Ch 10 - Conception & Fetal Dev Flashcards
Union between a single sperm and egg that marks the start of a pregnancy
conception
process of conception
gametogenesis
ovulation
fertilization
implantation
Process by which oocytes and spermatocytes are produced
Gametogenesis
When does oogenesis begin?
When does spermatogenesis begin?
oogenesis: during fetal life. When a female is born, she is born with all the eggs she will ever have (2 million, most of which degenerate, leaving only 400-500)
spermatogenesis: starting from puberty, continues into 80s and 90s.
Describe Ovulation
- what occurs
- hormones responsible for follicular rupture
- what occurs to make fraternal twins possible
Each month one ova matures and is released from its ruptured ovarian follicle
hormones responsible: LH, FSH. Occasionally, two ovum
are released, making fraternal twins possible
High levels of ________ increase the motility of the fallopian tubes so that the cilia are able to move the ova through the tube toward the uterus
estrogen
Most common site of conception
ampulla
If fertilization is to occur, it usually takes place in the _______ _______ of the tube
outer third
Ova are fertile for __ hours after ovulation. If fertilization does not take place in this timeframe, the ova breaks down and is reabsorbed.
24
Protective layers will need to be penetrated by sperm in order for fertilization to occur. This is able to occur when __________ from the ______ are released and aid in breaking down that protective coating of the ova
enzymes, sperm
Typical male ejaculation contains # - # million sperm & can live in a woman’s reproductive tract for # - # days
2-5 million sperm
2-3 days
Occurs when a sperm is able to penetrate the membrane surrounding the ova
At this time, both ova and sperm become enclosed in the membrane
fertilization
Progression of zygote to implantation
zygote –> 2 cell –> 4 cell –> morula (little mulberry) –> blastycyst/trophoblast/embryoblast –> implantation
eventually will be placenta
embryoblast
blastocyte
trophoblast
trophoblast
eventually will become embryo
embryoblast
blastocyte
trophoblast
embryoblast
whole structure of developing embryo
blastocyte
When the protective coating degenerates, trophoblast cells will displace the endometrial cells at the implantation site and the blastocyst embeds itself on the endometrium when uterus is at its most nourished
usually occurs in fundus endometrium w/in 6-10 days after conception
implantation
implantation in cervix
blocks baby’s passage
requires c-section
placenta previa
What will secrete enzymes to allow the fertilized egg to burrow into the endometrium and cover the blastocyst?
trophoblast
What occurs @ the site of implantation that makes implantation bleeding occur? - usually around the same time as the when a period might occur which makes women miss the first month of pregnancy
Endometrial blood vessels erode
conception - day 14
pre-embryonic
week 2 - 8
embryonic
Week 9 - birth
fetal
which period is the baby at greatest risk due to drugs, alcohol, trauma, malnutrition, smoking, lack of folic acid, measles?
what might these things cause?
Why is she @ greatest risk?
embryonic
spontaneous miscarriage or fetal development issues
mom doesn’t know she’s pregnant
When do people generally realize they’re pregnant?
6 weeks
What is the primary reason for barrier methods with pregnant women?
protection from STI
Develops into epidermis, glands, hair and nails, nervous systems, lens of the eye, tooth enamel, and floor of amniotic cavity
Ectoderm
Develops into bones, teeth, muscles, dermis, connective tissue, spleen, genitourinary, and cardiovascular system
Mesoderm
Lining of respiratory and digestive tracts, and the glandular cells of associated organs. Forms the roof of yolk sac.
