Chapter 3 - Reproductive System Flashcards
foramen ovale
A shunt in the fetus that connects blood flow from the right atrium directly to the left atrium (to bypass blood flow to the lungs)
ductus arteriosus
Shunts leftover blood from the pulmonary artery to the aorta, this allows the deoxygenated blood to travel to the lower half of the fetus’s body to the placenta
Ductus venosus
Shunts highly oxygenated umbilical venous blood from the placenta directly into the inferior vena cava
What is the purpose of shunts in a fetus?
They direct blood away from the liver and lungs, so that these organs can develop
Factors that can induce apoptosis
-DNA damage
-Development
-Viral Infections
-Stress (deprivation of nutrients & oxygen)
-Production of reactive oxygen species (ROS)
Characteristics of apoptotic cells
Condensation of nuclei, cell shrinkage, blebbing of the membrane, fragmentation of cell & nucleus, formation of apoptotic bodies that are eventually digested by macrophages
what is necrosis?
Uncontrolled cell death in response to extreme stress/trauma
What is apoptosis?
Controlled cell death via apoptotic signaling
What is determinate cleavage?
The division of cells which results in the cell committing to a particular lineage/type.
What is indeterminate cleavage?
The mitotic division of cells which doesn’t commit the cell to a specific line. This occurs when the zygote undergoes several mitotic divisions to become a morula.
Pathway from fertilized egg to gastrulation
fertilized egg (zygote) –> 2-cell embryo –> 4-cell embryo –> morula (8 cells) –> blastocyst –> gastrula
What is a morula?
It is the 8-cell stage of development
What is a blastocyst?
A hollow ball of cells with a fluid filled inner cavity. The inner cavity is which the organism develops, while the outer layer of trophoblast cells forms the developing placenta
How are monozygotic (identical) twins formed?
When a single zygote splits into two and then implants in a different region of the uterus.
What is gastrulation? When does it happen?
It is when a blastocyst develops 3 distinct germ cell layers through invagination of itself. This happens week 2 post fertilization.
Which structures of the body arise from the ectoderm?
epidermis, nails, epithelia of nose, mouth, lens of eye, all of nervous system, and inner ear
Which structures of the body arise from the endoderm?
epithelial linings of digestive & respiratory tracts, pancreas, thyroid, bladder, liver, gallblader
Which structures of the body arise from the mesoderm?
Dermis, musculoskeletal system, circulatory system, excretory organs, gonads (genitalia), connective tissue, muscle tissue of digestive & respiratory organs
What is the process of neurulation and when does it occur?
It begins of week 3 and it is when the nervous system starts developing.
Describe the steps of neurulation.
- The notochord forms from the mesoderm.
- The notochord induces the ectoderm to form the neural plate above.
- The neural plate folds inward, surrounding a middle neural groove.
- The grooves invaginate more until they fuse to form the neural tube.
- Neural crest cells from the folds migrate outwards to form the PNS.
What are teratogens?
Substances that interfere with development of the fetus.
At what stage/s of development are the cells considered totipotent?
Fertilization stage up until the morula stage is considered totipotent. Meaning that each cell can “possibly” develop into a new individual.
At what stage/s of development are the cells pluripotent?
At the blastocyst stage and gastrula stage where the stem cells make up the three germ layers. This is because these cells can differentiate into any cell type in any tissue/organ system.
what are inducers?
Specialized cells which release growth factors that signal to other cells to divide and differentiate into a specific cell type (such as a neuron)
During induction, how does the inducer cell communicate with the other cells?
It communicates directly through gap junctions with the other cells or indirectly by releasing signals into the ECM which act on cells in the localr region.
