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BIO202-CH28-Preg&Dev
BIO202 - Ch 28 - Pregnancy & Development - Marieb/Hoehn - RioSalado - AZ
| Question | Answer |
|---|---|
| Conceptus | Developing offspring during pregnancy |
| gestation period | Last menstral period to birth - 280 days |
| embryonic period | fertilization to week 8 |
| fetal period | week 9 to birth |
| Sperm fertilizes the __ oocyte. | ovulated secondary oocyte |
| Fertilized egg | zygote - first cell of new individuals |
| What capacitates a sperm so it can fertilize? | Cervical mucus, uterus, uterine tube & secretions of female tract - removes cholesterol of acrosomal membrane. |
| Ovulated oocyte surrounded by? | Corona radiata & zona pellucida - both must be reached by sperm. |
| Sperm receptor on egg. | ZP3 glycoprotein in zona pellucida. |
| Acrosomal reaction | Breakdown of acrosomal membrane & plasma membrane to release acrosomal enzymes to digest hole in zona pellucida. |
| What occurs to block polyspermy? | A corticle reaction - calcium surge that spills enzymes - zonal inhibiting proteins (ZIPs) - that destroy sperm receptors & prevent further sperm entry. |
| What do sperm lose when it enters oocyte? | Tail, midpiece, & centrosome in midpiece that holds microtubules. |
| What prompts secondary oocyte to complete meiosis 2? | Calcium surge due to sperm penetration - forms ovum nubleus to 2nd polar body. |
| Female pronucleus | Ovum nubleus after penetration of ovum & awaits fusion with male pronucleus. |
| When is the true moment of fertilization? | When female pronucleus & male pronucleus combine as their membranes rupture & their chromosomes are released - zygote formed. |
| cleavage | Phase of rapid miotic cell division in zygote without intervening growth periods - blastocyst formed - 2 identical cells. |
| morula | At 72 hours - berry-shaped cluster of 16+ cells |
| Why is multicellular blastocyte only slightly larger than single-celled zygote? | Virtually no growth occurs between successive divisions of cleavage. |
| Trophoblast cells help form? | placenta |
| Inner cell mast in blastocyst becomes? | Embryonic disk & then embryo |
| What surging hormones in blood repare endometrium for implantation? | Estrogens & progesterone |
| Which cells of blastocyte adheres to endometrium? | Trophoblast cells overlying inner cell mass. |
| Period of implantation | 5 days & complete usually by 12th day after ovulation. |
| Viability of corpus luteum is maintained by __. | hCG - human chorionic gonadotropin - LH-like hormone secreted by trophoblast cells. Keeps corpus luteum secreting progesterone & estrogen. |
| What do pregnancy tests test for? | Antibody tests that detect hCG. |
| Placentation | Placenta formation - chorion -> chorionic villi + decidua basalis = placenta. |
| What does placenta do? | Nutritive, respiratory, excretory, & endocrine organ. |
| What are the mother/embryo barriers? | Chorionic villi & endothelium of embryonic capillaries. |
| Levels of estrogen & progesterone __ during pregnancy, while hCG levels __. | increase-decline |
| The blastocyst becomes a __. | gastrula - 3 primary germ layers form & extraembryonic membranes develop. |
| Extraembryonic membranes | amnion, yolk sac, allantos, & chorion |
| amnion | Amniotic sac that fills with amniotic fluid & surrounds embryo. |
| yolk sac | Primitive gut - hangs from ventral surface of embryo - forms digestive tube & earliest blood cells & vessels. |
| allantois | Structural base for umbilical cord - links embryo to placenta & becomes part of urinary bladder. |
| The chorion encloses __. | embryonic body & all other membranes. |
| Primary germ layers. | ectoderm, mesoderm, & endoderm |
| gastrulation | 2-layered embryonic disk - transforms into 3-layered embryo - week 3 |
| The primitive streak establishes __. | the longitudinal axis of embryo. |
| Most inferior germ layer | endoderm |
| First axial support of embryo | notochord - rod of mesodermal cells |
| Ectoderm forms? | "Outer skin" - nervous system & epidermis. |
| Endoderm forms? | "Inner skin" - epithelial lining of digestive, respiration, & urogenital system, & glands. |
| Mesoderm forms? | Skeleton & muscles of body. |
| Organogenesis | Formation of body organs & systems. |
| 1st major even of organogenesis | Neurulation - ectoderm that produces brain & spinal cord over notochord. |
| Anterior end of neural tube becomes? | Brain & rest becomes spinal cord. |
| somites | Paired mesodermal blocks that hug notochord on either side - 40 pairs - becomes verterbra & rib, dorsal dermis & muscles of neck, trunk, & limbs. |
| Splanchnic | Mesenchymal cells form heart, blood vessels, & CT of body. |
| Somatic mesoderm | Form ventral dermis, parietal serosa, limbs, bones, ligaments, & limb dermis. |
| coelom | Ventral body cavity - forms it from lateral mesodermal layers. |
| ductus venosus | Venous shunt that bypasses liver sinusoids. |
| Fetus' hepatic veins & ductus venosus empty __. | Into the inferior vena cava where placental blood mixes with deoxygenated blood. |
| Where does fetus' vena cava convey blood? | R-atrium |
| Foramen ovale | Allows fetal blood to pass from right atrium to left atrium - opening in interartrial septum. |
| ductus arteriosus | Transfers blood to aorta & bypasses pulmonary circuit. |
| teratogens | Factors that produce congenital abnormalities - alcohol, drugs, measles. |
| Chadwick's sign | Vagina develops purplish hue as it engorges with blood. |
| chloasma | mask of pregnancy - pigmentation |
| parturition | birth - 280 days from last menstral period |
| What hormone events induce labor? | Estrogen from placenta induces oxytocin receptors on uterus (myometrial cells) - this antagonizes progesterone - fetal cells produce oxytocin & placenta releases prostaglandins - stimulates muscle contraction - positive feedback mech. |
| Both __ & __ are essential for initiating labor. | Oxytocin & prostaglandins |
| Vertex presentation | head-first |
| dystocia | difficult birth due to malformed pelvis. |
| 5 Apgar signs | heart rate, respiration, color, muscle tone, & reflexes. |
| What causes baby's first breath? | CO2 build up - acidosis - excites respiratory centers in brain. |
| What hormone causes let-down reflex? | oxytocin |
Created by:
Ladystorm
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