ExamName___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Milk ejection or letdown reflex is stimulated by which of the following hormones associated with 1) pregnancy? A) inhibin B) gonadotropin C) prolactin D) oxytocin Answer: D Explanation: A) B) C) D) 2) Onset of labor may be a result of all of the following factors except ________. 2) A) aspirin and similar drugs B) secretion of oxytocin C) contraction-related increased emotional and physical stress D) high estrogen levels Answer: A Explanation: A) B) C) D) 3) Relaxin is a hormone produced by the placenta and ovaries. The function of this hormone is to 3) ________. A) prevent morning sickness B) relax the pubic symphysis C) block the pain of childbirth D) ensure the implantation of the blastula Answer: B Explanation: A) B) C) D) 4) The dorsal surface cells of the inner cell mass form ________. 4) A) the primitive streak B) the notochord C) a structure called the embryonic disc D) one of the fetal membranes Answer: A Explanation: A) B) C) D) 1 5) Estrogen and progesterone maintain the integrity of the uterine lining and prepare the mammary 5) glands to secrete milk. Which of the following structures makes this possible during the first three months of pregnancy? A) the chorion B) the amnion C) corona radiata D) corpus luteum Answer: D Explanation: A) B) C) D) 6) Which of the following statements about the events of fertilization is not true? 6) A) The secondary oocyte completes the second meiotic division. B) Proteases and acrosin proteinases of the sperm disperse the cells of the corona radiata of the oocyte. C) The head of the sperm forms the male pronucleus. D) The two pronuclei divide. Answer: D Explanation: A) B) C) D) 7) Neural tissue is formed by the ________. 7) A) ectoderm B) endoderm C) mesoderm D) epiderm Answer: A Explanation: A) B) C) D) 8) Derivatives of the endoderm include ________. 8) A) organs of the urogenital system B) blood, bone marrow, and lymphoid tissue C) synovial membranes of the joints D) epithelium of the respiratory tract Answer: D Explanation: A) B) C) D) 9) The result of polyspermy in humans is ________. 9) A) multiple births B) interruption of meiosis C) a nonfunctional zygote D) mitotic insufficiency Answer: C Explanation: A) B) C) D) 2 10) Which hormone is not produced by the placenta? 10) A) human placental lactogen B) inhibin C) human chorionic thyrotropin D) relaxin Answer: B Explanation: A) B) C) D) 11) Initially, the implanted embryo obtains its nutrition by ________. 11) A) the blood supply of the placenta B) simple diffusion of nutrients from the uterine secretions C) nutrient stores in the embryonic cells D) digestion of endometrial cells Answer: D Explanation: A) B) C) D) 12) Derivatives of the ectoderm include ________. 12) A) serosae of the ventral body cavity B) connective tissues C) epithelium of the reproductive tract D) epithelium of the pineal and pituitary glands Answer: D Explanation: A) B) C) D) 13) Proteases and acrosin are enzymes. How do they function in reproduction? 13) A) They act to break down the protective barriers around the egg, allowing the sperm to penetrate. B) They direct the sperm to the egg through chemical messengers. C) Their function is unknown. D) They neutralize the mucous secretions of the uterine mucosa. Answer: A Explanation: A) B) C) D) 14) The trophoblast is mostly responsible for forming the ________. 14) A) archenteron B) allantois C) placental tissue D) lining of the endometrium Answer: C Explanation: A) B) C) D) 3 15) Which of the following is not a germ layer? 15) A) mesoderm B) endoderm C) ectoderm D) epiderm Answer: D Explanation: A) B) C) D) 16) Shortly after implantation ________. 16) A) the embryo gastrulates (within 3 days) B) myometrical cells cover and seal off the blastocyst C) the trophoblast forms two distinct layers D) maternal blood sinuses bathe the inner cell mass Answer: C Explanation: A) B) C) D) 17) At which stage of labor is the "afterbirth" expelled? 17) A) full dilation B) expulsion C) placental D) dystocia Answer: C Explanation: A) B) C) D) 18) Developmental events during weeks 9-12 include ________. 18) A) sex readily detected from the genitals B) head larger than body C) the cardiovascular system becoming fully functional D) fetal position assumed Answer: A Explanation: A) B) C) D) 19) Cells on the dorsal surface of the two-layered embryonic disc migrate to form a raised groove 19) known as the ________. A) germ cell formation B) amnion formation C) primitive streak D) blastocyst Answer: C Explanation: A) B) C) D) 4 20) The cardiovascular system of a newborn must be adjusted after the infant takes its first breath. 