Questions and Answers
At what point does maternal Immunoglobulin G (IgG) begin to be transported from mother to fetus?
What developmental structure gives rise to the primitive umbilical cord?
What causes the physiological umbilical hernia during fetal development?
What structure occupies the space between the amnion and the chorionic plate?
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What characteristic feature of umbilical arteries aids in their rapid constriction after the cord is tied off?
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What is a common change in the villi at the end of pregnancy?
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What characteristic of the fetus is observed at the beginning of the sixth month?
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Which change can lead to the appearance of a whitish cotyledon?
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At 37 weeks, how much amniotic fluid is typically present?
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At what length is the CRL approximately at 6 to 7 months of pregnancy?
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What is the primary reason a fetus born early in the sixth month struggles to survive?
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What primarily contributes to the production of amniotic fluid?
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What structural change occurs in the basement membranes of fetal capillaries towards the end of pregnancy?
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What significant change occurs in the last two months of pregnancy regarding the fetus's appearance?
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How long is the length of pregnancy calculated from the last normal menstrual period (LNMP)?
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What is Vernix caseosa and when does it appear on the fetus?
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What is the approximate weight of the fetus at 6 to 7 months of pregnancy?
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What structural change occurs in the trophoblast during the sixth month?
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What is the primary method by which the fetus exchanges gases with the maternal circulation?
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How much oxygen does the fetus typically extract from the maternal circulation per minute at term?
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Which structure is NOT mentioned as passing through the primitive umbilical ring at the 5th week of development?
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What is critical to ensuring an adequate oxygen supply to the fetus?
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Which category of substances is NOT listed as rapidly exchanged between the mother and fetus?
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What is the first stage of labor?
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What does Small for Gestational Age (SGA) indicate?
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Which of the following is a risk associated with SGA infants?
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What physiological change occurs in the myometrium during the last weeks of gestation?
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Which factor is considered a major growth promoter during development?
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Which complication is not directly related to SGA infants?
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What is the typical interval for the onset of contractions during labor?
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What distinguishes symmetric growth restriction from asymmetric growth restriction in SGA infants?
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Study Notes
Fetal Development Stages
- Maturation of tissues and organs occurs, with rapid body growth by the sixth month.
- Fetal skin appears reddish and wrinkled due to insufficient underlying connective tissue.
- Fetuses born at the early sixth month face significant survival challenges.
- Crown-rump length (CRL) and crown-heel length (CHL) are crucial measurements of fetal size.
Pregnancy Timeline
- Pregnancy lasts approximately 280 days (40 weeks) from the last normal menstrual period (LNMP).
- More accurately, it is about 266 days (38 weeks) after fertilization.
Fetal and Maternal Interactions
- By six to seven months, CRL reaches around 25 cm, and weight is approximately 1,100g, with a 90% survival chance for infants born at this stage.
- Trophoblast development includes numerous secondary and tertiary villi, giving a radial appearance.
- Blood flow through the placenta is critical for oxygen uptake; the fetus extracts 20 to 30 ml of oxygen per minute.
Exchange Mechanisms
- Gases, nutrients, and electrolytes are exchanged rapidly, increasing as pregnancy progresses.
- Key nutrients include amino acids, free fatty acids, carbohydrates, and vitamins.
- Maternal antibodies, particularly IgG, begin transferring to the fetus around 14 weeks.
Umbilical Structures
- The primitive umbilical ring is formed at about five weeks, containing the connecting stalk and yolk stalk.
- The connecting stalk houses the allantois and umbilical vessels (two arteries and one vein).
Amniotic Fluid Dynamics
- Amniotic fluid volume increases significantly throughout pregnancy, from approximately 30 mL at 10 weeks to between 800 – 1,000 mL by 37 weeks.
Changes in Pregnancy
- Structural changes occur in the placenta toward the end of pregnancy, including increased fibrous tissue and thickening of membranes.
- Excessive fibrinoid formation can lead to placental infarction, impacting fetal health.
Parturition Process
- Parturition, or childbirth, involves tissue changes during the final weeks of gestation, including myometrial thickening and cervical softening.
- The process of labor includes three stages: effacement and dilation, delivery of the fetus, and delivery of the placenta.
Small for Gestational Age (SGA)
- SGA is defined as being below the 10th percentile for gestational age; may be pathologically small or constitutionally small.
- SGA infants face risks such as perinatal asphyxia and hypoglycemia.
Insulin-like Growth Factor-1 (IGF-1)
- IGF-1 is essential for growth during fetal development due to its mitogenic and anabolic effects.
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Description
Explore the physical changes and growth that occur during the sixth month of fetal development. Delve into the appearance of the fetus, including skin characteristics and the challenges faced by early births. This quiz enhances your understanding of human maturation processes.
