placental memberane
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Questions and Answers

What is the function of the placenta?

  • To facilitate exchange of oxygen and nutrients between maternal and fetal blood (correct)
  • To form the decidua basalis
  • To obliterating the uterine cavity
  • To connect the umbilical cord to the fetus

    • What is the outermost fetal membrane?

  • Umbilical vesicle
  • Allantois
  • Amnion
  • Chorion (correct)

    • What develops from the chorionic sac?

  • Fetal part of the placenta (correct)
  • Decidua basalis
  • Amnion
  • Umbilical cord

    • What is the functional layer of endometrium that separates from the remainder of the uterus after childbirth?

    <p>Decidua</p> Signup and view all the answers

    What is the remaining part of the decidua?

    <p>Decidua parietalis</p> Signup and view all the answers

    What is the effect of increasing progesterone levels on decidua cells?

    <p>They enlarge to form decidual cells</p> Signup and view all the answers

    What is the placenta composed of?

    <p>A maternal and a fetal part</p> Signup and view all the answers

    What connects the placental circulation with the fetal circulation?

    <p>The umbilical cord</p> Signup and view all the answers

    What is the maternal part of the placenta derived from?

    <p>Endometrium</p> Signup and view all the answers

    What is the superficial part of the decidua?

    <p>Decidua capsularis</p> Signup and view all the answers

    What is the function of the umbilical vesicle during the second and third weeks of pregnancy?

    <p>Transfer of nutrients to the embryo</p> Signup and view all the answers

    What is the Allantois associated with in the early embryo?

    <p>Early blood formation and development of the urinary bladder</p> Signup and view all the answers

    What is the result of the separation of the blastomeres in MZ twins?

    <p>Two embryos, each in its own amniotic sac, within the same chorionic sac and sharing one placenta</p> Signup and view all the answers

    What is the frequency of Monozygotic twinning in different populations?

    <p>It is approximately the same in all populations</p> Signup and view all the answers

    What is the risk of chromosomal anomalies and fetal morbidity in multiple gestations compared to single pregnancies?

    <p>Higher in multiple gestations</p> Signup and view all the answers

    What is the purpose of the amniotic fluid in fetal development?

    <p>It enables the fetus to move freely, aiding muscular development</p> Signup and view all the answers

    What is the result of the incorporation of the endoderm of the umbilical vesicle into the embryo?

    <p>Formation of the lungs and alimentary canal</p> Signup and view all the answers

    What is the role of the primordial germ cells in the umbilical vesicle?

    <p>They migrate to the developing gonads and differentiate into spermatogonia or oogonia</p> Signup and view all the answers

    What is the difference between Dizygotic and Monozygotic twins?

    <p>DZ twins develop from two zygotes, while MZ twins develop from one zygote</p> Signup and view all the answers

    Why does the frequency of Dizygotic twinning increase with maternal age?

    <p>Because of an increase in the release of hormones</p> Signup and view all the answers

    By what week does the uterus and fetus reach the level of the umbilicus?

    <p>20 weeks</p> Signup and view all the answers

    What stimulates the production of oxytocin and prostaglandin?

    <p>Estrogen</p> Signup and view all the answers

    What is the first stage of labor?

    <p>Dilation</p> Signup and view all the answers

    What is the average duration of the first stage of labor?

    <p>12 hrs</p> Signup and view all the answers

    What is the shape of the placenta after birth?

    <p>Discoid</p> Signup and view all the answers

    What is the connection between the placenta and the fetus?

    <p>Umbilical cord</p> Signup and view all the answers

    What is the main function of the amniotic fluid?

    <p>To provide a protective environment</p> Signup and view all the answers

    What is the source of most of the amniotic fluid?

    <p>Maternal tissue</p> Signup and view all the answers

    How much amniotic fluid is swallowed by the fetus daily?

    <p>400ml/day</p> Signup and view all the answers

    What is the term for the attachment of the umbilical cord to the fetal membranes?

    <p>Velamentous insertion</p> Signup and view all the answers

    What is the placental membrane composed of until the 20th week?

    <p>Four layers: syncytiotrophoblast, cytotrophoblast, connective tissue of the villi, and endothelium of fetal capillaries</p> Signup and view all the answers

    What is the main function of the placenta in terms of metabolism?

