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Pregnancy/Childbirth
Lecture Unit 3
Question | Answer |
---|---|
Capacitation | Period of sperm conditioning in female reproductive tract. Prepares acrosome for fertilization. Bumped against cilia. |
Fertilization | Combines the genetic material from the sperm and oocyte. Occurs in the uterine tube. Most commonly the ampula. |
Three phases of fertilization | 1. Corona Radiata Penetration. 2. Zona Pellucida Penetration. 3. Fusion of Sperm and Oocyte Plasma Membranes. |
1. Corona Radiata Penetration | Acrosome Reaction: acrosome releases enzymes to enable sperm to penetrate teh corona radiata. |
2. Zona pellucida Penetration | Acrosome continues to release enzymes to penetrate the zona pellucida. Zona pellucida hardens after 1 sperm penetrates, preventing polyspermy. |
3. Fusion of Sperm and Oocyte Plasma Membranes | Once the nucleus of sperm enters teh secondary oocyte, the oocyte completes second meiotic division. Sperm and ovum fuse, forming a single nucleus. |
Blastocyst | Trophoblast and Inner Cell Mass (Embryoblast). Implants into the stratum functionalis on day 7. |
Implantation | 7 days after fertilization. Zona pellucida begins to break down. Trophoblast subdivides: Cytotrophoblast-inner layer, Syncitiotrophoblast-outer layer. Burrows into the stratum functionalis of the endometrium. |
Human Chorionic Gonadotropin | Syncytiotrophoblast produces hCG. Signals the woman's body to continue uterine growth instead of menstruation. hCG levels are high enough in blood to be detected in urine after 2 weeks of pregnancy. Detected in pregnancy tests. |
Development of the Placenta | Maternal portion from stratum functionalis. Fetal portion from chorion. Mother & baby's blood never mix. Transfer: nutrients, gases, bacteria, viruses, alcohol, drugs, antibodies. Umbilical cord connects fetus to placenta. |
Chorionic villia | Branches of fetal blood vessels |
Sexual Differentiation of the Embryo | No difference before week 5. Genital (Gonadal) ridges become gonads in week 5. |
Presence of Testis Determining Factor (TDF) gene causes | genital ridges to become testes. Males have a TDF gene on the Y chromosome. |
Absence of TDF gene causes | genital ridges to develop into ovaries. Females have no Y chromosome or TDF gene. |
Development of Internal Organs | Embryos initially contain both male & female duct systems: paramesonephric & mesonephric ducts. Presence or absence of certain genes & hormones determines which duct system will degenerate. |
Internal Male Development | Paramesonephric duct degenerates. mesonephric duct remains: becomes epididymis & vas deferens in male embryos. |
Internal Female Development | Mesonephric duct degenerates. Paramesonephric duct remains: Becomes oviducts and uterus in female embryos. |
External Development | Genital tubercle becomes clitoris in females & glans penis in males. Labioscrotal swelling becomes labia majora in females & scrotum in males. |
True Hermaphrodite | Have both ovarian & testicular structures & ambiguous (or female) external genitalia. Very rare. Typically the ovarian & testicular structures are not functional. |
Psudohermaphrodite | Genetic sex and phenotypic sex don't match. Too much or too little testosterone during development. Congenital adrenal hyperplasia-1 in 10,000-18,000. Fetal adrenal glands produce excessive androgen. Female fetus appears more male. Much more common. |
Stages of labor | 1. dilation 2. expulsion 3. placental |
Dilation | Begins with first regular contractions & ends when cervix is fully dilated by baby's head. Longest stage. |
Expulsion | Lasts from full dilation to delivery. |
Placental | Eliminates placenta. Accomplished w/i 15 minutes after birth of infant. |
Reasons for a Cesarean Section | Previous C-section. Deformes or male-like pelvis. Placenta previa-covers cervix. Placenta abruption-detaches before baby is born. Emergency. Atypical presentation of neonate. |
Neonate Presentations | Typical: Cranial end first. Baby faces mother's posterior side. Atypical: Back presentation: baby faces mother's anterior side. Breach: baby's caudal end is first. |