20) Which of the following is also true? A) The ductus arteriosus constricts and is converted to the ligamentum arteriosum. B) The ductus venosus is disconnected at the severing of the umbilical cord and all visceral blood goes into the vena cava. C) The foramen ovale between the atria of the fetal heart closes at the moment of birth. D) The urinary system is activated at birth. Answer: A Explanation: A) B) C) D) 21) The umbilical arteries carry ________. 21) A) waste products to the placenta B) oxygen and metabolic wastes to the placenta C) oxygen and food to the fetus D) oxygen and waste products to the fetus Answer: A Explanation: A) B) C) D) 22) During which stage of labor is the fetus delivered? 22) A) gastrula stage B) dilation stage C) expulsion stage D) placental stage Answer: C Explanation: A) B) C) D) 23) The correct sequence of preembryonic structures is ________. 23) A) zygote, blastocyst, morula B) blastocyst, morula, zygote C) zygote, morula, blastocyst D) morula, zygote, blastocyst Answer: C Explanation: A) B) C) D) 24) Hormones concerned with events of lactation include ________. 24) A) oxytocin B) estrogen C) hCG D) progesterone Answer: A Explanation: A) B) C) D) 5 25) Muscle tissue is formed by the ________. 25) A) ectoderm B) endoderm C) mesoderm D) epiderm Answer: C Explanation: A) B) C) D) 26) Select the correct statement about fertilization. 26) A) Once inside the uterus, most sperm cells are protected and remain viable. B) If estrogen is present, the pathway through the cervical opening is blocked from sperm entry. C) Both spermatozoa and the ovulated secondary oocyte remain viable for about 72 hours in the female reproductive tract. D) Millions of sperm cells are destroyed by the vagina's acidic environment. Answer: D Explanation: A) B) C) D) 27) Implantation of the blastocyst is the result of all of the following except ________. 27) A) adherence of the trophoblast cells to the endometrium B) settling of the blastocyst onto the prepared uterine lining C) proteolytic enzymes produced by the trophoblast cells D) phagocytosis by the trophoblast cells Answer: D Explanation: A) B) C) D) 28) Which of the following is a highly unlikely method of producing a child? 28) A) in vitro fertilization B) embryo transfer C) ectopic implantation D) gamete intrafallopian transfer Answer: C Explanation: A) B) C) D) 29) It is impossible for sperm to be functional (able to fertilize the egg) until after ________. 29) A) they have been stored in the uterus for several days B) they undergo capacitation C) they become spermatids D) the tail disappears Answer: B Explanation: A) B) C) D) 6 30) Cleavage as part of embryonic development is distinctive because it involves ________. 30) A) splitting the cell into two separate cells B) meiosis C) the fusion of gametes D) cell division by mitosis with little or no growth between successive divisions Answer: D Explanation: A) B) C) D) 31) Sperm move to the uterine tube through uterine contractions and the energy of their own flagella. 31) What other factor is involved in sperm movement? A) the cilia on the apex of the cells lining the endometrium B) hormonal attraction to the ova C) reverse peristalsis of the uterus and uterine tubes D) the increased temperature in the vagina, which stimulates sperm motility Answer: C Explanation: A) B) C) D) 32) Implantation involves ________. 32) A) embedding of the blastocyst in the uterine wall B) formation of germ layers C) fusion of egg and sperm D) placenta completion Answer: A Explanation: A) B) C) D) 33) Which of the following is not a correct matching of a fetal structure with what it becomes at birth? 33) A) ductus venosus ligamentum venosum B) ductus arteriosus ligamentum teres C) umbilical arteries medial umbilical ligament D) foramen ovale fossa ovalis Answer: B Explanation: A) B) C) D) 7 34) Which hormone maintains the viability of the corpus luteum? 34) A) human placental lactogen B) estrogen C) progesterone D) human chorionic gonadotropin Answer: D Explanation: A) B) C) D) 35) Select the correct statement about the special fetal blood vessels. 35) A) The umbilical vein becomes the ligamentum teres. B) The distal parts of the umbilical arteries form the superior vesical arteries. C) The fossa ovalis becomes the foramen ovale. D) The hepatic portal vein forms from the umbilical artery. Answer: A Explanation: A) B) C) D) 36) The placenta, a vitally important metabolic organ, is made up of a contribution from mother and 36) fetus. Which portion is from the fetus? A) umbilicus B) yolk sac C) amnion D) chorion Answer: D Explanation: A) B) C) D) 37) The decidua basalis is ________. 