Menstrual Cycle, Fertilization & Development, Birth Flashcards
What does LH do in the menstrual cycle? (2 functions)
-Stimulates ovulation
-Supports the corpus luteum
what day does LH spike in the menstrual cycle?
During day 14 of the menstrual cycle a spike of LH will occur, causing the secondary oocyte to burst from the follicle
How do hormones control endometrial development?
During days 1-5 of the cycle, estrogen levels drop and the endometrium lining sheds(Flow phase). After day five the follicle begins to secret estrogen which will develop/thicken the endometrium lining until it reaches its peak thickness between days 15-28. If fertilization dose not occur, estrogen levels will drop causing contractions that shed the lining and start the cycle again., (TDLR: Estrogen controls the lining, as levels rise the lining thickens and when they drop the lining sheds)
What hormones are released by the follicle?
Estrogen- develops endometrium lining
What hormones are released by the Corpus luteum?
Estrogen and Progesterone -prevents uterine contractions
What hormones are released by the chorion layer?
HCG (Human gonadotropic hormone) -Maintains the corpus luteum for the first three months of pregnancy
How do hormones control the menstrual cycle? Progesterone
Progesterone: High levels secreted from corpus luteum prevent uterine contractions and send a (-) feed back loop that stops secretion of both LH and FSH. Low levels after the corpus luteum disintegrates signal the pituitary to secrete LH and FSH starting a new cycle
How do fraternal vs. identical twins form
Identical twins- A single egg fertilized by a single sperm splits into
Fraternal twins- Separate eggs fertilized by separate sperm
What is mitosis, when is it used?
One round of cell division by a parent cell that creates 2 identical diploid daughter cells. used to create somatic(body) cells
What is meiosis, when is it used?
Two rounds of cell division that reduce the number of chromosomes in gemmates(sex cells) and produce 4 haploid daughter cells that are genetically different from the parent cell and each other. used in gametogenesis to produce sex cells
What are the stages of mitosis?
(IP-MAT) Interphase-Prophase-Metaphase-Anaphase-Telophase- Cytokinesis
What is the following stage of mitosis:
“All chromosomes are duplicated. 46 pairs of chromatids.”
Interphase
What is the following stage of mitosis:
“Nuclear membrane begins to dissolve. Chromatin condenses into chromosomes. centrioles move to opposite poles and attach/produce spindle fibers”
Prophase
What is the following stage of mitosis:
“Chromosomes line up at the equatorial plate. spindle fibers attach to each centromere”
Metaphase
What is the following stage of mitosis:
“Spindle fibers contract, causing the chromosomes to split at each centromere. sister chromatids move to opposite ends of the cell”
Anaphase
What is the following stage of mitosis:
“chromosomes de-condense into two groups of chromatin. Nuclear membrane begins to form around each group. Centrioles dissolve their spindle fibers”
Telophase
What is the following stage of mitosis:
“Cleavage furrow “pinches” cell into separate daughter cells. Each daughter cell has a complete, independent nucleus. Each daughter cell now enters its own interphase, and the cycle continues “
Cytokinesis
what is the order of events in fetal development?
fertilization - zygote -3 to 6 days- blastocyst - implantation - gastrulation - embryonic development - Formation of Amnion, Chorion layers, yolk sac, and allantois - formation of placenta and umbilical cord - fetal development
what is Gastrulation?
The phase during embryonic development when a blastocyst transitions from a hallow ball to a structure containing three layers, the Ectoderm(outermost layer), Mesoderm(middle layer), and endoderm( innermost layer). each layer will proceed to differentiate into various cells, tissues and systems
What structures develop from the endoderm?
Liver, pancreas, thyroid, parathyroid, bladder, lining of digestive system, lining of respiratory system
What structures develop from the ectoderm?
Skin, Hair, fingernails, sweat glands, nervous system, brain, lens, retina, cornea, inner ear, cochlea, semi-circular canals, teeth, inner lining of mouth
What structures develop from the mesoderm?
Muscles, blood vessels and blood, kidneys and reproductive structures, connective tissues, cartilage, bones
What is the function of the placenta?
the placenta acts as the lungs, kidneys and small intestine of the fetus providing nutrients, allowing gas exchange between the mother and fetus, and allowing waste disposal.
How dose the placenta deliver oxygen and nutrients to the fetus?
villi in the placenta exchange gas and neturients through osmosis
How do hormones control the menstrual cycle? estrogen
During days 1-10 the follicle secrets estrogen, which thickens the endometrium lining and applies a negative feedback loop to the pituitary preventing the secretion of LH and FSH (they will drop). During days 10-12 estrogen will begin to peak and switch to a positive feedback loop with the pituitary, signalling the release of LH and FSH. estrogen levels will dip till the corpus luteum begins to secrete estrogen and progesterone, this will send a negative feedback loop to the pituitary to prevent the secretion of FSH and LH (FSH and LH levels will drop). After the corpus luteum disintegrates estrogen levels will drop, the endometrium lining will shed and the cycle will begin again.
How do hormones control the menstrual cycle? FSH
Low estrogen and progesterone levels at the beginning of the cycle will signal the pituitary to secrete FSH, the FSH will promote follicle development until estrogen levels rise and the pituitary is signalled to halt secretion. levels of FSH will remain low until estrogen and progesterone levels drop during the flow phase
How do hormones control the menstrual cycle? LH
after the follicle has developed, estrogen will spike on day 13 signalling the rapid secretion of LH. LH levels will peak on day 14 and cause the secondary oocyte to erupt from the follicle. LH levels will drop again.
