Human A&PBIO 304 · American River College ← Week 08 pre-work

BIO 304 · Week 08 · Interactive Workbook

Pregnancy A&P (Basics)

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Part 1 of 4 · Recall

Fill in the blanks

Type the term that completes each statement, using the word bank. Pull it from memory first.

Word bank

Glucose toleranceProstaglandinsRelaxinMaternal blood lakesGFRMorulaTidal volumeImplantationProlactinEstrogenThird trimester (28-40 wks)Cortical reactionStage 3 (shortest)SiteHR

  1. usually ampulla of fallopian tube
  2. fast block to polyspermy after first sperm enters
  3. 16-cell solid ball; ~day 3
  4. ~day 7; trophoblast invades endometrium
  5. around chorionic villi; no direct mixing of blood
  6. maternal effects, uterine growth, breast development
  7. softens cervix; relaxes pelvic ligaments
  8. rapid growth; mother's adaptations maximal
  9. up 10-20 bpm
  10. up; minute ventilation up ~50%
  11. up ~50%
  12. increased insulin resistance (hPL); gestational diabetes risk
  13. delivery of placenta; usually within 30 min
  14. soften cervix; stimulate contractions
  15. milk production after delivery (estrogen/progesterone fall is the trigger)

Define it: high-yield vocabulary

Write a clear definition in your own words for each term.

  1. Fertilization
  2. Zygote
  3. Blastocyst
  4. Implantation
  5. Placenta
  6. hCG
  7. Progesterone (in pregnancy)
  8. Umbilical cord
  9. Trimester
  10. Stages of labor
  11. Oxytocin
  12. Colostrum

Part 2 of 4 · Anatomy lab

Draw and label

Box A. Fertilization to implantation

Directions

  1. Draw a horizontal arrow with five labeled stages, left to right.
  2. Stage 1: Fertilization. A sperm meets the egg in the upper fallopian tube. Draw both with the sperm head entering the egg cytoplasm. Result: zygote (2n).
  3. Stage 2: Cleavage. Repeated cell divisions, no growth. Show a 2-cell, then 4-cell, then 8-cell embryo.
  4. Stage 3: Morula. A solid ball of about 16 cells.
  5. Stage 4: Blastocyst. A hollow ball with an inner cell mass (becomes embryo) and outer trophoblast (becomes placenta). Show a fluid-filled cavity inside.
  6. Stage 5: Implantation. The blastocyst burrows into the endometrium of the uterus around Day 6 to 7 after fertilization. The trophoblast cells invade and begin forming the placenta.
  7. Label every stage.
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Box B. Mature placenta

Directions

  1. Draw a cross-section of a mature placenta and the surrounding uterine wall.
  2. Show maternal blood spaces (lacunae) in the placenta filled with maternal blood. Show the maternal arteries (spiral arteries) supplying these lacunae.
  3. Show fetal villi projecting into the maternal blood spaces. The villi contain fetal capillaries.
  4. Critical: maternal and fetal blood DO NOT MIX. They are separated by the placental barrier (trophoblast layer plus fetal capillary endothelium). Gases, nutrients, antibodies, drugs, and wastes diffuse across.
  5. Show the umbilical cord leaving the placenta, containing two umbilical arteries (carrying deoxygenated blood FROM fetus TO placenta) and one umbilical vein (carrying oxygenated blood FROM placenta TO fetus). Label.
  6. Note: this is the only place in the body where arteries carry deoxygenated blood and a vein carries oxygenated blood.
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Structures to label

Label each on your drawing.

  1. Zygote
  2. Cleavage
  3. Morula
  4. Blastocyst
  5. Inner cell mass
  6. Trophoblast
  7. Implantation
  8. Endometrium
  9. Placenta
  10. Maternal blood (lacuna)
  11. Spiral artery
  12. Fetal villus
  13. Fetal capillary
  14. Placental barrier
  15. Umbilical cord
  16. Umbilical artery (2)
  17. Umbilical vein (1)
  18. hCG
  19. Estrogen (placental)
  20. Progesterone (placental)

Part 3 of 4 · Physiology lab

Reason it through

A. Hormonal changes through pregnancy

1. hCG (human chorionic gonadotropin): peaks at about 8 to 10 weeks, then declines. Source? Function?
2. Progesterone: rises throughout pregnancy. Source shifts from corpus luteum to placenta around week 10. Function?
3. Estrogen: rises steadily throughout pregnancy, made by the placenta. Function in the third trimester?
4. Relaxin: produced by ovary and placenta; rises late in pregnancy. Function at parturition?
5. Oxytocin: surges at parturition. Source? Mechanism (positive feedback during labor)?
6. Prolactin: rises through pregnancy and after delivery. Function?

B. Synthesis

1. Home pregnancy tests detect hCG in the urine. Explain why hCG is a reliable early marker, why it peaks at 8 to 10 weeks, and why levels in ectopic pregnancy or miscarriage are often lower than expected for gestational age.
2. Gestational diabetes develops in some women because placental hormones (especially human placental lactogen) increase insulin resistance. Predict the maternal blood glucose pattern, the consequences for the fetus (macrosomia), and why blood sugar typically normalizes after delivery.
3. Parturition (labor) involves a positive feedback loop with oxytocin. Identify the stimulus, the receptor, the response, and the amplifying step. Why is positive feedback (rather than negative feedback) the right architecture for this physiological event?

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