Physiology of Pregnancy, Parturition and Lactation Flashcards
The female reproductive tract is an important regulator of sperm transport. The main player is estrogen which does who two things to help the sperm each it’s target
- Estrogen causes the cervix to produce a watery mucus
2. estrogen causes contraction of the myometirum to help propel sperm upward toward the oviduct
what three barriers must the sperm breach in order to get to the egg?
- cumulus
- zona pellucida
- plasma membrane of the egg (aka oolemma)
which ZP glycoprotein must the sperm interact with to begin fertilization?
ZP3
What is the acrosmal reaction?
Increase in Ca inside the sperm cell triggers fusion of the outer acrosomal membrane with the sperm cells plasma membrane and results in the exocytosis of most of the acrosomal contents
what is the corticol reaction?
Initiated by increase in Ca inside the oocyte .
-massive exocytsosis of corticol granules seen shortly after sperm - oocyte fusion. the release of these granules release enzymes that act on glycoproteins in the zona pellucida and cause them to harden
what process is considered the end of fertilization and the beginning of embryonic devlelopment?
The mingling of chromosome (syngamy)
around what day does fertilization typically occur?
Day 15 or 16 of menstrual cycle
by day 3, how many cleavage has occurred and what is it called?
3 cleavage and is called a 16 cell morula
by what day does implantation usuaully occur?
by day 6 or 7 following ovulation
Trophectoderm becomes the _ and the inner cell mass becomes _.
Trophectoderm forms the placenta and XE tissues
ICM = embryo
At the time of implantation, the trophoblast differentiates into 2 cell types:
- cytotrophoblasts (inner cell layer)
2. Syncytiotrophoblasts (outer layer of multinuclear and multicellular ells; w/o cellular boundaries)
what secretes hCG?
trophoblasts cells of the blastocyst
which cells are adhesive (has adherins and integrins that bind to uteirne surface epithelial), invasive and has endocrine functions such that it releases hcG at the onset of implantation, and make progesterone.
syncytiotrophoblasts
what plays the major role int he dissolution of the zona pellucida?
lytic factors in the endometrial cavity. Such factors include plasmin which appears in the plasminogen form int he uterine cavity, and the blastocyst contains factors that can activate it
what are three stages of implantation/
apposition
adhesion
invasion
what is apposition?
- earliest contact between the blastocyst wall, trophoectoderm, and endometrial epithelium
- usually occurs where there is a mslal crypt in the endometrium
- Apposition starts at the place on the blastocyst where there has been enough lysis and that portion meets with the decidua
what endometrial surface epithelial cells is involved in apposition?
MUC1
In the adhesion stage of implantation, trohoblast attaches to the uterine epithelium through microvilli found on _
the trophoblast
during which stage of implantation, does the trophoblastic cells rapidly proliderate and differentiate into the inner cytotrophoblast and the outer syncytiotrophoblast
invasion
In the decidualization process, the stromal cells derived from the fibroblast-like cells within the endometrium require _ to maintain their progesterone receptors.
progesterone
in the development of the placenta, the invading syncytiotrophoblast breaks through into the endometrail _ first and then into the _
veins first and then arteries.
proliferation of which (cytotophoblast or syntiotrophoblast) creates small mounds that forms the primary chorionic vili?
cytotrophoblast
how is the secondary chorionic villi formed?
mesenchymal cells from the XE mesoderm invade the primary chorionic villi
when does secondary chorionic villi become tertiary?
when the mesenchymal cells form fetal blood vessels de novo
the mature placenta is composed of three majjor structure:
- chorionic villi
- intervillous space
- decidual basalis
what represents the functional unit of the placenta and is responsible for greatly increasing the surface area for maternal-fetal exchange?
Chorionic villi
what factors regulate maternal blood flow in the intervillous space?
- maternal arterial blood pressure,
- intra-uterine pressure
- pattern of uterine contraction
Do umbilical arteries carry oxygenated or deoxygenated blood?
deoxygenated blood, unlike systemic arteries after birth.
what imporant functions do amniotic fluid have?
- serves as a mechanical buffer protecting the fetus from external physical insults
- fetus excretes waste products through it
describe the gas composition of maternal blood coming into the intervillous space.
It’s similar to that of system arterial blood: P02 = 100 mHg; PCO2 = 40 mm Hg; pH = 7.4
What causes the drop in Po2 of the blood int he intervillous space?
The diffusion of O2 from the maternal blood into the chorionic villi of the fetus
Despite the relatively low Po2 of the maternal blood int he intervillous space, the fetus does not suffer fromlack of O2, why?
Fetal Hb has a much higher affinity for O2 than does maternal Hb, the fetal Hb can extract O2 from the maternal Hb
Does the following move across the placenta:
- waste prodcuts urea and creatinine
- Lipid-soluble steroid hormones
- glucose
- Amino acids
- Vitamins and minerals
- LDL, transferrin, hormones, ab
- passive movement
- simple diffusion; shuttle among the mother, the placenta and the fetus
- facilitated diffusion
- secondary active transport
- active transport
- receptor-mediated endocytosis
what is the first hormone produced by the syntiotrophoblast?
hCG
In pregnancy test, which subunit of hCG does antibodies bind to?
b-hcg
to what receptors do hCG bind to?
LH receptors
what is the 1/2 life of hcg?
up to 30 hrs
What is the primary action of hCG?
stimulate LH receptor on corpus luteum