Endoderm
which stage is most crucial for development and organogensis in babies?
rapid cell division occurs and most vulnerable to outside influences
By end of this stage, all organ systems are present, as well as external structures
Unmistakable human appearance by the end of this period - hands, feet, cardiac movement
embryonic
Covering of the FETAL side of the placenta. Contains the major umbilical blood vessels, attached to inside of uterus
chorion
Forms a fluid filled sac around developing embryo and covers the umbilical cord. Also covers the chorion on the fetal side of the placenta. Will enlarge with pregnancy to accommodate growing fetus
amniotic sac
greatest risk if amniotic sac is ruptured early?
chorioamnionitis
Why do you test amniotic fluid?
for genetics or see if lungs are matured → esp if you are induced at week 39
made up of fluid secreted by the respiratory and GI tract of the fetus, as well as sterile fetal urine beginning in week 11
what is the normal volume at term?
amniotic fluid
700-1000 ml
Functions of amniotic fluid
- temp
- F&E
- fetal movement
- cushion from trauma
- barrier to infection
- fetal lung dev
- prevent sticking
- fetal growth
- cushion for umbilical cord
- genetic studies/studies of lung maturity
Begins as connecting stalk that attaches amniotic sac and yolk sac to chorionic villi
Eventually will develop in stalk that supply nutrients and oxygen to embryo
Stalk gets compressed on both sides by amnion and results in …..
umbilical cord
# artery(ies) # vein(s)
2 arteries from embryo to placenta (w/ deoxygenated blood)
1 vein from placenta to embryo (w/ oxygenated blood)
What nasty thing is a protective covering over the umbilical cord?
wharton’s jelly
what 2 things result in decreased oxygenation and may contribute to fetal death?
compression
knotting
Serves two main functions-
- Nutrition/oxygenation
- hormone maintenance
placenta
takes over for corpus luteum to provide hCG, estrogen, progesterone, hCS
provides O2 & nutrients from mom to baby.
what happens if corpus luteum stops before placenta takes over?
miscarriage
What diseases cause problems w/ perfusion/nutrition transfer?
DM CV HTN Lupus obesity
What non disease might contribute to vasoconstriction btw placenta & baby?
coke smoking caffiene EtOH soft cheese smoked meat
What will result in diminished or absent blood flow to placenta and fetus?
hyperstimulation of uterus in labor
uterine rupture
3 shunts in fetal life
ductus venosus (umbilical vein to IVC) foramen ovale (R to L shunt) ductus arteriosus (pulmonary vein to aorta)
which shunt is related to the bypass of the lungs?
ductus arteriosus
what happens to blood in the fetal circulatory system?
- oxygenated blood goes from placenta to baby through umbilical vein.
- vein branches at liver and goes up IVC through ductus venosus
- goes to RA
- Passes to LA through foramen ovale
- goes to LV and into aorta via ductus arteriosus, which then goes to head/neck
- deoxygenated blood from head/neck return to RA via SVC
- Blood goes to RV, where it goes to pulmonary artery
- lung tissue resistant, most blood goes through ductus arteriosus
- goes through abdominal aorta and umbilical arteries where it goes back to the placenta.
- blood cleaned & returns to baby
How soon do shunts close after birth?
1st hr of life
When is the formation of blood?
3rd week
When does hematopoiesis occur?
6th week
When does a mom need RhoGAM?
28 weeks and right after birth
What blood Rh does the mom have to be to need RhoGAM?
negative
How much does blood increase by during pregnancy? Why?
1.5 L
To prepare for blood loss @ end of pregnancy
forms the primitive gut during embryonic stage
yolk sac
produces the pharynx, lower respiratory tract, esophagus, stomach, first half of duodenum, liver pancreas, and gallbladder. Most common problems are atresia and stenosis
foregut
becomes distal half of duodenum, the jejunum and the ileum, the cecum and the appendix and the proximal half of the colon. Common malformations are omphalocele and Meckel’s diverticulum.
midgut
develops into distal half of colon, rectum, anus, bladder, and urethra.
hindgut
what takes care of elimination & nutrition in a fetus?
placenta
what is fetal waste product that accumulates in the intestine?
meconium
what can cause meconium to be passed in utero?
stress
what might nonpassage post birth be indicative of?
perforation
ileus
atresia (closed/absent)
when is the GI tract mature?
36 weeks
what might cause a disconnect between what comes in and what goes out?
fluid imbalance.
