L9 Physiology of the Uterus and Placenta Flashcards
Layers of the Uterus?
Endometrium: Stratum basalis, Stratum functionalis
Myometrium (3 layers of smooth muscle)
Inner longitudinal
Middle Circular layer
Outer Longitudinal
Perimetrium: outer serosa layer of the uterus,
equivalent to peritoneum
____________________Phase (D________):
- During menses, spiral arterioles in the stratum functional layer contract, resulting in ischemia, leading to degeneration of the ______________ layer.
- Arteries rupture, and rapid blood flow infiltrates and breaks down edematous tissue, eventually dislodging necrotic __________ layer, which is lost.
- The __________ layer is unaffected because it is supplied by straight arteries.
Menstrual Phase (D1-4)
- During menses, spiral arterioles in the stratum functional layer contract, resulting in ischemia, leading to degeneration of the functionalis layer.
- Arteries rupture, and rapid blood flow infiltrates and breaks down edematous tissue, eventually dislodging necrotic functional layer, which is lost.
- The basal layer is unaffected because it is supplied by straight arteries.
Proliferative Phase (D5-14)
Under the influence of FSH and LH, ovarian follicles begin to secrete increasing amounts of estrogen. This acts upon the stratum basalis and stimulates cell proliferation.
It also promotes the development of endometrial glands and the vascularization of the stromal layer. Over the course of the proliferative phase, the stratum functionalis layer is regenerated
_______________________ Phase (D_______):
Under the influence of FSH and LH, ovarian follicles begin to secrete increasing amounts of ___________. This acts upon the ______ and stimulates cell proliferation.
It also promotes the development of endometrial glands and the vascularization of the stromal layer. Over the course of the proliferative phase, the______________ layer is regenerated
Proliferative Phase (D5-14)
Under the influence of FSH and LH, ovarian follicles begin to secrete increasing amounts of estrogen. This acts upon the stratum basalis and stimulates cell proliferation.
It also promotes the development of endometrial glands and the vascularization of the stromal layer. Over the course of the proliferative phase, the stratum functionalis layer is regenerated
______________________ Phase (D__________)
- Highly vascularized endometrium is dependent on ________________ (from the Corpus Leuteum) for its viability, which in turn is dependent on pituitary LH for its viability
- The stroma becomes quite loose and edematous and the endometrium reaches its maximum thickness.
- High levels of progesterone and estrogen eventually inhibit ______________ production by negative feedback regulation and the CL begins to degenerate and die
- This leads to a drop in _________ production, signalling the demise of the endometrium (ie. menses)
Secretory Phase (D15-28)
- Highly vascularized endometrium is dependent on progesterone (from the Corpus Leuteum) for its viability, which in turn is dependent on pituitary LH for its viability
- The stroma becomes quite loose and edematous and the endometrium reaches its maximum thickness.
- High levels of progesterone and estrogen eventually inhibit pituitary LH production by negative feedback regulation and the CL begins to degenerate and die
- This leads to a drop in progesterone production, signalling the demise of the endometrium (ie. menses)
Spiral arteries supply the __________________
Spiral arteries supply the stratum functionalis.
They are specially adapted resistance vessels designed to prevent excessive haemorrhaging during menstruation and placentation.
Process of Pseudovasculogenesis?
During placentation cytotrophoblasts differentiate from an epithelial phenotype to an endothelial phenotype => transforms spiral artery resistance vessels to high capacitance vessels capable of providing placental perfusion adequate to sustain the fetus
Pathogenesis of PreEclampsia?
Cytotrophoblasts fail to adopt an invasive endothelial phenotype. Instead, invasion of the spiral arteries is shallow and they remain small caliber, resistance vessels. This may result in placental ischemia.
HELLP is the medical term for one of the most serious complications of pre-eclampsia, in which there is a combined liver and blood clotting disorder.
What is the Decidual Reaction?
Maternal defence against Pseudovasculogenesis
If Implantation occurs, stromal cells proliferate and enlarge forming a dense cell matrix that is designed to limit the invasion of trophoblast cells of the early embryo
Harder for trophoblast to penetrate this layer to reach the maternal blood supply (Spiral arteries)
Role of IGFBP-12 at the Fetomaternal Interface?
Stromal cells of endometrium make IGF Binding protein 1 trophoblasts created PAP to counter the mother’s IGFBP
Endocrine Cells of Placenta?
Syncytiotrophoblasts/Cytotrophoblasts: transient endocrine structure located in placenta that secrete a vast array of polypeptide and steroid hormones
Significance of Chorionic Gonadotrophin?
- Glycoprotein hormone with structural homology to LH, FSH and TSH
- Made in syncytiotrophoblasts
- Detectable in maternal circulation 7-10 days after implantation
- Functionally analogous to LH (‘luteotropic’): acts on corpus lutetium and ovary to upregulate progesterone (ESSENTIAL to maintain pregnancy_)
______________________ may be measured as a marker of fetal viability since normal fetal adrenal, liver, and/or placental function are required
Maternal E3 levels may be measured as a marker of fetal viability since normal fetal adrenal, liver and/or placental function are require
Placental progesterone production depends on supply of _________________________ from _____________________
Placental progesterone production depends on supply of cholesterol from maternal circulation.
Placental estrogen production depends on a supply of ________________________from ________________________
Placental estrogen production depends on supply of DHEA (Adrenal Androgen) from fetal adrenal gland.
