Updated: 7/7/2018

Placental Components

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https://upload.medbullets.com/topic/103007/images/placental-components.jpg
https://upload.medbullets.com/topic/103007/images/nutrition_exchanges.jpg
 
Overview
  • Placenta
    • a barrier that prevents blood exchange between mother and fetus but allows exchange of oxygen, carbon dioxide, and nutrients
    • composed of two components
      • fetal
      • maternal
Fetal component
  • Tertiary chorionic villi
    • villi that grow from the chorion to increase the surface area for exchange
    • villi that have grown in size, branched, and vascularized
    • inner layer derived from cytotrophoblast
    • outer layer derived from syncytiotrophoblast
      • secretes hCG to maintain the production of progresterone from the corpus luteum during the 1st trimester
      • hCG is a heterodimer that has the same alpha subunit as FSH, LH, and TSH, but beta subunit is what differentiates the hormones 
Maternal component
  • Decidua basalis
    • derived from the endometrium of the uterus
    • shed from mother after birth
    • mother's blood fills the lacunae and gas and nutrient exchange occurs across the fetal portion of the placenta
Placental complications
  • Normal 
    • attaches in superior posterior part of uterus 
  • Placenta previa
    • attaches in inferior part of uterus covering internal os, leading to bleeding as uterus dilates during pregnancy
  • Placenta
    • accreta
      • attaches deep in uterus and invades into myometrium but not entirely
    • increta
      • invades entire thickness of myometrium
    • percreta
      • penetrates entire thickness of myometrium and into serosa of uterus leading to possible attachment to bladder or rectum
  • Placenta abruptio
    • prematurely detaches from uterus, associated with maternal hypertension
  • Preeclampsia
    • sudden development of the following after week 20 of gestation
      • maternal hypertension greater than 160/110 mm Hg
      • proteinuria
      • can progress to eclampsia (above conditions plus seizures)
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Questions (2)
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(M1.EB.14.13) Hormone balance is essential for maintaining a normal pregnancy. Early on, elevated progesterone levels are needed to maintain pregnancy and progesterone is produced in excess by the corpus luteum. In the normal menstrual cycle the corpus luteum involutes, but this process is impeded during pregnancy because of the presence of which hormone? Tested Concept

QID: 105183
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Cortisol

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(0/26)

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Human chorionic gonadotropin

81%

(21/26)

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Estrogen

4%

(1/26)

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Progesterone

15%

(4/26)

5

Inhibin A

0%

(0/26)

M 1 E

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