Biological Beginnings Flashcards
What is the fertilized egg called?
Zygote
What genes determine a female zygote?
XX
What genes determine a male zygote?
XY
What are the first 14 days from conception called?
preembryonic development
What begins as the zygote moves through the fallopian tube toward the uterus?
cellular multiplication
How many days does cellular multiplication take?
3 days
What is the rapid mitotic division called that the zygote makes in the fallopian tubes?
cleavage
What are the cells called that develop during cleavage?
blastomeres
The blastomeres eventually form a solid ball of how many cells? what is this ball of cells now called?
12-16 cells
morula
As the morula enters the uterus the intracellular fluid increases and a central cavity forms within the cell mass. Inside this cavity is an inner solid mass of cells..what are these cells called?
blastocyst
What is the out layer of cells that surround the cavity in the morula called?
trophoblast
Where does the trophoblast attach itself for nourishment?
to the surface of the endometrium (inner layer of uterus)
Where is the most frequent site of attachment?
upper part of the posterior uterine wall
How many days after fertilization does it take before the blastocyst implants itself into uterine lining?
7-10 days
The lining of the uterus thickens below the implanted blastocyst, and the cells of the trophoblast grow down into the thickened lining, forming what processes?
chorionic villi
After implementation what is the endometrium called?
decidua
What is the portion of the decidua called that covers the blastocyst?
decidua capsularis
What is the portion of the decidua called that is directly under the implanted blastocyst?
decidua basalis
What is the portion of the decidua called that lines the rest of the uterine cavity?
decidua vera
What forms the fetal portion of the placenta?
chorionic villi that is in contact with the desidua basalis
What part of the desidua is the maternal part?
decidua basalis
What happens in the 10-14th day after conception?
blastocyst divides into 3 germ layers
What are the 3 germ layers called?
- ectoderm
- mesoderm
- endoderm
What will develop from these primary germ layers?
all tissues, organs and organ systems
What is ectoderm?
outer layer of cells in an embryo
What is the mesoderm? and what does it do?
germ layer between the ectoderm and endoderm
produces all connective tissue, muscular, skeletal, circulatory, lymphatic and urogenital systems and linings of the body cavities
What is the endoderm? and what does it do?
the innermost germ layer
produces epithelium of digestive tract and its associated glands, respiratory organs, bladder, vagina and urethra
At the same time as the germ layer is developing the embryonic membranes form what?
- chorion (first membrane)
- chorionic villi
- amnion (second membrane)
What does the chorion enclose?
the amnion, embryo and yolk sac
Where does the amnion membrane originate from?
the ectoderm
What is the function of the amnion?
protects baby from bouncing
temperature regulator
expands until it comes in contact with chorion
What does the amnion contain?
amniotic fluid
How many mls of fluid at 10 weeks vs. at birth?
10 weeks - 30mls fluid
birth - 1000mls fluid
What is the purpose of the yolk sac? how long does it last and where does it eventually go? what takes its place?
forms primitive red blood cells
lasts about 6 weeks then absorbed into cord
spleen takes its place once it is up and running