Ch 29 Pregnancy and Heredity
Drugs that lead to birth defects in the formation of the limbs are most damaging when the conceptus is exposed to them during weeks:
4-8 of development, when limbs are undergoing peak development.
Which pathogen (within the mother) is most likely to be transmitted across the placenta?
A blood-borne virus that is present during the sixth week of pregnancy
What is the correct order of structures through which the sperm penetrates during fertilization?
Corona radiata, zona pellucida, oocyte plasma membrane
Blood cells and antibodies pass freely across the placenta.
False
During pregnancy, the levels of CRH and aldosterone within a mother's blood decline.
False
To prepare for the strain of labor and delivery, female reproductive hormones cause ligaments of pelvic joints to tighten.
False
Which is the larger of the sex chromosomes and is more commonly involved in sex-linked inheritance?
The X chromosome
What is expelled during the expulsion stage of labor?
The fetus
Late in pregnancy, levels of estrogen and oxytocin rise.
True
Pregnancy increases a woman's risk of urinary tract infection.
True
Shortly after birth, the foramen ovale of the fetal heart ceases to function as an open pathway for blood.
True
Which structure is an important site for early blood cell formation and is the first of the extraembryonic membranes to form?
Yolk sac
Fertilization typically occurs in the _________, and it restores the _________ number of chromosomes.
ampulla of the uterine tube, diploid
Prolactin is secreted from the ________ gland, and its levels ___________ during pregnancy.
anterior pituitary, increase ten-fold
During pregnancy, the mother's:
cardiac output rises and hematocrit falls.
The fingerlike structures of the placenta that form from its fetal portion are known as:
chorionic villi.
In nonpregnant women, ____________ inhibits secretion of substantial amounts of prolactin.
dopamine
The trimester during which an embryo becomes a fetus is the _________ trimester.
first
The maternal portion of the placenta arises from the:
functional layer of the uterus.
The hormone that signals that fertilization and implantation have taken place is:
human chorionic gonadotropin.
One reason that pregnant women's metabolic rates change is that the placenta secretes:
human chorionic thyrotropin, which stimulates the thyroid gland and raises metabolic rate.
The process by which a blastocyst embeds within the uterine endometrium is known as:
implantation.
Stretching of the cervix causes oxytocin secretion to:
increase
As the fetus develops, the mother's glomerular filtration rate:
increases by about 40%.
Hormonal and neural changes during pregnancy function to facilitate diffusion of gases across the placenta. One way this occurs is by _________ respiration rate, thereby __________ CO2 levels in the blood.
increasing, lowering
During preganancy, estrogen and progesterone from the placenta:
inhibit FSH and LH secretion and thereby arrest ovarian follicle development.
At the 16-cell stage, the conceptus is known as a:
morula.
In a mother who has recently delivered a child, afterpains occur when:
oxytocin triggers uterine contractions.
In the late stages of pregnancy, estrogen stimulates increased:
production of oxytocin receptors in the uterus.
After ovulation, the oocyte:
releases chemotaxic signals to attract sperm to its location.
Although pregnancy sometimes results in frequent urination, the one trimester when this tends to be not as problematic is the:
second.
Human chorionic gonadotropin is secreted from cells of the:
syncytiotrophoblast
By the 4th month of pregnancy, the fundus of the uterus is located inches below the ________ and by the ninth month it is located at the level of the ____________.
umbilicus, xiphoid process
Implantation usually begins at about the end of the first ________ of development.
week