pregnancy and embryonic development

path of prenatal development

fertilization of an egg cell; implantation of the zygote in the uterus; multiple cell divisions to initiate growth and directionality of the embryo; development of the embryo into the fetus; maturation of the organ systems in the fetal body; to the point of birth

prenatal

prior to birth

gestation

describes the period of prenatal development

about 40 weeks/9 months

how many weeks/months is the period of gestation

there is 3 trimester and each trimester is 3 months

how many trimesters are there and what is the duration of each trimester

first trimester

major germ layers are created and the internal scaffolding of the embryo is created. germ layers give rise to all the major tissues of the body (cardiovascular structures; skin; nervous tissue; etc.) Basically, the embryo starts forming its basic layers, like building blocks. These layers later turn into all the important parts of the body — like the heart and blood vessels, skin, brain, and nerves.

second trimester

further development of organs and organ systems; embryo starts to look like a human

Third trimester

significant growth of the body and its systems. These organs actually starting to become functional

first trimester

This is the time when the embryo is the most fragile/vulnerable and likely to be lost. Only about 40% of pregnancies make it through this stage.

gastrulation

key step that occurs through the first trimester

gastrulation

involves a series of steps to create the major germ layers. These germ layers creates the major tissues and organs of the body

gastrulation

directionality of the embryonic body is established here

endoderm, mesoderm, ectoderm

what are the 3 germ layers that are created during gastrulation

True

each germ layer creates specific tissues and organs of the body. True or False

develops during the first trimester

placenta

paired umbilical arteries meaning 2; singular umbilical vein

blood flows from the fetus to the placenta in the…..; returns back to the fetus through a ……..

umbilical cord

physically connects the embryonic/fetal body with the placenta and contains multiple blood vessels

placenta

is physically adjacent to the uterine wall in the mother’s body

there are two umbilical arteries and one umbilical vein

what is inside the umbilical cord

singular umbilical vein

carries the oxygen and nutrient rich blood away from the mother/placenta and carries that blood into the fetus

paired umbilical arteries (2)

carries the poor oxygenated waste blood out of the fetus and brings the blood toward the placenta/mother so that it can be replenished with oxygen and nutrients

from the umbilicus (belly button)

where does the umbilical blood vessels enter and exit from

since it is in a liquid environment, the fetus does not need the lungs and liver to breathe. the fetus uses the placenta for oxygen, so blood takes shortcuts around the lungs and liver. After birth, these bypasses will close so blood can flow to the lungs and liver.

Why does fetal blood bypass the lungs and liver, and what happens after birth?

amnion

layer holds amniotic fluid surrounding the fetus.

it means the amnion has torn allowing the amniotic fluid to escape

what does it mean for when a woman in labor say her water breaks

mucus plug

serves to prevent entry of bacteria into the uterus. It is at the base of the uterus

organogenesis

the process of organ formation during the first trimester is known as ….

organ maturation

takes place during the second and third trimester.

formed; maturating

by birth, most of the organs have been ______ but are still _______.

lungs

what tends to be the last organs to mature for a fetus

uterus will increase from 7.5cm to 30cm, contain almost

5 L of fluid, uterus and contents will weigh about 22 pounds, maternal abdominal organs are pushed out of the normal positions to make space for the baby but they still remain functional; just displaced; ultimately pushed upwards because of the expansion of the uterus

what are some of the changes during prenatal development/gestation

urinary bladder

what is pushed all the way down by the expanded uterus in a mother’s body

because the urinary bladder is pushed all the way down to the expanded uterus

this is why pregnant woman always feel the urge to pee

parturition

technical term for labor

labor/parturition

involves a series of strong, rhythmic contractions of the uterine wall

to push the baby out/expulsion of baby

what is the goal of labor

dilation, expulsion, and placental stages

what are the 3 stages of labor

oxytocin

what hormone stimulates contraction of the uterus

dilation stage

The cervix dilates, the fetus is pushed by muscular contractions into the cervical canal, and the amnion ruptures – water breaking

expulsion stage

•The movement of the fetus through the cervical canal and vagina

•Delivery can be helped by episiotomy or cesarian section

placental stage

Ejection of the placenta (afterbirth)

the amnion tears in the dilation stage, the fetus emerges during the expulsion stage, and the placenta emerges during the placental stage

can you explain the stages of labor simply

premature labor

refers to labor that begins prior to full development being reached. Fetuses who are typically born before 36/37 weeks. These babies will survive as long as they receive adequate medical care

24

fetuses born before ______ weeks will usually not survive because the organ systems have not developed enough to sustain life outside the womb.

neonatal period

first month after birth

what happens to the baby during neonatal period

lungs will fill with air, breathing commences, the heart bypasses should slowly begin to shut, heart rate should drop to about 80-130 beats per minute, digestive organs start working, kidneys become active and start filtering blood, metabolism increases to sustain adequate warmth for the newborn

superior surface

The adrenal glands are found on which surface of the kidney (medial; superior; posterior; etc)?

from implantation to the end of the eight week of gestation

Embryonic development occurs during this period.

from implantation to the end of the eighth week of gestation

from the ninth week of gestation to birth

from conception to birth

from fertilization to implantation

C

4. What is the correct order of early development stages?

A) Fertilization → Embryo → Zygote → Fetus
B) Zygote → Fetus → Embryo
C) Fertilization → Zygote → Embryo → Fetus
D) Implantation → Zygote → Fetus → Embryo

form the endoderm, mesoderm, and ectoderm that will become specific tissues and organs

Part of the gastrulation phase includes the formation of germ layers that will...

D

The umbilical arteries do the following:

A - move blood from the fetal heart to the fetal lungs

B - move blood from the fetal lungs to the fetal heart

C - bring oxygenated blood and nutrients toward the embryo/fetus.

D - take deoxygenated blood and waste away from the embryo/fetus

10 cm

The cervix is fully dilated and ready for expulsion of the fetus at ...