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46 Cards in this Set

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cleavage
early embrionic divisions; cleavage always results in an increasing ratio of nuclear to cytoplasmic mat and increases the surface-to-volume ratio of each cell as well
indeterminate cleavage results in cells....
that are still totipotent- can develop into a complete organism
a determinate cleavage results...
in cells with specified differentiation pathways
The zygote divides into __ cells in approx ___ hrs; at which point it should be at the ______
8; 72; uterus
The first stage of the zygote; a solid ball of cells
morula
the morula develops a ______, beginning the process of _____
fluid-filled cavity aka blastocoel; blastuation
Blastocyst
mammalian blastula
Cell Groups of Blastocyst
Inner cell mass--> protrudes into the blastocoel
Trophoblast--> surrounds inner cell mass and blastocoel
When does implantation occur?
during blastulation
The hormone ____ prepares the uterus for implantation by....
progestorone; thickening the endometrium
Proteolytic enzymes
secreted by the embryonic cells in order to enable the embryo to plant into the uterine wall. Eventually allows for the exchange of resources from mom->baby
After implantation the blastula...
undergoes cell migration to become a three-layered GASTRULA... 2-layers arise from an invagination; 3 from further folding.
The fresh cavity of the gastrula?
The archenteron- this develops into the gut (alimentary canal)
Opening of the Archenteron?
Blastopore; In _DEUSTEROMES_ becomes anus. in PROTOSOMES becomes mouth
Three primary germ layers?
Ecto(outer)derm and Endoderm arise first followed by the Mesoderm.
WHICH DERM?
Lens of the eye
Ectoderm
WHICH DERM?
epithelial linings of dig/ resp tracts
Endoderm
WHICH DERM?
Epidermis
Ectoderm
WHICH DERM?
nails
Ectoderm
WHICH DERM?
bicep
Mesoderm
WHICH DERM?
bladder
Endoderm
WHICH DERM?
Brain stem
Ectoderm (NS)
WHICH DERM?
liver
Endoderm
pancreas, thyroid
WHICH DERM?
gonads
Mesoderm
Differentiation arises from
selective transcription of genomes
Induction, embryonically speaking is?
The influence of a specific group of cells on the differentiation of another. Mediated by chemical _inducers_
The rudimentary development of the NS
Neurulation
Neurulation begins with...
The development of a rod of mesodermal cells, NOTOCHORD, along the longitudinal axis of the fetus; just under the ectoderm
The notochord has an ___ effect;
expand
inductive; the overlying ectoderm bends inwards and grow upward till they fuse, forming a _NEURAL TUBE_ , which then goes on to disconnect from the surface ectoderm.
After the formation of the Neural tube from the ______...
ectoderm; the cells at the tip of what were the neural folds are termed the neural _crest_
The neural crest cells go to what end?
They migrate laterally to become the PNS, inc the sensory ganglia, autonomic gang, schwann cells, adrenal medulla...
After eight weeks of gestation the embryo..
is called a fetus
The two major components of the Fetal Respiratory System
Placenta and Umbilical Cord
Placenta Formation
Begins with the CHORION, surrounding membrane of AMNION (thin,tough, membrane w/ amniotic fluid (shock absorber)). Chorion extends chorionic villi into uterine wall.
Umbilical Cord Formation
The _ALLANTOIS_ develops as an outpocketing of the gut. The blood cells of the allantoic wall enlarge and become umbilical vessels; The Yolk Sac, site of early development of blood vessels, and Allantois, become enveloped by the placenta and form the embryonic cord.
Hb-F vs Hb-A
Fetal Hemoglobin has a much higher affinity for 02 than does adult Hemoglobin; EXCHANGE of nutrients occurs via diffusion in the placenta
So order the different cell stages of embryo:
zygote-->8-celled ball@72hr-->morula-->blastocyst-->gastrula
Fetal Circulation:
Blood oxygenated...
in the placenta NOT the lungs
Fetal Circulation:
There are three shunts whose sole purpose is to...
divert blood from the lungs
Fetal Circulation:
The ______ carries oxygenated blood from the placenta to the fetus
umbilical vein
Fetal Circulation:
The blood from the umbilical vein bypasses the liver...
by way of the _DUCTUS VENOSUS_; converging with the inferior venae cavae
Fetal Circulation:
The inf and sup venae cavae return deoxygenated blood...
to the right atrium. The blood in the R atrium is only partially oxygenated as it is a mix of the umb vein and deoxy blood.
Fetal Circulation:
From the R atrium,....
most blood bypasses pulmonary circulation, and goes directly from the R atrium to the L atrium via the _FORAMEN OVALE_
Fetal Circulation:
What is left in the R atrium...
empties into the R ventricle and is pumped into the pulmonary artery. Most blood is shunted from the artery to the aorta via the _DUCTUS ARTERIOSUS_
Fetal Circulation:
The pulmonary arteries carry...
partially oxygenated blood to the lungs
Fetal Circulation:
In a bebe, the pulmonary vein..
carries fully deoxygenated blood to the left atrium, This blood mixes witg tge partially oxyg blood from the right atrium (_Foramen OVALE), before being pumped into systemic circ by the left ventricle