Conception & Prenatal Development Flashcards
What’s the name of cell division needed for gametogenesis?
Meiosis
Each gamete receives how many autosomes and sex chromosomes?
22 autosomes and 1 sex chromosome
__ total chromosomes in new cell when gametes come together
46
Name of formation of ova
Oogenesis
By what week of gestation will the female fetus have all the ova?
30th week
Man or woman determines baby’s sex?
Man gives either X or Y
The ovum has the capacity to be fertilized no longer than __ hours after ovulation.
24 hours
How long can sperm survive?
1-2 days
How long can sperm remain in female tract?
80 hours
What happens during the pre-embryonic period?
The zygote enters the uterus and implants in the decidua. 2 weeks after conception.
What happens during the embryonic period?
From 3rd week until 8th week. By the end of 8th week, all major organ systems are in place. Teratogens can cause structural damage.
What are the three layers of the embryonic disc?
Ectoderm, mesoderm, endoderm
When is the fetal period?
9 weeks after gestation. Is now a fetus. Dramatic growth period.
What are the major functions of the placenta?
Metabolic, respiratory, and endocrine.
Where is the placenta inserted?
Fetal side near center.
How heavy is the placenta?
1/6 weight of fetus at birth
What are the 2 fetal membranes?
Amnion (inner)
Chorion (outer)
What is the purpose of the amniotic fluid?
It cushions the fetus and allows for normal prenatal development. It also maintains stable temperature.
How many arteries and veins does the umbilical cord have?
Two arteries and one vein.
Describe the course of fetal circulation.
Umbilical arteries carry de-O2 blood from fetal heart to placenta, exchanges oxygen and waste products, back to fetus thru umbilical veins for delivery to fetal tissues
Name the three fetal circulatory shunts that bypass fetal liver and lungs.
Ductus venosus, foramen ovale, and ductus arteriosus
How long does it take for a zygote to implant in the decidua?
6-10 days. Needs constant estrogen & progesterone to survive.
Where in the uterus does the zygote implant?
Upper uterus because it is richly supplied with blood and is thicker.
What does the chorion do?
Surrounds the amnion
What does the amnion do?
Protects the developing embryo
