Forming an embryo (exam 2) Flashcards
Placentation is the formation of…..
placenta
Placentation is complete by weeks 14-16. As a fully developed organ, (maternal and fetal tissue working together) the placenta provides….
-nutrition
-excretion of wastes and metabolites
-respiration/ventilation
-endocrine function (hormones)
The placenta connects to the conceptus via the umbilical cord that contains ___________________, which carries deoxygenated blood, CO2, and wastes from the fetus, and ___________________ through which nutrients and oxygen are carried from the mother to the fetus
2 umbilical arteries, a single umbilical vein
Note: This is opposite of most veins/arteries!!!!
How does transport across the placenta occur?
-simple diffusion (oxygen, CO2, and other lipid soluble substances
-facilitated diffusion (water soluble glucose)
-active transport (amino acids and iron)
T/F: Maternal and fetal blood do not mix because blood cells cannot move across the placenta
TRUE
Maternal and fetal blood do not mix because blood cells cannot move across the placenta. RBCs are not exchanged, but the ____________________ provide ample SA for the 2-way exchange of substances between maternal and fetal blood
chorionic villi (theres a chorion before the placenta)
The fetal component of the placenta is derived from the _________________ and ____________________________, the maternal component is derived from the ________________________________
trophoblast, extraembryonic mesoderm, uterine endometrium
(by the beginning of the 2nd month, the trophoblast is characterized by a great number of secondary and tertiary villi, which give it a radial appearance)
As the blastocyst implants, it stimulates a response in the uterine endometrium called the….
decidual reaction
The cells of the endometrial stroma accumulate lipids and glycogen and these cells are called….
decidual cells
The endometrial stroma thickens and becomes more highly vascularized. This is called….
decidua
The protruding portion of the embryo (closest to the uterine cavity) is covered by a thin capsule of endometrium called the ___________________. The embedded embryonic pole of the embryo is underlain by a zone of decidua called the ________________, which will participate in forming the mature placenta (maternal side). The remaining area is called the ________________
decidua capularis, decidua basalis, decidua parietalis
As the fetus grows, the decidua capularis is pressed against the decidua parietalis, and in the 5th/6th months, the decidua capularis disintegrates. By this time, the placenta is _______________ and has distinct fetal and maternal surfaces
fully formed
Mesoderm cells travels through the primitive streak and forms the cardiogenic area or primary heart field which then forms 2 tubes under the influence of ________ from endoderm. At the inferior end, each endocardial tube is connected to vitelline veins
VEGF (vascular endothelial growth factor)
What happens during lateral folding for cardiovascular development?
1) 2 endocardial tubes fuse and forms primitive heart tube
2) viteline veins fuse and forms the sinus venous (inflow tract for vein to go into the heart)
3) aortae fuse and forms aortic sac (outflow tract)
4) primitive pericardial cavities fuse around the heart tube amd forms the pericardial cavity
2 endocardial tubes fuse and forms the…..
primitive heart tube
Viteline veins fuse and forms the…
sinus venous (inflow tract of vein into heart)
Aortae fuse and forms the….
aortic sac (outflow tract)
Primitive pericardial cavities fuse around the heart tube and forms the….
pericardial cavity
What happens during craniocaudal folding?
primitive heart is pushed towards the chest and the heart tube reaches the thorax
The heart tube elongates, swells, and forms 5 dilations, from caudal to cranial:
EXAM Q
1) sinus venous (caudal end, this is a major way into heart)
2) atrium
3) ventricle
4) bulbus cordis
5) truncus arteriosus (cranial end)
note: most things form cranially to caudally but the heart tube is opposite!
The sinus venosus develops into….
R/L sinus horns that bring in blood