ch. 12: conception and fetal development Flashcards
How long does pregnancy last?
40 weeks
What are the three stages of intrauterine development?
1) pre-embryonic
2) embryonic
3) fetal
The embryo stage lasts from ___ to ___
day 15 to week 8
What stage is the most critical time in development of the organ systems and the main external features?
embryonic stage
What is the embryo especially vulnerable to during the embryonic stage?
malformations caused by environmental teratogens (smoking, drinking, drugs)
What are the functions of the amniotic fluid?
1) allows freedom of movement and symmetrical growth
2) warm and helps fetus maintain constant body temp
3) cushions against shock
4) barrier against infection
5) source of oral fluid & repository for waste
6) maintenance of fluid & electrolyte balance
7) factor in assessing fetal well being
What is OLIGOHYDRAMNIOS?
- too little amniotic fluid < 300 ml
- indicates renal abnormalities
What is POLYHYDRAMNIOS?
- too much amniotic fluid > 2,000 ml
- indicated GI abnormalities
How many arteries does the umbilical cord have?
2
How many veins does the umbilical ord have?
1
What structure carries OXYGENATED blood to the fetus?
the umbilical vein
What structure carries DEOXYGENATED blood away from the fetus?
the 2 umbilical arteries
What is Wharton’s Jelly?
connective tissue that surrounds the vessels of the umbilical cord and prevents compression of the blood vessels to ensure continued nourishment of embryo
What is nuchal cord?
when the cord is wrapped around the fetal neck
What are the metabolic functions of the placenta?
1) respiration: functions as lungs for the fetus
2) nutrition
3) excretion
4) storage
the placenta prevents the ___ of the mother and embryo from mixing
blood
What effect does low blood pressure have on the circulation to the fetus?
low BP= low blood circulation to fetus
What is supine hypotension?
When the woman lies on her back, the pressure of the uterus compresses the vena cava and blood return to r. atrium is diminished
What position is optimal for circulation
lying on the side
What determines the lung maturity of the fetus?
Lecithin & sphingomyelin (L/S ratio)
What L/S ratio indicates that the fetal lungs are mature?
2:1
What are the 3 temporary pathways that bypass the fetal lungs and liver to facilitate oxygenation?
1) ductus areteriosius
2) foramen ovale
3) ductus venosus
Where is the DUCTUS ARTERIOSIUS?
between the pulmonary artery and descending aorta
Where is the foramen ovale?
temporary opening between the left atria and right atria
