Anatomical Changes in Pregnancy Flashcards
What are the three layers of the uterus?
- Endometrium 2. Myometrium 3. Perimetrium
What is the functional layer of the uterus that adapts for implantation called?
Endometrium
What role does the myometrium play during labor?
Generates contractile forces used for expulsion
What happens to the dominant follicle during the ovarian cycle?
It produces estrogen while growing to thicken urterine lining then it ovulates giving rise to the corpus luteum
What is the corpus luteum and what does it produce?
It is the structure formed after ovulation that produces progesterone
What occurs to the corpus luteum if pregnancy does not happen?
It dies, leading to decreased progesterone and the onset of menstruation
What is decidualisation?
The conversion of endometrium to a tissue type that supports implantation
What happens to the endometrium during pregnancy?
It thickens, glands elongate to produce uterine milk, and spiral arteries develop
What do spiral arteries provide during pregnancy?
Blood to the placenta when it implants
What is the maternal surface of the placenta called?
Decidua
What is the function of the myometrium’s interlacing fibers during labor?
They constrict vessels to prevent hemorrhage
What tissues compose the cervix and what do they allow for?
Collagen, elastic tissue, smooth muscle, and ground substance which allow extensive changes in shape when needed whilst maintaining competence and compliance
What is the definition of compliance in the context of the cervix?
The ability to deform when stress is applied
What does competence refer to in cervical structure?
The capacity to support structural load
What are the stages of cervical remodelling?
Softening, ripening, dilation, and repair
What occurs to cervical structure during the softening stage of cervical remodelling?
Gradual loss of compliance while maintaining competence
What happens during the ripening stage of the cervix?
Loss of compliance and competence, allowing the baby to push down the birth canal
What are the two main muscles in the pelvic diaphragm?
Levator Ani and Coccygeus
What changes occur in the pelvis to facilitate birth?
Pubic symphysis softens and SI joint ligaments relax
What cardiovascular change occurs during pregnancy?
Increased blood volume, mostly located in the placenta
How is the placenta connected to the maternal uterus?
Via spiral arteries and maternal veins
What are the two cell lineages of the placenta?
Cytotrophoblast and Syncytiotrophoblast
What is the role of interstitial extravillous trophoblasts (iCTBs)?
To invade the decidua and interact with maternal cells for immune acceptance
What do endovascular extravillous trophoblasts (eCTBs) modify?
Maternal spiral arteries to regulate blood flow to the placenta
What is a significant risk associated with impaired spiral artery remodelling?
Maternal and fetal death, related to conditions like preeclampsia
What type of placenta is in humans and what is it’s main characteristic?
Haemochorial placenta characterized by blood washing over villi
What cells form an embryo?
Trophoblasts and inner cell mass
Define lacuna
Lacuna are pockets of blood formed by the growth of spiral arteries
What are chorionic villi?
Finger-like projections of developing placenta made of CTBs, STBs, and mesoderm (from baby) which project into lacunae
Differentiate between villous TBs and extravillous TBs
villous TBs include CTBs and STBs and combine to create villi and layer seperating mother and baby’s blood
extravillous TBs are specialised CTB daughter cells and can be interstitial EVTBs or endovascular EVTBs
describe the role of iEVTBs and eEVTBs
iEVTBs: invade decidua and interact with maternal cells to regulate immune acceptance of fetus
eEVTBs: modify maternal spiral arteries to modify blood flow to placenta
