NURS 3334 Exam 2 Study Guide- Questions and Answers

hcG human chorionic gonadoptropin glycoprotein maintains corpus luteum - remaining cells of old follicle that has released ovum) hPL (human placental lactogen) // hCS (human chorionic somatomammotropin) promotes fetal growth steroidogenesis (progesterone and estrogen) by 7 weeks - takes over for corpus luteum Growth factors (hormones) regulate cell growth and differentiation Anatomy of placenta - maternal - fetal maternal - decidua basalis fetal - chorionic villi Placenta developmental stages 1. trophoblast cells of chorionic villi form spaces in tissue of decidua basalis 2. spaces fill with maternal blood, chorionic villi grow into spaces at 17 days: maternal-placental-embryonic circulation complete then embryonic heart beats by 4th week - embryonic maternal metabolic exchange occurs Materials moved by transport: - simple diffusion - facilitated diffusion - active transport - pinocytosis - simple diffusion: O2, electrolytes, drugs - facilitated diffusion: glucose, sometimes O2 - active transport: amino acids, iron, water soluble vitamins - pinocytosis: immunoglobulins (IgG) Umbilical cord 2 arteries, 1 vein 4 vessels: - one vein atrophies by 6 weeks - occasionally one artery also atrophies (=2 vessel cord, anomalies) develops from amnion, connective tissue surrounds blood vessels = wharton's jelly Umbilical cord Wharton's Jelly collagen, muscle, mucopolysaccharides helps protect vessel from compression Placental Fetal Blood Flow / Exchange Blood flow: 500 mL/min Exchange: - Deoxygenated fetal blood through 2 umbilical arteries to capillaries of villi - Then O2 rich blood flows back through umbilical vein to fetus Maternal and fetal circulation separated Separated by layers of tissue called: "placental membrane" or "placental barrier" Embryonic membranes able to stretch and resist rupture as fetus grows - protects and supports fetus as it grows - amnion - chorion Amnion interior, thin, friable - passively pushed against thicker chorion - can rupture causing shreds - may wrap around and amputate fetal parts - space between amniotic membrane and embryo is amniotic cavity Chorion thicker, tough, continuous with chorionic plate, forms base of placenta Amniotic fluid volume gradually increases 98% H2O - fetal urine major source last half pregnancy volume gradually increases - 7 mL at 8 weeks - 800 mL at term - peaks at approx 1000 mL 2 weeks before delivery Amniotic fluid usefulness allows symmetric fetal growth constant temp/pressure cushion fetus