Biology Chapter 3 Embryogenesis And Development Flashcards
Where does fertilization occur?
Ampulla of the Fallopian tube
What enzymes do sperm use to penetrate the corona radiata and zona pellucida.
Acrosomal enzymes
What apparatus do sperm establish once connected to the oocyte plasma membrane?
Acrosomal apparatus
What ion is released once sperm penetrate the ovum?
Calcium
After the first cleavage division what is the new cell called?
Embryo
What is indeterminate cleavage?
Cleavage that results in a cell that is capable of becoming any cell in the organism.
What is determinate cleavage?
Cleavage that results in a cell that is only capable of being a specific cell type.
Morula
Solid mass of cells seen in early development
Blastula
Mass with a fluid filled center called a blastocoel and two different structures the trophoblast (becomes placental structures) inner cell mass (becomes the developing organism)
What is the trophoblast?
Structure within the blastula that becomes placental structure)
What is the inner cell mass?
Structure within the blastula that becomes the developing organism
What is the blastocoel?
Fluid filled center of the blastula
Where does the blastula implant?
In the endometrial lining.
What is the chorion?
An extra-embryonic membrane that develops into the placenta.
Contains chorionic villi which penetrate the endometrium and create an interface between maternal and fetal blood.
What is the allantosis?
One of two extraembryonic membranes. Involved in early fluid exchange between the embryo and the yolk sac.
The other extraembryonic membrane is the amninon.
What is the amnion?
One of two extraembryonic membranes.
Lies just inside the chorion
The amnion contains amniotic fluid which acts as a shock absorber for movements of the mother.
What does the ectoderm form?
Hair, nails, epithelial of the nose mouth and anal canal. Nervous system and the lens of the eye.
What does the endoderm form?
Epithelial linings of the respiratory and digestive tracts, parts of the pancreas, thyroid, bladder, distal urinary tracts.
What does the mesoderm form?
Musculoskeletal, circulatory and excretory systems. Gives rise to the gonads, muscular and connective tissue layers of the digestive and respiratory systems, adrenal cortex
What is neurulation and when does it occur?
Development of the nervous system. After formation of the three germ layers.
What makes up the neural tube? What does it become?
Notochord induces furrowing of ectodermal cells to form neural folds. Neutral folds fuse to form the neural tube which becomes the central nervous systems.
What makes up the neural crest cells?
What does it develop into?
Tip of the neural fold. Develops into the peripheral nervous system: sensory ganglia, autonomic ganglia, adrenal medulla and Schwann cells) specific cell types in other tissues (calcitonin producing cells of the thyroid, melanocytes in the skin)
What is a teratogen and what are examples?
Substances that interfere with development causing defects or death of the developing embryo.
Alcohol, certain prescription drugs, viruses, bacteria environmental chemicals.
What maternal conditions can affect development?
Diabetes (Increased fetal size and hypoglycemia after birth) and Folic Acid Deficiency (neural tube defects)
What is the difference between determination and differentiation?
Determination is the commitment to a specific cell lineage. Accomplished either through uneven segregation of cellular material during mitosis or with the help of Morfogen’s (promote development down a specific cell line)
Differentiation refers to the changes of cell undergoes due to selective transcription to take on characteristics appropriate to its cell line
What are the three classifications of stem cells?
Totipotent cells-Able to differentiate into all cell types including the three germ layers and placental structures.
Pluripotent cells-Able to differentiate into all three of the germ layers and their derivatives.
Multipotent cells- Able to differentiate only into a specific subset of cell types.
What are the four ways that cells communicate with each other?
Autocrine signals- Acts on the same cell that released the signal
Paracrine signals- Acts on local cells
Juxtacrine signals-Ask through direct stimulation of receptors on adjacent cells.
Endocrine signals-Acts on distant tissues after traveling through the bloodstream
What promotes differentiation? What promotes determination?
Growth factors promote differentiation. Morfogen’s promote determination.
What is reciprocal induction?
