Lsn 29 HW 27.3-27.10
At which day post cleavage does implantation occur?
day 7
Under the influence of the trophoblast, maternal blood vessels in the endometrium
break down and form lacunae
Embryonic and early fetal development occurs in the ___ trimester
first
The extraembryonic membrane that forms the fetal portion of the placenta is the
chorion
In pregnancy, expansion of the uterus results from
hypertrophy of smooth muscle cells
After 3 days, a pre embryo becomes a solid ball of cells known as a
morula
The mesoderm forms
muscle
The ectoderm forms
neural tissues
Stretching of the cervix causes an increase in the blood levels of
oxytocin
During gestation, contraction of the myometrium is inhibited by ___, produced by the placenta.
progesterone
During implantation, the
syncytial trophoblast erodes a path through the endometrium
Regarding the factors of true labor
the fetal pituitary releases oxytocin in response to estrogens
During gastrulation,
three germ layers are formed
Deoxygenated blood is carried to the placenta by the
umbilical arteries
The extraembryonic membrane that forms blood cells is the
yolk sac
The embryonic heart starts beating as blood begins to flow through chorionic vessels at approx ___ weeks.
"week 2" week 3 right?
Progesterone calms the myometrium and prevents contraction. What factors antagonize progesterone and trigger labor an delivery?
-distortion of myometrium -distortion of cervix -rising oxytocin levels lead to uterine contractions -rising estrogen levels increase sensitivity (ALL)
By the end of gestation, maternal blood volume normally increases by almost __ %
50
The extraembryonic membrane that forms a fluid filled sac is the
amnion
A space opens within the inner cell mass that will form the
amniotic cavity