Flashcards in Chapter 20 Deck (44):
The cells of a blastocyst that give rise to the body of the developing offspring constitute the
inner cell mass.
The placental membrane is composed of
a DOUBLE layer of epithelial cells.
The ductus venosus is a fetal vessel that functions to transport blood from the umbilical vein to the
INFERIOR vena cava.
The foramen ovale is an opening that allows fetal blood to pass from the
1. RIGHT ATRIUM to the 2. LEFT ATRIUM
The fetal blood that passes through the ductus venosus is relatively
HIGH in BOTH oxygen and nutrients.
As a result of the foramen ovale, blood is allowed to bypass the
The ductus arteriosus allows fetal blood to move from the
1. pulmonary trunk into the 2. aorta.
Which of the following provides the main source of energy for a newborn during its first few days?
After birth, the foramen ovale is closed as a result of
INCREASING PRESSURE in the LEFT atrium.
Following birth, bradykinin is released from the newborn's lungs in response to
an INCREASING concentration of oxygen in aortic blood.
Which of the following is not a characteristic of childhood?
becoming reproductively functional
The placenta is composed of tissues from the
mother AND embryo.
A major difference between fetal blood flow and adult blood flow is that in the fetus the
INFERIOR VENA CAVA contains blood HIGH in oxygen.
Which of the following adult structures is not derived from the same primary germ layer as the others?
The external genitalia of the fetus can be distinguished as male or female by which of the following periods after fertilization?
about 12 weeks
Which of the following combinations would be needed to cause the development of dizygotic twins?
1. TWO egg cells and 2. TWO sperm cells
Most commonly, a blastocyst becomes implanted in the uterine
UPPER POSTERIOR wall
The placenta synthesizes progesterone from
Teratogens are substances that
cause congenital malformations.
Following birth, the infant's metabolic rate
INCREASES and its oxygen consumption INCREASES.
A blastomere is a _____ and a blastocyst is _____ .
cell produced by cleavage;
A HOLLOW BALL OF CELLS
The inner cell mass within a blastocyst is significant in that it
gives rise to the embryo.
The implantation of the blastocyst results from
ENZYMES DIGESTING THE ENDOMETRIUM around the blastocyst.
Which of the following is not a function of hCG?
It stimulates the release of enzymes that enable the blastocyst to implant into the endometrium.
During the embryonic stage, the primary germ layers develop from the
The major body part(s) derived from ectoderm is/are
nervous system and skin.
The major body parts derived from mesoderm are the
muscle tissue, bone tissue, and bone marrow.
The functions of the placenta are to allow
OXYGEN AND NUTRIENTS to diffuse from maternal blood through the placental membrane into the embryo.
The chorion is the _____ and the amnion is the _____.
OUTERMOST covering of an embryo and helps form the PLACENTA;
membrane that encircles a developing embryo
The allantois functions to
form blood cells and give rise to the umbilical arteries and vein.
Amniotic fluid functions to
protect the embryo against being jarred by movements of the mother's body.
The yolk sac functions to
form blood cells in early development.
The term newborn refers to the period from birth through _____ , whereas the term infant refers to the period from _____ .
the first four weeks;
the first month to 1 year
The hormones mainly responsible for maintaining the uterine wall during the last 5-6 months of pregnancy are
placental ESTROGEN and PROGESTERONE.
The hormone oxytocin aids the birth process by stimulating
uterine wall contractions.
An ectopic pregnancy occurs when an embryo begins development
OUTSIDE the uterus.
The hormone commonly measured in a pregnancy test is
The major hormonal changes that occur in the maternal body during pregnancy are
placental tissues secrete high amounts of estrogen and progesterone.
The implantation of an embryo is aided by
digestive enzymes that the embryo secretes.
The fetal stage of development begins at
the end of the eighth week.
The ductus arteriosus allows fetal blood to
bypass the lungs.
After birth, the ductus arteriosus constricts and becomes the
Some factors that help to __________ are increasing CO2, decreasing pH, decreasing O2, decreasing body temperature, and mechanical stimulation.
stimulate the newborn's first breath