fetal G&D

conception steps

oocyte released from follicle

follicle becomes corpus luteum

oocyte fertilized in outer 1/3 of fallopian tube

fertilized egg called zygote

zygote begins cleavage

2 cells to four cells to morula by day three ish

morula keeps cleaving to become blastocyst

blastocyst is formed in uterus as cells kept traveling down the fallopian tube

blastocyst

after morula

two parts: embryoblast cells and trophoblast cells

embryoblast cells become embryo and trophoblast cells become placenta

embedded blastocyst will release hCG

trophoblast cell

part of blastocyst

cause implantation

bury into uterine lining

progesterone

released by corpus luteum

will thicken uterine lining to allow for blastocyst to implant

peaks 7 ish days after ovulation (around time blastocyst will be in uterus ready to implant)

hCG

Human chorionic gonadotropin

embedded blastocyst will release

will stimulate corpus luteum to stay active and keep releasing progesterone, maintains pregnancy until placenta takes over

what pregnancy tests look for

helps placenta grow

embryonic stage

day 15ish to 6 weeks

when everything is really forming

stage where fetus is most susceptible to teratogens bc period of organogenesis

germ layers

three layers - ectoderm, mesoderm, endoderm

ectoderm

outside layer

skin, nails, hair, eye and ears

nervous system, pituitary gland

mesoderm

bone and cartilage

skeletal muscles cardiac muscles, smooth muscles

kidneys adrenal cortex

bone marrow and blood, lymphatic tissue

endoderm

digestive system

liver, mucosa of gallbladder and esophagus

thyroid gland and pancreas

fetal stage

9 weeks to birth

maturation of organs

what system is developmentally complete by end of embryonic stage

cardiovascular system - first organ system to function

umbilical cord

develops from connecting stalk

contains whartons jelly which provides cushion for vessels inside cord

vessels in the umbilical cord

3 vessels - one vein and two arteries

vein carries oxygenated blood from placenta to fetus

arteries carry deoxygenated blood from fetus to placenta

nuchal cord

cord around neck

doesnt suffocate baby bc baby isnt breathing but can make birth challenging

placental development

come from trophoblast cells

placenta is made up of cotyledons

fetal portion of placenta is called chorion

hPL

human placental lactogen

released by placenta

helps with insulin and metabolism

slight insulin resistance

placenta allows for what exchange

antibodies (passive immunity), bacteria, meds

doesnt allow maternal and fetal blood to mix

fetal circulation

fetal lungs do not function for gas exchange

special fetal adaptations in fetal circulation

ductus venosus, foramen ovale, ductus arteriosus

fetal Hgb carries more O2

greater Hbg concentration

higher cardiac output than adult - heart beats much faster

ductus venosus

allows some blood from umbilical vein to bypass liver and go directly into inferior vena cava

foramen ovale

connects right and left atrium

ductus arteriosus

shunts blood from pulmonary artery to descending aorta

surfactant

keeps alveoli open, fatty lining in alveoli cells, can keep fatty makeup in amnotic fluid

can use it to tell if lungs are mature but invasive procedure

squeezed out during vaginal birth

lecithin to sphingomyelin ratio that indicates lungs ar mature

L/S ratio of 2:1

hepatic system during fetal development

storage of glycogen which is major energy source for fetus

vitamin k

lack of vit K synthesis means coagulation factors cannot be activated

prophylactic (preventative) administration of phytonadione

renal system

fully functional at birth

but low GFR so higher likelihood od dehydration or overhydration

urine excreted into amniotic fluid

amniotic fluid

fluctuates in amount bc fetus absorbs and pees it out again

functions as cushion and allows fetus to move to gain some muscle

keeps fetus consistant temperature

amniocentesis

collection of amniotic fluid

polyhydramnios

too much amniotic fluid

oligohydramnios

not enough amniotic fluid

pancreas in fetal development

islets of langerhans develop in first trimester

uncontrolled materal diabetes can lead to fetal macrosomia

IgG

crosses placenta

IgM

produced by fetus by end of first trimester

produced in response to blood group antigens

IgA

not produced by fetus

colostrum has large amounts

cant form while gut is sterile