37) A) located between the developing embryo and the myometrium B) not a maternal contribution to the placenta C) destined to remain in the uterus after the birth of the infant D) the tissue that surrounds the uterine cavity face of the implanted embryo Answer: A Explanation: A) B) C) D) 38) The formation of endodermal and ectodermal germ layers occurs at ________. 38) A) cleavage B) blastula formation C) fertilization D) gastrulation Answer: D Explanation: A) B) C) D) 8 39) Which of the following is not usually considered a teratogen? 39) A) wine B) thalidomide C) aspirin D) German measles Answer: C Explanation: A) B) C) D) 40) Derivatives of the mesoderm include ________. 40) A) glandular derivatives of the digestive tract B) all nervous tissue C) epithelium of the digestive tract D) endothelium of blood and lymph vessels Answer: D Explanation: A) B) C) D) 41) Which of the following is not assessed as part of the Apgar score? 41) A) muscle tone B) heart rate C) respiration D) temperature Answer: D Explanation: A) B) C) D) 42) Which of the following is true in reference to what may pass through the placental barriers? 42) A) nutrients, respiratory gases, wastes, and alcohol B) respiratory gases, hormones, nutrients, and blood cells C) nutrients and respiratory gases only D) hormones, blood cells, and nutrients Answer: A Explanation: A) B) C) D) 43) Which of the choices below occurs if fertilization of the ovum occurs and implantation takes place? 43) A) The corpus luteum degenerates and becomes the corpus albicans. B) The corpus luteum is maintained until the placenta takes over its hormone-producing functions. C) Increased levels of FSH will be produced. D) The ovarian cycle begins. Answer: B Explanation: A) B) C) D) 9 SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 44) Describe the events allowing monospermy. 44) Answer: A sperm entering the oocyte causes ionic calcium to be released into the oocyte cytoplasm, activating the oocyte and preparing it for cell division. This also causes the cortical granules to spill their contents into the extracellular space beneath the zona pellucida. Enzymes from the cortical granulus destroy sperm receptors, preventing further sperm entry. This spilled material binds with water, and as it swells, detaches all sperm still in contact with the oocyte membrane. Explanation: 45) Neural tissue develops from the ________. 45) Answer: ectoderm Explanation: Figure 28.2 Using Figure 28.2, match the following: 46) Extraembryonic membrane that develops from the trophoblast and some extraembryonic 46) mesoderm, and forms part of the placenta. Answer: Chorionic villus Explanation: 47) The first "milk" the mother produces is called ________. 47) Answer: colostrum Explanation: 48) At what time in the pregnancy is the placenta fully prepared to fulfill the needs of the 48) developing fetus? Answer: The placenta is fully formed and functional as a nutritive, respiratory, excretory, and endocrine organ by the end of the third month of pregnancy. Explanation: 10 49) The ________ stage of development is the first in which all three germ layers of tissue are 49) evident. Answer: gastrula Explanation: Figure 28.1 Using Figure 28.1, match the following: 50) Stomach. 50) Answer: C Explanation: 51) The ________ cells of the blastocyst will take part in placental formation. 51) Answer: trophoblast Explanation: 52) After the egg is fertilized, it is called a(n) ________. 52) Answer: zygote Explanation: 53) What embryonic structure is the structural base for the umbilical cord? 53) Answer: allantois Explanation: 54) As the newborn suckles, the mother's pituitary produces ________ to assist in producing 54) milk. Answer: prolactin Explanation: 11 55) Explain what triggers a baby’s first breath. 55) Answer: A buildup of carbon dioxide in the baby’s blood once the carbon dioxide is not being removed by the placenta causes acidosis. This excites respiratory control centers in the baby’s brain and triggers the first inspiration. Explanation: Figure 28.2 Using Figure 28.2, match the following: 56) Protective water-filled sac surrounding the embryo. 56) Answer: Amnion Explanation: 57) List four factors that help to precipitate parturition. 57) Answer: Four factors that help to precipitate parturition include: (1) estrogen peaks to its highest levels in the mother's blood, causing irregular uterine contractions due to oxytocin and negation of progesterone's influence on the uterine muscle; (2) prostaglandins are stimulated by the increase in oxytocin to act as uterine muscle stimulants; (3) increasing emotional and physical stressors activate the mother’s hypothalamus, which signals oxytocin release; and (4) certain cells of the fetus begin to produce oxytocin, which in turn acts on the placenta, stimulating production and release of prostaglandins. Explanation: 12 Figure 28.1 Using Figure 28.1, match the following: 58) Pancreas. 