    <p>Synthesis of glycogen, cholesterol, and fatty acids</p> Signup and view all the answers

    What is the term for the external layer of trophoblastic cells on the maternal surface of the placenta?

    <p>Cytotrophoblastic shell</p> Signup and view all the answers

    What is the purpose of the intervillous space in the placenta?

    <p>To contain maternal blood for the exchange of gases and nutrients</p> Signup and view all the answers

    What is the term for the process by which substances are transported in both directions between the fetal and maternal blood?

    <p>Placental transport</p> Signup and view all the answers

    What is the name of the hormone produced by the placenta that maintains the corpus luteum?

    <p>Human chorionic gonadotropin (hCG)</p> Signup and view all the answers

    What is the term for the waste products produced by the fetus that are excreted through the placenta?

    <p>Urea, uric acid, conjugated bilirubin, and other waste products</p> Signup and view all the answers

    How does the placenta establish an adequate exchange of key molecules between the mother and embryo/fetus?

    <p>By invading the uterus to tap into its blood supply</p> Signup and view all the answers

    What is the term for the developing pregnancy from the time of fertilization until the end of the 8th week of gestation?

    <p>Embryo</p> Signup and view all the answers

    What is the term for the fusion of the amnion and smooth chorion to form a membrane?

    <p>Amniochorionic membrane</p> Signup and view all the answers

    Study Notes

    Placental Development and Circulation

    • The placenta is a feto-maternal organ with two components: a fetal part derived from the chorionic sac and a maternal part derived from the endometrium.
    • The placenta develops from the chorionic sac, which forms the villous chorion, and the decidua basalis, which forms the maternal part.
    • The decidua is the endometrium of the uterus during pregnancy, consisting of three regions: decidua basalis, decidua capsularis, and decidua parietalis.
    • The decidua separates from the remainder of the uterus after childbirth.

    Fetal and Maternal Circulation

    • Fetal circulation: poorly oxygenated blood passes through the umbilical arteries, placenta, and chorionic arteries, and then returns to the fetus through the umbilical vein.
    • Maternal circulation: maternal blood enters the intervillous space through spiral endometrial arteries, and returns to the maternal circulation through endometrial veins.
    • Reductions in uteroplacental circulation can result in fetal hypoxia and intrauterine growth restriction.

    Placental Membrane and Functions

    • The placental membrane separates fetal and maternal circulations, consisting of four layers: syncytiotrophoblast, cytotrophoblast, connective tissue, and endothelium of fetal capillaries.
    • The placenta has several functions:
      • Metabolism (synthesizing glycogen, cholesterol, and fatty acids)
      • Transport of gases and nutrients
      • Endocrine secretion (hCG, human chorionic somatomammotropin, etc.)
      • Protection
      • Excretion (fetal waste products)
    • The placenta allows for the transfer of substances between fetal and maternal blood through simple diffusion, facilitated diffusion, active transport, and pinocytosis.

    Hormones and Tumorigenic Properties

    • The placenta synthesizes protein hormones, including hCG, human chorionic somatomammotropin, and human chorionic thyrotropin.
    • The placenta has tumorigenic properties, invading the uterus to establish a blood supply and facilitate exchange of molecules between the mother and embryo/fetus.

    Umbilical Cord and Amniotic Fluid

    • The umbilical cord is a tube-like structure connecting the placenta to the fetus, carrying fetal blood to the placenta and maternal blood to the fetus.
    • The amniotic fluid is derived from maternal tissue and the fetus, serving as a protective environment for the developing embryo/fetus.
    • The amniotic fluid allows for symmetric external growth, acts as a barrier to infection, and permits normal fetal lung development.

    Fetal Development and Multiple Pregnancies

    • The embryo is defined as the developing pregnancy from fertilization to the end of the 8th week, after which it is called a fetus.
    • Multiple pregnancies increase the risks of chromosomal anomalies and fetal morbidity, with the frequency of dizygotic twinning showing racial differences.
    • Dizygotic twins develop from two zygotes and may be of the same sex or different sexes, while monzygotic twins are genetically identical and develop from one zygote.

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