocyst to be able to attach to the uterus?
loss of the zona pellucida
adherence of the blastocyst to the endometrial surface leads to:
the decidual reaction
erosion of the epithelium of the endometrial surface allows for the blastocyst to:
burrow beneath the surface
Steps of Implantation:
- Loss of zona pellucida
- Rapid proliferation of the trophectoderm to form the trophoblast cell mass
- Blastocyst attaches to uterus
- Blastocyst adheres to endometrial surface
- Decidual reaction
- Erosion endometrial surface erosion
- Blastocyst burrows beneath the surface
endometrial changes during pregnancy that alter the endometrial lining (“decidua”)
decidual reaction
covers growing embryo and regresses as the chorion grows. Disappears as the embryo fills the lumen of the uterus
decidua capsularis
spongy vascular bed on which the blastocyst rests. The site of the future placenta. Forms maternal portion of placenta. Where the interface between the mom and trophoblast is- changes happen here to support adhesion and migration.
decidua basalis
the remaining decidua. Fuses with the amnion and chorion at 18-20 weeks and the uterine cavity is obliterated.
decidua parietalis
Attaches to endometrium 5-6 days after fertilization, fully implanted by day 10-12
Functions to:
Erode maternal tissue to make space for implantation and growth
Secrete hormones
Transport nutrients and waste products
Placental attachment
Migration and arterial transformation
Trophoblast
layers of trophoblast differentiate on Day __
7
the mononuclear inner layer of the trophoblast that forms new syncytial cells, chorionic villi, amnion and generates new trophoblast cells
cytotrophoblast
the thick multicellular mass w/o distinct cell boundaries outerlayer of the trophoblast that invades the endometrial epithelium engulfing uterine cells and produces hCG, estrogen, progesterone, and hPL
synctiotrophoblast
what is the process that may cause implantation bleeding?
differentiation of the trophoblast
Implantation is complete on days ___-___
10-12
amniotic cavity appears during Week __
2
collapsed dominant follicle walls after ovulation that change to turn into this
corpus luteum
14-day phase of menstrual cycle that begins w/ ovulation and ends w/ cycle start
luteal phase
the progesterone factory of the luteal phase
corpus luteum
the progesterone in the corpus luteum suppresses:
the growth of new follicles
hormone that causes an elevation in basal body temperature
progesterone
if conception does not occur, the _____________ rapidly regresses 9-11 days after ovulation
corpus luteum
declining corpus luteum decreases progesterone levels which causes:
menstruation
\_\_\_\_\_\_\_\_ becomes: digestive system liver pancreas inner layer of lungs
endoderm
\_\_\_\_\_\_\_\_ becomes: circulatory system lungs (epithelial layers) skeletal system muscular system
mesoderm
\_\_\_\_\_\_\_\_\_ becomes: hair nails skin nervous system
ectoderm
period of gestation from conception to Week 2
pre-embryonic
period of gestation from Week 2-8
embryonic
period of gestation from Week 8 to Full Term
fetal
creation of new types of substances, cells, tissues, and organs that weren’t there before
differentiation
process by which these elements are coordinated into functional integrated units
organization
production of a special form, shape or structure of a group of cells and occurs by organization of groups of cells in to organs.
morphogenesis
embryonic alteration in morphogenesis due to an intrinsically abnormal developmental process such as may occur with a chromosome or multifactorial disorder.
malformation
defects are the abnormal form, shape, or position of a body part arising from extrinsic mechanical forces (e.g., clubfoot due to fetal restraint or lung hypoplasia with congenital diaphragmatic hernia)
deformation
caused by an external force that alters a previously normal tissue (e.g., teratogenic effects or amputation of a fetal part by an amniotic band)
disruption
Adequate and well-controlled human studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy (and there is no evidence of risk in later trimesters)
Category A
Animal reproduction studies have failed to demonstrate a risk to the fetus, and there are no adequate and well-controlled studies in pregnant women; or animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus in any trimester.
Category B
Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Category C
There is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.
Category D
Studies in animals or humans have demonstrated fetal abnormalities and/ or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in the use of the drug in pregnant women clearly outweigh potential benefits.
Category X
the basis of heritable developmental defects and is the result of a change in the sequence of nucleotides.
Gene Mutations
when an embryo is not susceptible to teratogenesis
Weeks 1 and 2 (The pre-embryonic period also known as the “All or Nothing” period)
agents, such as tobacco, exert effects on growth or fetal development in the second and third trimesters
fetotoxic agents
MOA of teratogen
interfere with organogenesis during the embryonic period, which results in birth defects such as a cleft palate, cardiac anomaly, facial abnormality, or another dysmorphic effect.
