Ch. 28 Pregnancy & Human Development
Implantation of the blastocyst begins __________ after ovulation.
6 to 7 days
The Apgar score range that indicates a healthy baby is __________.
8 to 10 Lower scores indicate one or more physiological problems
What is the most common ART technique?
In vitro fertilization
Which of the following factors is NOT considered to be a teratogen?
Iron
Which of the following statements about the foramen ovale is FALSE?
It allows blood to pass directly from the right atrium into the left ventricle.
What is the function of the hormone hCG (human chorionic gonadotropin)?
It signals the corpus luteum to continue producing estrogen and progesterone to maintain the pregnancy.
All of the following structures are derived from mesoderm EXCEPT __________.
Nails
What hormone causes the letdown reflex?
Oxytocin
Which maternally derived hormone induces and controls labor via a positive feedback mechanism?
Oxytocin
__________ and __________ are both hormones and powerful uterine muscle stimulants that cause contractions to become more frequent and more vigorous.
Oxytocin; prostaglandins
____ refers to events that occur from the time of fertilization (conception) until the infant is born.
Pregnancy
What chemical is most responsible for triggering true labor?
Prostaglandins trigger true labor
Which of the following occurs 17-20 weeks into pregnancy, during the fetal period?
Quickening occurs.
Which hormone produced by the placenta causes the mother's pubic symphysis to loosen and widen?
Relaxin
What has to happen before ejaculated sperm can penetrate an oocyte?
Sperm must be capacitated and an oocyte's zona pellucida must be eroded by the acrosomal enzymes of many sperm
What property of the lung does surfactant affect, making breathing easier?
Surfactant increases compliance by decreasing the alveolar surface tension of a newborn.
Which extraembryonic membrane provides a path for the embryonic blood vessels to reach the placenta?
The allontis provides the basis of the umbillical cord, which provides a pathway for the embryonic blood vessels to reach the placenta.
What is the function of the amnion?
The amnion helps to maintain a constant temperature for the developing fetus, protection from physical trauma, & prevents adhesion of fetal parts.
Why is the multicellular blastocyst only slightly larger than the single-celled zygote?
The blastocyst only slightly larger than the zygote because there is n o time between divisions so the cells get smaller and smaller.
Amber buys an over the counter pregnancy test to, how will the blastocyst, if present "make itself known"?
The blastocyst secretes the hormone human chronic gonadotropin, which is detectable in urine.
What is the composition of the chorion?
The chorion develops from the trophoblast and a layer of extraembryonic mesoderm.
What is the cortical reaction and what does it accomplish?
The cortical reaction involves the release of enzymes from cortical granules to the oocyte exterior, which accomplishes destruction of the zona pellucida sperm binding receptors and the detachment of any sperm still bound to these receptors. These events ensure monospermy.
What endometrial decidua cooperates with the chorionic villi to from the placenta?
The decidua basilis cooperates with the chorionic villi to form the placenta.
Why does a baby turn as it travels through the birth canal?
The descent of the baby's head follows the widest dimensions of the bony pelvis.
When does the fetal period begin?
The fetal period begins at the end of 8 weeks.
What 2 modifications of the fetal circulation allow most of the blood to bypass the heart.
The foramen ovale & ductus arteriosus allow most of the blood to bypass the heart.
Which of the following occurs eight weeks into pregnancy?
The head of the fetus is nearly as large as the body.
What is the role of the hormone hPL?
The hormone hPL works with estrogen and progesterone to stimulate breast maturation, promotes fetal growth, & exerts a glucose-sparing effect on the mother.
What causes morning sickness?
The increasing levels of female sex hormones and hCG in the mother's blood.
Which of the following does NOT describe a function of trophoblast cells?
The inner layers of trophoblasts lose their plasma membranes and invade the endometrium
What germ layer fives rise to essentially all body tissues except nervous tissue, the epidermis, and mucosae?
