Biology Chapter 3: Embryogenesis and Development (2 Stars) Flashcards
______ is the joining of a sperm and an ovum.
Fertilization
Where does fertilization take place?
It usually occurs in the ampulla of the fallopian tube.
The sperm uses _______ enzymes to penetrate the corona radiata and zona pellucida.
acrosomal
Once it contacts the oocyte’s plasma membrane, the sperm establishes the acrosomal apparatus and injects its _________
pronucleus
When the first sperm penetrates, it causes a release of ________, which prevents additional sperm from fertilizing the egg and increases the metabolic rate of the resulting diploid zygote. This is called the cortical reaction.
calcium ions
Fraternal (dizygotic) twins result from the fertilization of two eggs by ________ sperm. Identical (monozygotic) twins result from the splitting of a _____in two. Monozygotic twins can be classified by the placental structures they share (mono- vs. diamniotic, mono- vs. dichorionic).
two different
zygote
______ is defined as the early divisions of cells in the embryo. These mitotic divisions result in a larger number of smaller cells, as the overall volume does not change.
Cleavage
The ______ becomes an embryo after the first cleavage because it is no longer unicellular.
zygote
________ cleavage results in cells that are capable of becoming any cell in the organism, while determinate cleavage results in cells that are committed to differentiating into a _______ cell type.
Indeterminate
specific
The ________ is a solid mass of cells seen in early development.
morula
The ________ has a fluid-filled center has two different cell types, including trophoblasts (which become placental structures) and the inner cell mass (which becomes the developing organism).
blastula (blastocyst)
The blastula implants in the _______ and forms the placenta.
endometrial lining
The chorion contains chorionic villi, which penetrate the endometrium and create the interface between ______ and ______blood.
maternal
fetal blood.
Before the placenta is established, the embryo is supported by the ______.
yolk sac.
The ________ is involved in early fluid exchange between the embryo and the yolk sac.
allantois
The amnion lies just inside the _______ and produces amniotic fluid.
chorion
The developing organism is connected to the ______ via the umbilical cord.
placenta
During gastrulation, the archenteron is formed with a blastopore at the end. As the archenteron grows through the blastocoel, it contacts the opposite side, establishing three primary ______ layers.
germ layers
The ________ becomes epidermis, hair, nails, and the epithelia of the nose, mouth, and anal canal, as well as the nervous system (including adrenal medulla) and lens of the eye.
ectoderm
The __________ becomes much of the the musculoskeletal, circulatory, and excretory systems.
mesoderm.
Also gives rise to the gonads and the muscular and connective tissue layers of the digestive and respiratory systems, as well as the adrenal cortex.
The ________ becomes much of the epithelial linings of the respiratory and digestive tracts, and parts of the pancreas, thyroid, bladder, and distal urinary tracts.
endoderm
Neurulation, or development of the nervous system, begins after the formation of the # ____ germ layers.
3 germ layers.
The notochord induces a group of overlying _____cells to form neural folds surrounding a neural groove.
ectodermal
The neural folds fuse to form the neural tube, which becomes the __________.
central nervous system.
The tip of each neural fold contains neural crest cells, which become the ________ (sensory ganglia, autonomic ganglia, adrenal medulla, and Schwann cells) as well as specific cell types in other tissues (calcitonin-producing cells of the thyroid, melanocytes in the skin, and others).
peripheral nervous system
_______ are substances that interfere with development, causing defects or even death of the developing embryo.
Teratogens
include alcohol, certain prescription drugs, viruses, bacteria, and environmental chemicals.
________ occurs as a result of determination and differentiation.
Cell specialization
________ is the commitment to a specific cell lineage, which may be accomplished by uneven segregation of cellular material during mitosis or by morphogens, which promote development down a specific cell line.
Determination
To respond to a specific morphogen, a cell must have competency.
Differentiation refers to the changes a cell undergoes due to __________ to take on characteristics appropriate to its cell line.
selective transcription
______are cells that are capable of developing into various cell types.
Stem cells
______ cells are able to differentiate into all cell types, including the three germ layers and placental structures.
Totipotent
_______ cells are able to differentiate into all three of the germ layers and their derivatives.
Pluripotent
Multipotent cells are able to differentiate _________
only into a specific subset of cell types.
Cells communicate through a number of different signaling methods. An inducer ______ factors to promote the differentiation of a competent responder.
releases
______ signals act on the same cell that released the signal.
Autocrine
_______ signals act on cells in the local area.
Paracrine
Juxtacrine signals act through
direct stimulation of the adjacent cells.
Endocrine signals act on ______ tissues after traveling through the bloodstream.
distant
If two tissues both induce further differentiation in each other, this is termed _________
reciprocal induction.
Signaling often occurs via ________.
gradients.
Apoptosis is__________ via the formation of apoptotic blebs that can subsequently be absorbed and digested by other cells.
programmed cell death
Apoptosis can be used for sculpting certain anatomical structures, such as removing the webbing between digits.
_________ capacity is the ability of an organism to regrow certain parts of the body.
Regenerative
The liver has high regenerative capacity, while the heart has low regenerative capacity.
_______ is the result of multiple molecular and metabolic processes; most notably, the shortening of telomeres during cell division.
Senescence
Nutrient, gas, and waste exchange occurs at the _______
placenta
Oxygen and carbon dioxide are _______ exchanged due to concentration gradients.
passively
Fetal hemoglobin (HbF) has a ______ affinity for oxygen than adult hemoglobin (primarily HbA), which also assists in the transfer (and retention) of oxygen into the fetal circulatory system.
higher
The placental barrier also serves as_______ against many pathogens, and antibodies are transferred from mother to child.
immune protection
The placenta serves ______ functions, secreting estrogen, progesterone, and human chorionic gonadotropin (hCG).
endocrine
The umbilical arteries carry ___________ blood from the fetus to the placenta; the umbilical vein carries __________ blood from the placenta back to the fetus.
deoxygenated
oxygenated
The ________ connects the right atrium to the left atrium, bypassing the lungs.
foramen ovale
The ductus arteriosus connects the _______ to the aorta, bypassing the lungs.
pulmonary artery
The ductus venosus connects the _______ to the inferior vena cava, bypassing the liver.
umbilical vein
In the first trimester, _______ occurs (development of heart, eyes, gonads, limbs, liver, brain).
organogenesis
In the _______ trimester, tremendous growth occurs, movement begins, the face becomes distinctly human, and the digits elongate.
second
In the third trimester, rapid growth and brain development continue, and there is transfer of ______to the fetus.
antibodies
During birth, the cervix ____ out and the amniotic sac ruptures.
thins
Then, uterine contractions, coordinated by prostaglandins and oxytocin, result in birth of the fetus. Finally, the placenta and umbilical cord are expelled.
