Embryogenesis and Development Flashcards
Fertilization
secondary oocyte travels to fallopian tube where it can bind to sperm; now is a diploid zygote
Cleavage
after fertilization, zygote implants in uterus; undergoes rapid mitotic divisions; officially becomes an embryo; overall size doesn’t change-divides into progressively smaller cells that will later be able to differentiate into different cell types
Blastulation
solid morula forms blastula, hollow ball of cells with fluid inner cavity
morula
embryo becomes solid mass of cells after multiple divisions
chorion
trophoblast cells of the blastula give rise to chorion which develops into the placenta
umbilical cord
connects the embryo to placenta; has arteries that carry deoxygenated blood and waste to placenta for exchange
gastrulation
generation of three distinct cell layers: ectoderm, mesoderm, endoderm
Ectoderm
gives rise to epidermis, hair, nails, nose, mouth, anal canal, eye, nervous system, inner ear
mesoderm
gives rise to musculoskeletal, circulatory, and excretory systems, gonads, muscular and connective tissues
endoderm
digestive and respiratory tracts, including the lungs; pancreas, thyroid, bladder, urinary tract
selective transcription
allows cells with same genes to develop into different cell types by only turning on the genes required to fulfill the specific function
neurulation
development of nervous system, derived from ectoderm; neural folds on surface of ectoderm fuse into neural tube, which gives rise to cells of central nervous system
Teratogens
substances that interfere with development of the embryo; includes alcohol, drugs, viruses, bacteria, environmental chemicals
determination
commitment of a cell to have a particular function in the future; after determination, cell is committed to specific lineage, but hasnt yet performed its function
differentiation
after cell’s fate has been determined, cells changes structure, function, and biochemistry in order to develop into that particular cell type
Inducers
cell that secretes a signal intended for another cell; often are growth factors which promote differentiation and mitosis
placenta
organ where nutrient, gas, and waste exchange occurs, mostly through diffusion; placental barrier provides immune protection ; oxygenation occurs in placenta, not lungs!
fetal hemoglobin
has greater affinity for oxygen compared to adult hemoglobin; helps with the retention of oxygen in fetal circulation
umbilical arteries
carry blood away from fetus towards the placenta
umbilical veins
carries blood towards the fetus from the placenta
2 shunts that reroute blood from fetal lungs
foramen ovale: one-way valve that connects right atrium to left atrium, so blood flows into left atrium instead of right ventricle and out through aorta; ductus arteriosus: shunts blood from pulmonary artery to aorta
shunt that keeps blood from fetal liver
ductus venosus: shunts blood returning from placenta directly to inferior vena cava
First trimester
major organs begin to develop, heart begins to beat, skeleton begins to harden, brain becomes fairly developed, embryo becomes known as a fetus
Second trimester
fetus undergoes a lot of growth, begins to move within amniotic fluid, face becomes more developed
Third trimester
rapid growth and brain development, antibodies transferred from mother to fetus for later protection; growth slows as fetus has less room to move around
Birth
vaginal childbirth accomplished through contractions of uterine smooth muscle, coordinated by prostaglandins and oxytocin; first amniotic sac ruptures, then strong contractions and birth of fetus, last- expulsion of placenta, umbilical cord
