[Biology] Ch.3: Embryogenesis and Development Flashcards
What happens after sperm penetrate through the cell membrane
A release of calcium ions (cortical reaction)
What’s the difference between dizygotic (fraternal) and monozygotic (identical) twins
dizygotic = two different eggs released during one ovulatory cycle, monozygotic = a single zygote splits into two
In the process of moving to the uterus for implantation the zygote undergoes [ 1 ] in a process called cleavage
Rapid mitotic cell divisions
Does the size of the embryo change during early cleavage
No. The size remains unchanged
Explain the difference between indeterminate and determinate cleavage
- Indeterminate = cells that can still develop into complete organisms
- Determinate = results in cells with fates that are already determined (the cells are committed to differentiating into a certain cell type
After several divisions the embryo becomes [ 1 ] known as a morula
A solid mass of cells
What is a blastula
A hollow ball of cells with a fluid-filled inner cavity (known as a blastocoel)
What is the mnemonic to remember what a blastula is
The blastula is an embryo with a blasted-out cavity
What is the difference between the trophoblast cells and the inner cell mass
Trophoblast cells surround the blastocoel and gives rise to the chorion and later the placenta whereas the inner cell mass protrudes into the blastocoel and gives rise to the organism itself
What does the umbilical cord consist of
Two arteries and one vein encased in a gelatinous substance
What is the difference between the substances carried in the umbilical vein and arteries
- Vein = freshly oxygenated blood rich with nutrients from the placenta to the embryo
- Arteries = deoxygenated blood and waste to placenta for exchange
What is the allantois
The fluid that serves as a shock absorber during pregnancy and lessens the impact of maternal motion on the developing embryo
What is gastrulation
When the cell mass implants and three distinct cell layers are generated
What are the three primary germ cell layers from outermost to innermost layer
Ectoderm, mesoderm, and endoderm
What does ectoderm give rise it
To integument (including the epidermis, hair, nails, and the epithelial of the nose, mouth, and lower anal canal)
What does the mesoderm develop into
Into several different systems including the musculoskeletal, circulatory, and most of the excretory systems
What does the endoderm form
The epithelial linings of the digestive and respiratory tracts, including the lungs
What would happen if neurulation couldn’t occur
The nervous system wouldn’t be able to develop
The notochord is like a [ 1 ]
Primitive spine
What are teratogens
Substances that interfere with development, causing defects or even death of developing embryo
True or False: teratogens have the same effect on every embryo or fetus
False. They will not have the same effect on every embryo or fetus
What are common teratogens
Alcohol, prescription drugs, viruses, bacteria, and environmental chemicals
What’s the effect of maternal folic acid deficiency
It may prevent complete closure of the neural tube resulting in spina bifida (parts of the nervous system are exposed to the outside world or covered with a thin membrane)
What are morphogens
Molecules that may cause nearby cells to follow a particular development pathway
What is the difference between determination and differentiation
- Determination = commitment to a particular cell type
- Differentiation = when a cell produces the products to carry out the function of their cell type
What is the difference between totipotent, pluripotent, and multipotent stem cells
- Totipotent = can ultimately differentiate into any cell type
- Pluripotent = can differentiate into any cell type except for those found in placental structures
- Multipotent = can differentiate into all of the cells within a particular group (ex: hematopoietic stem cells)
What’s the difference between autocrine, paracrine, juxtacrine, and endocrine signaling
- Autocrine = signals act on the same cell that secretes the signal
- Paracrine = signals act on cells in the local area
- Juxtacrine = signals with a cell that’s directly stimulates receptors on an adjacent cell (usually doesn’t involve diffusion)
- Endocrine = signals involve secreted hormones that travel through the bloodstream
Why doesn’t apoptosis lead to tissue damage the way necrosis does
During apoptosis the cell divides into many self contained pieces called apoptotic blebs that can be digested by other cells but in necrosis internal substances can be leaked, causing irritation of nearby tissues or even an immune response
What is senescence
Biological aging that occurs as changes accumulate
What is the difference between fetal hemoglobin and maternal hemoglobin
Fetal hemoglobin has a higher affinity for oxygen than maternal hemoglobin
How does the placenta serve as immune protection
Antibodies crossing the membrane serve a protective function
Why does the placenta qualify as an endocrine organ
It produces progesterone, estrogen, and human chorionic gonadotropin (hCG) all of which are essential for maintaining pregnancy
The [ 1 ] and [ 2 ] both don’t serve significant functions prior to birth so the fetus constructs shunts to [ 3 ] while they develop
1) lungs 2) liver 3) actively direct blood away from these organs
What happens by the end of the first trimester
Most of the organs have formed, the brain is fairly developed, and the embryo is known as a fetus (also, the heart beats)
What happens during the second trimester
The fetus undergoes tremendous growth, it begins to move in the amniotic fluid, its face takes on human appearance, and its toes and fingers elongate
What’s the relationship between the third trimester and the immune system
Antibodies are transported by highly selective active transport from the mother to the fetus (for protection against foreign mater in preparation for life outside the womb)
What are the steps of birth (or parturition)
- Cervix thins out and amniotic sac ruptures
- Strong uterine contractions result in birth
- Placenta and umbilical cord are expelled