58) Answer: E Explanation: 59) Esophagus. 59) Answer: A Explanation: 60) ________ is a tissue with star-shaped cells that are free to migrate widely throughout the 60) embryo. Answer: Mesenchyme Explanation: 61) The first axial support for the embryo is called the ________. 61) Answer: notochord Explanation: 62) Define Braxton-Hicks contractions. 62) Answer: Braxton-Hicks contractions are the weak, irregular uterine contractions resulting from the increase in estrogen production. Estrogen causes oxytocin receptors to form on the myometrial cells of the uterus and antagonizes progesterone's quieting influence on the uterine muscle. As a result, the myometrium becomes increasingly irritable, resulting in weak, irregular contractions. Explanation: 13 63) Describe the events of the oocyte from sperm penetration to first cleavage. 63) Answer: After sperm penetration, the oocyte completes meiosis II and releases the second polar body. The two nuclei swell into pronuclei and join each other to form a zygote. The cell then undergoes its first mitosis and cell division to form two daughter cells. Explanation: 64) Which cells invade the endometrium, digesting the uterine cells they contact, so that 64) implantation of the blastocyst can occur? Answer: syncytial trophoblast cells Explanation: Figure 28.1 Using Figure 28.1, match the following: 65) Liver. 65) Answer: D Explanation: 66) Briefly describe the physiological changes occurring in the mother during pregnancy. 66) Answer: Many women suffer nausea until their systems become adjusted to elevated levels of estrogen and progesterone. Heartburn is common due to displacement of the esophagus and crowding of the stomach by the growing fetus in the uterus. Additional wastes from fetal metabolism cause the production of more urine. Due to pressure on the bladder by the uterus, urination is more frequent. Tidal volume increases during pregnancy, as does respiratory rate. Residual volume decreases and many women exhibit dyspnea. Total body water rises, acting as a safeguard against blood loss during birth. Blood volume increases, blood pressure and pulse rise, and cardiac output increases. Explanation: 14 67) How are the metabolic needs of the implanted embryo provided for? 67) Answer: Initially, the implanted embryo obtains nutrition by digesting the endometrial cells, but by the second month, the placenta is providing all the nourishment and oxygen the embryo requires. The placenta is also responsible for disposing of embryonic metabolic wastes. Explanation: Figure 28.2 Using Figure 28.2, match the following: 68) Site of early blood cell production, and forms part of the gut (digestive tube). 68) Answer: Yolk sac Explanation: 69) When do we begin to call the developing individual a fetus rather than an embryo? 69) Answer: We begin to call the developing individual a fetus at the beginning of the ninth week. Explanation: 70) The act of giving birth is called ________. 70) Answer: parturition Explanation: 71) Briefly describe the events leading to the implantation of the blastocyst in the uterus, 71) including how it is nourished. Answer: The blastocyst floats freely in the uterine cavity for three or four days, during which time it is nourished by uterine secretions. Six days after ovulation, implantation begins. The trophoblast determines the readiness of the endometrium for implantation. If the mucosa is prepared for implantation, the blastocyst becomes embedded high in the uterus. Explanation: 15 Figure 28.2 Using Figure 28.2, match the following: 72) The part of the endometrium that surrounds the uterine cavity face of the implanted 72) embryo. Answer: Decidua capsularis Explanation: 73) The part of the endometrium destined to be a part of the placenta. 73) Answer: Decidua basalis Explanation: 16 Figure 28.1 Using Figure 28.1, match the following: 74) Trachea. 74) Answer: B Explanation: TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 75) Of the three germ layers, the mesoderm forms the most body parts. 75) Answer: True False Explanation: 76) Fertilization occurs while the egg is still in the ovarian follicle. 76) Answer: True False Explanation: 77) By 72 hours after fertilization, the egg has divided into more than 160 cells and is called the morula. 77) Answer: True False Explanation: 78) Freshly deposited sperm are not capable of penetrating an oocyte. 