Four major hormones synthesized by the placenta
ahCG, hPL, progesterone, and estrogens
Maintains the corpus luteum during early pregnancy in order to ensure secretion of progesterone and other substances until placental production is adequate.
May stimulate the fetal testes and adrenal gland to enhance testosterone and corticosteroid secretion, stimulate production of placental progesterone, promote angiogenesis, uterine growth and quiescence, enhance fetal growth and development, and suppress maternal lymphocyte responses to prevent rejection of the placenta by the mother.
May also have a role in preventing cervical ripening during pregnancy.
Role of hCG
regulates glucose availability for the fetus, it is an insulin antagonist that increases maternal metabolism and use of fat as an energy substrate and reduces glucose uptake and use by maternal cells. As a result, more glucose is available for transport to the fetus. Thus, this acts as a growth-promoting hormone, promoting fetal growth by altering maternal metabolism.
hPL
production of hPL by the syncytiotrophoblast begins ___-____ days after conception (____-____ days after implantation)
12-18 (5-10)
hPL levels ____ during pregnancy and _____ near term
rise; peak
the most abundant placental secretory product
hPL
the main synthesis site of steroidogenesis (the production of estrogen and progesterone) in early pregnancy
corpus luteum
at 6-8 weeks gestation, the _________________ takes over steroidogenesis (the production of estrogen and progesterone) as the main site of synthesization
placental syncytiotrophoblast
acts to decrease myometrial activity/irritability
contrict myometrial vessels
decrease sensitivity of the maternal respiratory center to CO2
inhibit prolactin secretion
suppresses maternal immune reaction to fetal antigens
relaxes smooth muscle in GI & urinary systems
incrases basal body temp
increases Na+ and Cl- excretion
role of progesterone in pregnancy
serves as the substrate pool for fetal adrenal gland production of glucocorticoids and mineralocorticoids
progesterone
produces early in pregnancy by corpus luteum and later in pregnancy by the placenta
***is dependent on the fetus
estrogen
enhances myometrial activity
promotes myometrial vasodilation
increases sensitivity of the maternal respiratory center to carbon dioxide
softens fibers in the cervical collagen tissue
increases pituitary secretion of prolactin
increases serum binding proteins and fibrinogen
decreases plasma proteins
increases the sensitivity of the uterus to progesterone in late pregnancy.
estrogen
involves bidirectional movement of gases, nutrients, waste materials, drugs, and other substances across the placenta from maternal-to-fetal circulation or from fetal to maternal circulation
placental transport
simple (passive) diffusion, facilitated diffusion, active transport, pinocytosis, endocytosis, bulk flow, solvent drag, accidental capillary breaks, and independent movement
mechanisms of placental transfer
which placental transfer methods are mediated by protein and other transport substances
Facilitated diffusion and active transport
major mechanism of placental transfer
diffusion
movement of a substance from higher to lower concentration or electrochemical gradients
simple (passive) diffusion
substances that pass through placenta via _________
water, electrolytes, oxygen, carbon dioxide, urea, simple amines, creatinine, fatty acids, steroids, fat-soluble vitamins, narcotics, antibiotics, barbiturates, and anesthetics
substances that pass via simple diffusion
transport via protein transporters to move substances across the placental membrane. Movement is from higher to lower concentration or electrochemical gradients.
facilitated diffusion
glucose, oxygen, and waste products (lactate) are transported through placenta via:
facilitated diffusion
substances that cross placenta via ____________:
Amino acids, potassium, water-soluble vitamins, calcium, phosphate, iron, and iodine
active transport
invagination in the surface of a cell that forms intracellular membrane bound vesicles
endocytosis
occurs on the opposite side of the cell with fusion of the vesicle to the membrane and release of the vesicles’ contents.
exocytosis
•These mechanisms are necessary to transfer molecules too large for diffusion or for which no carrier transport exists
endocytosis and exocytosis
umbilical cord may be seen on U/S at ___ days and well-established by _____ weeks
42; 8-9
begin to develop soon after fertilization and continue to grow until about 28 weeks’ gestation
amnioin and chorion
the innermost amniotic epithelium is involved in amniotic fluid exchange and pH regulation
The outer membrane, contains blood vessels that atrophy as pregnancy advances, but no nerves
amnion and chorion function
a major site of prostaglandin (PG) synthesis and metabolism
fetal membranes
