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