DRINK GALLONS OF WATER!
what might you suspect w/ 1 artery & 2 veins?
kidney issues - can determine w/ US in utero
what do you do if baby has polycystic kidneys?
nothing. follow up w/ urologist.
what can you do if newborn has no kidneys?
nothing. May have to counsel mom to terminate b/c baby cannot get a transplant or dialysis
greater chance of meconium in amniotic fluid in later/earlier gestation?
later
how do you take a temp on a newborn?
axillary until baby has passed stool. do no want to perforate rectum.
when does glycogen start to store in fetal liver?
9-10 wks
how many times more stores does a baby have at term vs an adult?
why?
At term, has twice the stores of an adult
Helps compensate for stress of labor and delivery and loss of maternal glucose supply
how long can fetal stores of iron last if mom has inadequate intake?
5 months.
What can you encourage a mom to eat if she’s low on iron?
red meat, green leafy veggies. stay on prenatal vitamins.
what conjugates bilirubin for fetus? what will happen w/ hyperbilirubinemia?
placenta.
jaundice.
Why do you give vitamin K injections to babies?
When does vitamin K synthesis occur in babies?
clotting factors. not born w/ them. kicks in 6 weeks after birth when feeding pattern is established.
Resp:
If baby is born at 24 weeks, what will need to occur?
intubation until more alveolar form
At what week does a baby have enough surfactant to have the best chance of survival?
32 weeks
What L/S ratio in amniotic fluid indicates a baby’s lungs are mature?
2:1
What is given to babies born early to decrease RDS?
surfactant tx
Where does amniotic fluid in the lungs go when baby is in labor?
drains into amniotic fluid or swallowed by fetus.
What action by mom helps squeeze remaining fluid in lungs?
pushing for delivery.
less respiratory issues for vag births.
that’s why C-section babies are generally more mucousy.
too little amniotic fluid surrounding your baby in the womb
Oligohydramnios
what is oligohydramnios indicative of?
kidney dysfnc or absence of kidneys.
Newborn w/ low GFR and lack ability to concentrate urine poses risk for what complication?
over or underhydration
How many dirty diapers in 1 day indicates good hydration?
6-8
How many times should baby void in first 24 hrs?
at least once.
How else can you measure hydration in baby?
MM, skin turgor, fontanelles
At what week can movement be detected?
At what week can mom detect the movemenT?
11-12
16-20 (or earlier if after 1st baby)
What can result in neurological deficits?
hypoxia insult during labor - chronic HTN - smoking - drugs - toxoplasmosis - lead - oxygenation - maternal seizures - birth trauma - biggest reason for lawsuits - forceps - heart defects undetected - cerebral palsy
Endocrine:
What can cause retardation if not treated?
lack of thyroxine
What can lead to macrosomnia, immature lung fnc when untreated in mom?
diabetes
also hypoglycemia post delivery.
What interventions for newborn hypoglycemia?
What can happen if not treated during pregnancy?
macrosomia, neurologic defects
blood sugar w/in 30 min of delivery
if glucose is <30, put baby to breast or supplement ASAP
Reproductive
At what week is baby fully differentiated?
12 week. May detect w/ maternal blood tests.
US at 16 weeks.
Baby girl is showing bloody vag discharge and/or breast discharge. Baby boy has a GIGANTIC SCROTUM.
what is this caused by?
maternal hormones.
Defects in fusion or spinal bones (vertebrae) may result in what complication?
spina bifuda
if higher on spinal cord, paralysis of all extremities
if lower, lower extremity paralysis
Why are skull bones not completely ossified at birth?
allows for molding of bones to fit through birth canal. Connective tissue where bones meet are called fontanels
If bones are broken, suspect abuse.
thick, white substance that protects the skin. Copious at around 24 weeks but decreases to almost none at term
vernix caseosa
What week does subq fat appear?
32 weeks
a fine hair, starts to appear over eyebrows and lip at 12 weeks. By 20 weeks, covers body. Starts to disappear close to term
lanugo
what week are nails completely formed?
32-36 weeks