78) Answer: True False Explanation: 79) The period from fertilization through week eight is called the embryonic period. 79) Answer: True False Explanation: 17 80) In fetal circulation, one way in which blood bypasses the nonaerated lungs is by way of the 80) foramen ovale. Answer: True False Explanation: 81) A zygote is usually formed within the uterus. 81) Answer: True False Explanation: 82) The embryonic stage lasts until the end of the eighth week. 82) Answer: True False Explanation: 83) Implantation begins six to seven days after ovulation. 83) Answer: True False Explanation: 84) A blastocyst is a hollow ball of cells, while the morula is a solid ball of cells. 84) Answer: True False Explanation: 85) The embryo is directly enclosed in and protected by the amnion. 85) Answer: True False Explanation: 86) Surfactant production in premature infants is rarely a factor in providing normal respiratory 86) activity. Answer: True False Explanation: 87) A pregnancy test involves antibodies that detect GH levels in a woman's blood or urine. 87) Answer: True False Explanation: 88) Human placental lactogen initiates labor. 88) Answer: True False Explanation: 89) The placenta and its attached fetal membranes are collectively called the afterbirth. 89) Answer: True False Explanation: 90) A pregnant woman urinates more often than usual because the uterus compresses the bladder, and 90) she must also dispose of fetal metabolic wastes. Answer: True False Explanation: 91) Conceptus is a term used to describe the developing human offspring. 91) Answer: True False Explanation: 18 92) An episiotomy is an incision made to widen the vaginal orifice, aiding fetal expulsion. 92) Answer: True False Explanation: 93) The body systems of the developing embryo are present in at least rudimentary form at eight 93) weeks. Answer: True False Explanation: 94) The "fluid-filled, hollow ball of cells" stage of development is the blastocyst. 94) Answer: True False Explanation: MATCHING. Choose the item in column 2 that best matches each item in column 1. Match the following: 95) Leads to the development of a morula A) Cleavage 95) and then a blastocyst. Answer: A B) Capacitation 96) Leads to the establishment of the three C) Gastrulation 96) primary germ layers. Answer: C D) Implantation 97) Embedding of the blastocyst in the E) Fertilization 97) uterine wall. Answer: D 98) Leads to enhancement of sperm 98) motilityand increasing membrane fragility to enable enzyme release from acrosomes. Answer: B 99) Leads to the formation of the first cell 99) of the new individual. Answer: E ESSAY. Write your answer in the space provided or on a separate sheet of paper. 100) The patient is in her first trimester of pregnancy. She complains of feeling nauseated and has vomited on occasion. She tells the nurse that she did not have this with her first pregnancy. She asks the nurse, "What is causing this and when will it end?" How should the nurse respond? Answer: The nurse should explain that nausea is a common occurrence during the first trimester of pregnancy caused by elevated levels of progesterone and estrogen, and that the nausea should end once her body adjusts to the increased hormone levels. 19 101) A mother who has been nursing her infant for over seven months is beginning to have problems throughout the day with nausea. Is there a connection? Answer: The mother was not taking birth control pills because she assumed that she could not get pregnant while nursing. Under normal conditions that would be true, but after a few months some women do begin to ovulate again. This mother is probably pregnant again. 102) A 28-year-old woman has been in the first stage of labor for several hours. Her uterine contractions are weak, and her labor is not progressing normally. Because the woman insists upon a vaginal delivery, the physician orders that pitocin (a synthetic oxytocin) be infused. What will be the effect of pitocin? What is the normal mechanism by which oxytocin acts to promote birth? Answer: Pitocin will act on the placenta, stimulating production and release of prostaglandins. The pitocin and prostaglandins are powerful uterine muscle stimulants. Oxytocin normally causes frequent and vigorous contractions of the uterine wall. 103) A 30-year-old woman is admitted to the emergency room. Her husband, who rode in the ambulance with her, said that she had suddenly complained of severe pain in the right iliac region of her abdomen and then had collapsed. Upon examination, she was shown to have signs of internal hemorrhage and her abdominal muscles were rigid. Her menstrual history revealed that she had missed her last menstrual period. A diagnosis of ruptured tubal, or ectopic, pregnancy was made and surgery scheduled. What is an ectopic pregnancy, and why is it problematic? Answer: An ectopic pregnancy occurs when the embryo implants in any site other than the uterus. In a tubal pregnancy the embryo tries to implant in the uterine tube. It is unable to establish a placenta or accommodate growth, and the uterine tube ruptures. 