Genetics part 2 Flashcards
What is mitosis?
Growth and replacement of body cells
What is meiosis?
Gamete cell production
How long does it take sperm to find the egg?
5 minutes to 6 hours
What is capacitation?
process that prepares sperm for fertilization…
- removes protective coating on sperms head
- sperm release hyaluronidase to break down zone pellucida on the ovum
- ovum moved through uterine tube by cilia
- sperm and ovum meet in the outer this of the uterine tub
- one 1 sperm gets thru, zone reaction blocks out the others.
When is the Pre-embryonic stage?
Conception through day 14
How long is the egg an embryo?
day 1 - week 8
How long is the thing a fetus ?
week 9 - birth
How long is gestation?
10 lunar months
9 calendar months
40 weeks from conception
280 days
How many chromosomes does each gamete have?
23 and when fertilized 46.
On day 2 what is it?
A zygote
What happens on day 3 ?
- first undifferentiated cell mass
- travels through the uterine tube.
all cells start dividing but they don’t have a job yet (undifferentiated)
What happens on day 4 and what is it?
Blastocyst
day 4
morula starts to differentiate…starts to figure out it’s job.
What are layers of the blastocyst on day 4?
Two layers:
Inner: Fetus and amnion
Outer: Trophoblast (chorion and placenta)
What happens on day 8-10?
Blastocyst imbeds in endometrium, usually in fundus
Mom may experience implantation bleeding(spotting that can be confused with period)
What and where is decidua basalis?
directly under the embryo and it’s the thickened endometrium?
What is the decidua
capsularis?
encapsulatesthe trophoblast(outer layer of developing embryo)
What is the decidua vera?
remainder of the uterine lining.
What is the chorionic villi?
Finger-like projections from trophoblast
Link to maternal blood supply
Excrete waste until the placenta takes over
what are the 3 layers of cells aka “germ layers”
-Ectoderm
-Mesoderm
-Endoderm (stems in yolk sac-early
GI system)
it is the most critical period for development.
What are the membranes?
Chorion
Amnion/amniotic cavity
when does the fetus start contributing for amniotic fluid?
11 weeks
What does the umbilical cord do? tell me about it
Supplies embryo and fetus with maternal nutrients and oxygen-rich blood
Forms from connecting stalk
2 arteries, 1 vein (AVA) and Wharton’s jelly for cushioning and helps blood not get compressed.
What does the placenta do? tell me about it
Involved in fetal circulation by day 17
Functions as endocrine gland, metabolic function and waste, and nutrient storage
Certain pathogens and drugs can pass through
Does estrogen speed or slow things up?
Estrogen: speeds things up, n/v, breast tenderness