The mesoderm
What happens to the special fetal circulatory modifications after birth?
The special fetal circulatory modifications are occluded at birth or shortly thereafter.
Which part of the trophoblast accomplishes implantation?
The synctytiotrophoblast accomplishes implantation.
What is the main function of the trophoblast cells?
The trophoblast cells contribute to the formation of the placenta.
The heart begins to beat in the developing offspring _________
at about 3 ½ weeks
Which sequence shows the correct order of the stages of labor?
dilation, expulsion, placental The dilation stage is the longest period, lasting up to 12 hours on average.
An implantation that takes place in a site other than the uterus is called _______
ectopic
Prolactin causes __________
milk production by the breast tissue
The first major event of organogenesis is __________
neurulation
Sperm are known to bear __________ that respond to chemical stimuli that help them locate the oocyte.
olfactory receptors
During early gastrulation, what structure(s) appear(s) on the dorsal aspect of the embryonic disc and establish(e)s the longitudinal axis of the embryo?
primitive streak
The only 100% effective method of birth control is __________
total abstinence
For successful fertilization to occur, coitus must occur NO more than __________ and NO later than __________.
two days before ovulation; 24 hours after
Which of the following is NOT a function of the placenta?
urine formation
When does the placenta become fully functional?
By the end of the 3rd month of pregnancy.
What is a breech presentation?
Breech presentation is a buttock-first of the baby instead of the head during labor.
The early embryo is flat. What event must occur before organogenesis can occur?
Before organogenesis can occur the embryonic body must fold & undercut to form a tubular embryo.
What causes difficulty breathing that some women experience during pregnancy? What causes the waddling gait?
Difficulty breathing occurs during late pregnancy is because the uterus is pressing against the diaphragm (lungs). The waddling gait is due to the relaxing effect of relaxin on the pelvic ligaments & the pubic symphysis.
__________ occurs when a woman has a deformed or male-like pelvis, resulting in prolonged and difficult labor; this condition can lead to fetal brain damage, ultimately causing cerebral palsy or epilepsy.
Dystocia
Which statement about maternal hormones during pregnancy is accurate?
Estrogen levels increase throughout gestation
T/F Coitus interruptus is among the most effective birth control methods.
False
T/F The ectoderm is the primary germ layer from which the digestive, respiratory, and urogenital systems and the associated glands form.
False
T/F The first major event in organogenesis is gastrulation.
False
Which structure represents the remnants of the atrial fetal shunt?
Fossa ovalis
T/F A weight gain of approximately 13 kg (about 28 lb) usually occurs during pregnancy.
True
T/F An Apgar score of 8 to 10 indicates a healthy baby.
True
T/F By the end of the third month of pregnancy, the placenta is usually fully functional as a nutritive, respiratory, excretory, and endocrine organ.
True
T/F Human chorionic gonadotropin (hCG) levels spike within the first two months of pregnancy and then sharply decline by four months.
True
Which of the following does NOT prevent polyspermy?
a decrease in zonal inhibiting proteins
In humans, the extraembryonic membrane that composes the structural base for the umbilical cord is the __________.
allantois
Implantation is completed after the _______
blastocyst is entirely surrounded by endometrium
Which of the following structures is/are formed from ectodermal tissues?
brain
The function of the ductus arteriosus is to _____
bypass the pulmonary circuit
The outermost extraembryonic membrane is the ____
chorion
The disc-shaped placenta is formed from the __________
chronic villi and the decidua basalis
After fertilization, the zygote goes through a rapid period of cell divisions called?
cleavage
Which of the following is NOT a common metabolic/physiological change that occurs in pregnant women?
decreased blood pressure
The development of the primary germ layers is called ________
gastrulation
The process of implantation generally begins __________ and is usually completed by __________.
six to seven days after ovulation; the twelfth day after ovulation
Meconium is ________
sloughed-off epithelial cells, bile, and other substances
