week 9 through 12
head 1/2 total length of the fetus; contents enter the abdomen;fetus begins producing urine and excretes it into the amniotic fluid; fetal gender can be determined by the end of this period.
week 13 through 16
quickening is felt, normally by women who have been pregnan before. fetus grows rapidly in length; face looks human, eyes and ears positioned.
weeks 17 through 20
changes in hair and skin; Vernix caseosa fatty cheese like substance secreted by fetus sebaceous gland;lanugo-fine hair covers the body;brown fat;heat producing fat is on the back of the neck,behind the sternum and around the kidneys(maintains temp) vernix diminishes around 38-39 weeks
weeks 21 through 24
minimal sub q fat; skin translucent and red;lungs produce surfactant, reduces surface tension and prevents collapsing.; capillary network still immature; fetus less likely to survive if delivered here.
weeks 25 through 28
fetus more likely to survive as maturation of lungs, cns, pulmonary; blood formation shifts from spleen to bone marrow, eyes reopen; usually assume a head down position; better likely hood to survive
weeks 29 through 32
skin is pigmented to race, toenails and finger nails present fetus has more sub q fat, good chance of survival at this gesstation; 29 weeks may need ventilator
weeks 33 through 38
growth continues but slows as the fetus reaches full term; primarily gainging weight; pulmonary system matures; large amt of sub q fat; vernix and lanugo diminish, testes decend(maturation of all systems)
Auxillary structures; placenta side 1
maternal side attaches towards the fundus; EXCHANGE OF SUBSTANCES OCCURS WITHIN THE INTERVILLOUS SPACE; transports O2 and nutrients and rids of waste-fetal heart cirulates the blood.
Auxillary structures;placenta side 2
Fetal side; blood is transported from the fetus to the fetal side of the placenta by two umbilical arteries and one vein blood is circulated to and from the fetal side of the placenta by the fetal heart.
The Placenta produces
glycogen, cholesterol, fatty acids; exchanges O2 and CO2, rids of waste and exchanges nutrients
Placental hormones and IgG
hormones; Estrogen, Progesterone ( hormone of pregnancy) HPL- human placental lactagon; IgG provides passive immunity against disease.
Fetal membranes and amniotic fluid
fluid-protects umbilical cord; amnion and chorion-so close they look like one layer.Amniotic fluid cushions, maintains temp, sysemic development protects fetal parts, room and buoyancy; need adequate fluid for baby lung support
less than 50% expected ; 10-12 pockets normal fluid lower must have more than 1 ultrasound to diagnose
excesssive fluid, may exceed 2000ml; can cause rupture which detaches placenta causes harm to cord.
2 arteries carry away deoxygenated blood and waste away from fetus; 1 vein carry oxygenated and nutrient rich blood to the fetus
first shunt; about half the blood goes through the liver and the rest bypasses the liver and enters the inferior vena cava thought this shunt
second shunt; most of the blood passes directly into the left atrium through this shunt
third shunt; the rest of the blood from the right ventricle joins oxygenated blood in the aorta through this shunt.