BIO Ch. 3 Embryogenesis & Development Flashcards
What is the pathway of sperm penetrating an egg?
The sperm uses the acrosomal enzymes to penetrate the corona radiata and zona pellucida, causing a release of calcium ions, which prevents additional sperm from fertilizing the egg and increasing the metabolic rate of the resulting diploid zygote. Once it contacts the oocyte’s plasma membrane, the sperm establishes the acrosomal apparatus and injects its pronucleus.
Where does fertilization occur?
in the ampulla of the fallopian tube
What is the diff b/w di and monozygotic twins?
fraternal (dizygotic) twins results from the fertilization of 2 eggs by 2 different sperm, while identical (monozygotic) results from the slitting of a zygote into 2
When does a zygote become an embryo?
after the first cleavage (divisions of embryonic cells) because it is no longer unicellular
What is the diff b/w indeterminate and determinate cleavage?
indeterminate cleavage results in ells that are capable of becoming any cell in the organism, while determinate results in cells that are committed to differentiating into specific cell types
What are the 2 different cell types of the blastula?
blastocysts have 2 different cell types - trophoblast, which becomes the placental structure, and inner cell mass, which becomes the developing organism
What is the role of the aminon?
the amnion lies in the chorion and produces amniotic fluid
What is the role of the yolk sac?
supports the embryo before the placenta is estbalished
What are the 3 primary germ layers of the arhenteron?
the ecto, meso and endoderm
What does the ectoderm become?
epidermis, hair, nails and epithelia of the nose, mouth, and anal canal, as well as the lens of the eyes, and nervous system including the adrenal medulla
What does the mesoderm become?
musculoskeletal, circulatory and excretory systems, and also gives rise to the gonads and the muscular and connective tissue layers of the digestive tracts and respiratory systems as well as the adrenal cortex
What does the endoderm become?
becomes the epithelial lining of the respiratory an digestive tracts, and parts of the pancreas, thyroid, bladder, and distal urinary tracts
What is neurulation?
the development of the nervous system begins after the formation of the 3 germ layers
How does the neural tube form?
the neural folds fuse to form the neural tube, which becomes the CNS
What do the neural crest cells become?
it becomes the peripheral Nervous system (sensory ganglia, autonomic ganglia, adrenal medulla, and Schwan cells) as well as specific cell types in other tissues (calcium-producing cells of the thyroid, melanocytes in the skin, and others)
What are teratogens?
substances that interfere with development causing defects or death of the developing embryo. teratogens include alcohol, certain prescription drugs, viruses, bacteria, and environmental chemicals.
What are the 3 classifications of stem cells?
totipotent, pluripotent, and mutlipoetent cells
What are totipotent stem cells able to differentiate into?
able to differentiate into all cell types including the 3 germ layers and placental strictures
What are pluripotent stem cells able to differentiate into?
able to differentiate into all cell types including the 3 germ layers and their derivatives
What are multipotent stem cells able to differentiate into?
able to differentiate only into specific subsets of cell types
What does an autocrine signal act on?
autocrine signal acts on the same cells that release the signal
What does a paracrine signal act on?
paracrine signals act on the cells in the local area via diffusions
What does a juxtacrine signal act on?
juxtacrine signal acts through direct stimulation of the adjacent cells, but the signal does not spread through diffusion
What does an endocrine signal act on?
endocrine signal acts on distant tissues after traveling through the bloodstream
When is apoptosis useful?
for sculpting certain anatomical structures such as removing the webbing between digits and a perforate anus
What are the functions of the placenta?
fetal hemoglobin (has a higher affinity than adult blood), nutrients, gas (CO2 and O2), and waste exchange, serve as immune protection against pathogens, antibodies are transferred from mother to child and secrete estrogen, progesterone, and human chorionic gonadotropin hormones
What is the diff b/w the umbilical artery and vein?
umbilical arteries carry deoxygenated blood from the fetus to the placenta; the umbilical vein carries oxygenated blood from the placenta back to the fetus
What is the diff b/w fetal and adult circulatory system?
the fetal circulatory system has shunts, and the right side of the heart is at higher pressure during prenatal life than the left side so that blood will shunt from the pulmonary circulation to the system circulation
What are the 3 fetal shunts?
the foreman oval, ductus arteriosus and ductus venosus
What does the foreman oval shunt bypass?
the foreman oval connects the right atrium to the left atrium, bypassing the lungs
What does the ductus arteriosus oval shunt bypass?
the ductus arteriosus connects the pulmonary artery to the aorta, bypassing the lunges
What does the ductus venosus shunt bypass?
the ductus venosus connects the umbilical veins to the inferior vena cava, bypassing the liver
What happens during the first trimester?
organogenesis occurs - development of the heart, eyes, gonads, limbs, liver, and brain
What happens during the second trimester?
growth continues, the movement begins, the face becomes distinctly human and the digits elongate
What happens during the third trimester?
rapid growth and brain development continues, and there is a transfer of antibodies to the fetus
What causes uterine contractions?
release of prostaglandins and oxytocin
What is the role of estrogen and progesterone?
during pregnancy, the placenta produces estrogen and progesterone to maintain the endometrium
What is incomplete regeneration?
occurs when newly formed tissues are not identical in structure and function to those injured or lost tissues.
What are the 3 cell divisions of embryo formation?
after the first division, the embryo consists of a solid ball of cells known as a morula, then a following center forms, creating the blastula. finally, as the cells begin to differentiate into the 3 germ layers, the embryo is considered a gastrula
What is the last organ to form in the fetus?
the lungs because the fetus is suspended in amniotic fluid, thus, blood exchange is bypassed the pulmonary circulation into system circulation