104) Mrs. Phang, eight months pregnant with her first child, makes an appointment with her obstetrician to investigate the cause of vaginal bleeding. Because it is actually more "spotting" than frank bleeding, and painless, she is becoming worried. Ultrasound visualization of her abdomen shows that the placenta is formed across the internal os of the cervix, and she is ordered to her bed for the remainder of the pregnancy. What name is given to Mrs. Phang's condition? Why is it an extremely serious condition? Why was she ordered to have complete bed rest for the remainder of her pregnancy? Answer: Mrs. Phang's condition is called placenta previa. It is an extremely serious condition because as the uterus and cervix stretch, tearing of the placenta may occur. She was ordered to have complete bed rest to keep physical activity at a minimum so that the placenta would not tear away. 105) The lactation nurse visits a first-time mother six hours after her delivery of a healthy 8-pound boy. The patient is giving the baby boy a bottle of sugar water. She tells the lactation nurse that she does not seem to be producing milk. What should the nurse say to the patient? Answer: The nurse should explain that she won't produce true milk until two to three days later. During this delay, colostrum is produced that contains protein, vitamin A, and minerals and is rich in antibodies that are necessary for the baby. The nurse should explain that continual milk production depends on mechanical stimulation of the nipples, normally provided by the sucking infant. 106) A 19-year-old, single, sexually active college student, who has not used birth control on a regular basis, is in her first trimester of pregnancy. She is at the OB/GYN clinic for her first prenatal visit. In assessing her nutrition, the nurse discovers that the patient drinks heavily on a regular basis. She also states she does not like milk. What information should the nurse give the patient regarding nutrition? Answer: Because many potentially harmful substances can cross placental barriers and enter the fetal blood, the nurse should instruct the patient to not drink alcohol. The nurse should warn the patient that alcohol can cause serious permanent damage to the fetus. The nurse should inform the patient to take multivitamins containing folic acid to reduce the risk of birth defects. The patient should increase her daily calorie intake by 300 calories to sustain proper fetal growth. 20 Answer Key Testname: C28 1) D 2) A 3) B 4) A 5) D 6) D 7) A 8) D 9) C 10) B 11) D 12) D 13) A 14) C 15) D 16) C 17) C 18) A 19) C 20) A 21) A 22) C 23) C 24) A 25) C 26) D 27) D 28) C 29) B 30) D 31) C 32) A 33) B 34) D 35) A 36) D 37) A 38) D 39) C 40) D 41) D 42) A 43) B 44) A sperm entering the oocyte causes ionic calcium to be released into the oocyte cytoplasm, activating the oocyte and preparing it for cell division. This also causes the cortical granules to spill their contents into the extracellular space beneath the zona pellucida. Enzymes from the cortical granulus destroy sperm receptors, preventing further sperm entry. This spilled material binds with water, and as it swells, detaches all sperm still in contact with the oocyte membrane. 45) ectoderm 46) Chorionic villus 21 Answer Key Testname: C28 47) colostrum 48) The placenta is fully formed and functional as a nutritive, respiratory, excretory, and endocrine organ by the end of the third month of pregnancy. 49) gastrula 50) C 51) trophoblast 52) zygote 53) allantois 54) prolactin 55) A buildup of carbon dioxide in the baby’s blood once the carbon dioxide is not being removed by the placenta causes acidosis. This excites respiratory control centers in the baby’s brain and triggers the first inspiration. 56) Amnion 57) Four factors that help to precipitate parturition include: (1) estrogen peaks to its highest levels in the mother's blood, causing irregular uterine contractions due to oxytocin and negation of progesterone's influence on the uterine muscle; (2) prostaglandins are stimulated by the increase in oxytocin to act as uterine muscle stimulants; (3) increasing emotional and physical stressors activate the mother’s hypothalamus, which signals oxytocin release; and (4) certain cells of the fetus begin to produce oxytocin, which in turn acts on the placenta, stimulating production and release of prostaglandins. 