When two tissues both induce differentiation in each other.
What is regenerative capacity?
The ability of an organism to regrow certain parts of the body.
What is Senescence?
Biological aging.
The result of multiple molecular and metabolic processes most notably the shortening of telomeres during cell division.
What things are exchanged at the placenta?
Nutrients, gas, waste.
What type of affinity does fetal hemoglobin have her oxygen compared to adult hemoglobin (Hba)?
Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin.
What hormones does the placenta secrete? What endocrine role does the placenta play?
The placenta secretes progesterone, estrogen, hCG
What type of blood (oxygenated/deoxygenated) does the umbilical artery’s and veins carry?
The umbilical artery’s carry deoxygenated blood from the fetus to the placenta.
The umbilical vein carries oxygenated blood flow from the placenta to the fetus.
How does the fetal circulatory system differ from the adult circulatory system?
It has three shunts. In order to direct blood away from the liver and lungs while they develop. These organs are underdeveloped and sensitive to high blood pressures after birth.
Foramen Ovale Connects the right atrium to the left atrium (bypassing the lungs)
Ductus Arteriosis Connects the pulmonary artery to the aorta (bypassing the lungs)
Ductus Venosus Connects the umbilical vein to the inferior vena cava (bypasses the liver)
What major development occurs in the first trimester?
Organogenesis or development of the heart eyes gonads limbs liver and brain.
What development occurs in the second trimester?
Tremendous growth of the fetus, movement begins, face becomes distinctly human, digits elongate
What development occurs in the third trimester?
Rapid growth and brain development continue, transfer of antibodies to the fetus
What physiological changes occur during birth?
The cervix thins out, amniotic sac ruptures.
What coordinates uterine contractions?
Oxytocin and prostaglandins
On what day of the menstrual cycle is the oocyte ovulated?
Day 14
On day 14 of the menstrual cycle what type of oocyte is ovulated?
Secondary oocyte
After the sperm attaches to the oocyte via acrosomal apparatus, when can the pronucleus enter the oocyte freely?
After completion of meiosis two
What is the placenta, chorion, and amnion?
Placenta: An organ that develops in the uterus during pregnancy. It provides gas exchange metabolic transfer hormone secretion and fetal protection.
Chorion: The outermost of the two fetal membranes. Forms chorionic villi which initially provides nutrition to the developing embryo, later gives rise to the placenta.
Amnion: The innermost membrane that encloses the embryo, allows for nutrients to reach the fetus and waste products to be removed amniotic fluid is found inside the amnion and provides protection for the developing child.
What structures make up the umbilical cord?
Two arteries and one vein in case and a gelatinous substance
What is the yolk sac?
Supports the embryo until the placenta is functional. The site of early blood cell development
What is the umbilical cord formed from?
Remnants of the allantosis and the yolk sac
Allantois
Involved in early fluid exchange between the embryo and yolk sac.
Surrounded by the amnion.
What are the three primary germ layers?
The ectoderm mesoderm and endoderm
What is induction?
The ability of one group of cells influence the fate of nearby cells.
Mediated by chemical substances called inducers
What is selective transcription?
When only the genes needed for a particular cell type are transcribed.
Some genes are turned on while others are turned off.
Which primary germ layer is the nervous system derived from?
Ectoderm
What are the three stages of cell specialization?
Speciation, Determination,Differentiation
Speciation
The cell is reversibly designated as a specific cell type
In the stage of the cell can still become any type of cell even though it has underwent speciation
Determination
Commitment of a cell to a particular function in the future
What processes leads to determination?
Specific mRNA and protein molecules result in determination. 
Secretion of specific molecules called Morfogen caused neighboring cells to follow a particular developmental pathway.
Differentiation
Changing the structure function and bio chemistry of the cell to match the cell type
What are the different types of potency
Totipotent, pluripotent, multipotent.
What type of molecule is an inducer?
Often growth factors, Peptides that promote differentiation and mitosis in certain tissues
How long does human gestation last?
280 days
