chapter 16 and 17 text Flashcards
after the nucleus of a sperm and the nucleus of an egg fuse, fertilization is complete, and the new, diploid cell is referred to as a
Zygote
The zygote travels down the fallopian tube, heading for the uterus so it can implant in the
Uterine lining
As the zygote travels it undergoes what
Cleavage
What is cleavage
A rapid series of mitotic divisions that result in a multicellular embryo
The zygote divides into 2 cells, then 4 cells, then 8 cells, then 16 cells which at that point the zygote is a solid ball of cells called a
Morula
Cell division continues, but the morula becomes filled with liquid, which pushes the increasing number of cells out toward the periphery of the embryos membrane, forming a hollow ball of cells called a
Blastula
When does the blastula become a blastocyst
A group of cells inside the blastula become specialized to form the embryo & the blastula becomes a blastocyst
The flattened cells along the edge of the blastocyst from the
Trophoblast
The fluid-filled cavity is called the
Blastocoel
The sphere of larger, rounded cells thats destined to become the embryo is called the
Embryoblast
If the blastocyst doesn’t implant in the wall of the uterus, there is no what
Pregnancy
If conception occurs, the trophoblast cells of the blastocyst go on to form the
Chorion, which becomes part of the placenta
After implanting itself, the developing mass of cells moves inward, forming a ball of cells called a
Gastrula that has 3 layers
This is the outer layer of the gastrula, it develops into the skin and nervous systems
Ectoderm
The middle layer of the gastrula develops into the muscular, skeletal and circulatory systems
Mesoderm
The innermost later of the gastrula gives rise to the linings of your digestive and respiratory tracts, as well as organs such as the liver and pancreas
Endoderm
An egg can be fertilized, but a woman isn’t pregnant until the blastocyst is what
Rooted in her uterine wall where it can develop further
Every organ in your body forms during the
Embryonic period-the 1st trimester of pregnancy
After gastrulation, the specialized cells of the ectoderm, mesoderm, and endoderm begin migrating toward other cells with the same specialty, this cellular migration is referred to as
Morphogenesis, because it gives the embryo a shape
Outside the embryo what develops
Specialized membranes
The chorion combines with tissues created by the mother to become the
Placenta
An organ thats filled with blood vessels and provides a large surface area for the exchange of gases, nutrients, and wastes
Placenta
What protects the developing embryo
The amnion surrounds the amniotic cavity, which fills with amniotic fluid
The fetal period encompasses the last
6 Months of pregnancy, or the 2nd and 3rd trimesters