58) E 59) A 60) Mesenchyme 61) notochord 62) Braxton-Hicks contractions are the weak, irregular uterine contractions resulting from the increase in estrogen production. Estrogen causes oxytocin receptors to form on the myometrial cells of the uterus and antagonizes progesterone's quieting influence on the uterine muscle. As a result, the myometrium becomes increasingly irritable, resulting in weak, irregular contractions. 63) After sperm penetration, the oocyte completes meiosis II and releases the second polar body. The two nuclei swell into pronuclei and join each other to form a zygote. The cell then undergoes its first mitosis and cell division to form two daughter cells. 64) syncytial trophoblast cells 65) D 66) Many women suffer nausea until their systems become adjusted to elevated levels of estrogen and progesterone. Heartburn is common due to displacement of the esophagus and crowding of the stomach by the growing fetus in the uterus. Additional wastes from fetal metabolism cause the production of more urine. Due to pressure on the bladder by the uterus, urination is more frequent. Tidal volume increases during pregnancy, as does respiratory rate. Residual volume decreases and many women exhibit dyspnea. Total body water rises, acting as a safeguard against blood loss during birth. Blood volume increases, blood pressure and pulse rise, and cardiac output increases. 67) Initially, the implanted embryo obtains nutrition by digesting the endometrial cells, but by the second month, the placenta is providing all the nourishment and oxygen the embryo requires. The placenta is also responsible for disposing of embryonic metabolic wastes. 68) Yolk sac 69) We begin to call the developing individual a fetus at the beginning of the ninth week. 70) parturition 71) The blastocyst floats freely in the uterine cavity for three or four days, during which time it is nourished by uterine secretions. Six days after ovulation, implantation begins. The trophoblast determines the readiness of the endometrium for implantation. If the mucosa is prepared for implantation, the blastocyst becomes embedded high in the uterus. 72) Decidua capsularis 73) Decidua basalis 74) B 75) TRUE 22 Answer Key Testname: C28 76) FALSE 77) FALSE 78) TRUE 79) TRUE 80) TRUE 81) FALSE 82) TRUE 83) TRUE 84) TRUE 85) TRUE 86) FALSE 87) FALSE 88) FALSE 89) TRUE 90) TRUE 91) TRUE 92) TRUE 93) TRUE 94) TRUE 95) A 96) C 97) D 98) B 99) E 100) The nurse should explain that nausea is a common occurrence during the first trimester of pregnancy caused by elevated levels of progesterone and estrogen, and that the nausea should end once her body adjusts to the increased hormone levels. 101) The mother was not taking birth control pills because she assumed that she could not get pregnant while nursing. Under normal conditions that would be true, but after a few months some women do begin to ovulate again. This mother is probably pregnant again. 102) Pitocin will act on the placenta, stimulating production and release of prostaglandins. The pitocin and prostaglandins are powerful uterine muscle stimulants. Oxytocin normally causes frequent and vigorous contractions of the uterine wall. 103) An ectopic pregnancy occurs when the embryo implants in any site other than the uterus. In a tubal pregnancy the embryo tries to implant in the uterine tube. It is unable to establish a placenta or accommodate growth, and the uterine tube ruptures. 104) Mrs. Phang's condition is called placenta previa. It is an extremely serious condition because as the uterus and cervix stretch, tearing of the placenta may occur. She was ordered to have complete bed rest to keep physical activity at a minimum so that the placenta would not tear away. 105) The nurse should explain that she won't produce true milk until two to three days later. During this delay, colostrum is produced that contains protein, vitamin A, and minerals and is rich in antibodies that are necessary for the baby. The nurse should explain that continual milk production depends on mechanical stimulation of the nipples, normally provided by the sucking infant. 106) Because many potentially harmful substances can cross placental barriers and enter the fetal blood, the nurse should instruct the patient to not drink alcohol. The nurse should warn the patient that alcohol can cause serious permanent damage to the fetus. The nurse should inform the patient to take multivitamins containing folic acid to reduce the risk of birth defects. The patient should increase her daily calorie intake by 300 calories to sustain proper fetal growth. 23