Pregnancy 2 Flashcards
(17 cards)
What happens during the conception stage, and where does fertilization occur?
During conception, the sperm and ovum combine to form a fertilized zygote. Fertilization occurs in the uterine tubes (oviduct), typically around day 14 of the menstrual cycle.
What 3 key processes occur during the germinal stage of development?
The zygote divides and becomes a blastocyte (hollow ball of cells).
The blastocyte implants in the uterus.
The placenta begins to form from the trophoblast (outer layer of the blastocyte).
This stage lasts from conception to ~2 weeks.
During the embryonic stage, what are the three germ layers, and what do they develop into?
Ectoderm: Skin, hair, nails, and nervous system.
Mesoderm: Bones, muscles, heart, kidneys, and gonads.
Endoderm: Digestive and respiratory systems.
This stage occurs from day 15 to the end of the 8th week.
What major developments occur during the fetal stage?
Continued growth and organ system development.
The fetus digests amniotic fluid, urinates, and circulates blood through the heart.
This stage begins at week 9 and continues until birth.
What is the role of the foramen ovale in fetal circulation?
The foramen ovale shunts blood from the right atrium to the left atrium, bypassing the underdeveloped lungs.
What is the role of the ductus arteriosus in fetal circulation?
The ductus arteriosus shunts blood from the pulmonary artery to the aorta, bypassing the lungs. It closes after birth when the baby takes its first breath.
Why does fetal hemoglobin have a higher affinity for oxygen, and how does this benefit the fetus?
Fetal hemoglobin binds oxygen more effectively, facilitating oxygen transfer from the placenta. After birth, the breakdown of fetal hemoglobin provides the infant with iron stores for up to 6 months.
What is a critical period, and why is it important?
A critical period is a specific time when tissue or organ cells are genetically programmed to multiply. Developmental disruptions during this time cannot be corrected later, making it crucial for proper growth (e.g., neural tube formation at weeks 3-4).
When does the placenta become fully functional, and what are its 3 key roles?
The placenta becomes fully functional by the second trimester (~12 weeks). Its roles include:
Nutrient and gas exchange.
Waste removal.
Hormone production (e.g., hCG, estrogen, progesterone).
What 4 modes of transport ensures nutrient transport from the plaenta to the fetus?
Nutrients cross the placenta through:
Passive diffusion: High to low concentration.
Facilitated diffusion: Uses carriers to speed up transfer.
Active transport: Requires ATP and cell receptors.
Endocytosis: Engulfs nutrients via placental membrane.
How does placental dysfunction affect pregnancy?
Placental dysfunction, such as inadequate spiral artery remodeling, can restrict blood flow and lead to complications like high blood pressure or preeclampsia.
What are 6 key physiological changes that occur during pregnancy?
Increased blood volume and cardiac output.
Higher respiration rate and glucose production.
Reduced gut motility leading to constipation.
Expansion of adipose stores, uterus, and maternal organs.
Increased urination due to higher GFR.
Slight suppression of the immune system in the thymus.
How does hormonal regulation change during pregnancy?
Early pregnancy sees increased hCG from the trophoblast.
Progesterone, estradiol, and hPL rise steadily as the placenta takes over hormone production after the corpus luteum phase.
What major events occur during the 1st trimester (Weeks 0-13)?
Fertilization, germinal stage, implantation, and placentation.
Critical periods for tissue differentiation (e.g., neural tube formation).
Development of the placenta.
The pregnancy is most vulnerable to toxins and nutrient deficiencies.
What is the difference between the maternal anabolic and catabolic phases of pregnancy?
Anabolic phase (1st & 2nd trimesters): Building maternal nutrient stores, fat, and blood volume.
Catabolic phase (3rd trimester): Mobilizing nutrient stores and increasing levels of glucose and fatty acids in maternal blood for fetal use.
Why is adequate folate intake crucial during the periconception period?
Folate supports neural tube formation, which occurs during weeks 3-4. Deficiency can lead to neural tube defects like spina bifida.
What are the risks of iron deficiency before pregnancy?
Increased risk of maternal and infant iron deficiency.
Greater likelihood of preterm delivery.
Low iron stores in the infant.
