Menstrual Cycle, Fertilization & Development, Birth

Question 1

What does LH do in the menstrual cycle? (2 functions)

Answer 1

-Stimulates ovulation
-Supports the corpus luteum

Question 2

what day does LH spike in the menstrual cycle?

Answer 2

During day 14 of the menstrual cycle a spike of LH will occur, causing the secondary oocyte to burst from the follicle

Question 3

How do hormones control endometrial development?

Answer 3

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)

Question 4

What hormones are released by the follicle?

Answer 4

Estrogen- develops endometrium lining

Question 5

What hormones are released by the Corpus luteum?

Answer 5

Estrogen and Progesterone -prevents uterine contractions

Question 6

What hormones are released by the chorion layer?

Answer 6

HCG (Human gonadotropic hormone) -Maintains the corpus luteum for the first three months of pregnancy

Question 7

How do hormones control the menstrual cycle? Progesterone

Answer 7

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

Question 8

How do fraternal vs. identical twins form

Answer 8

Identical twins- A single egg fertilized by a single sperm splits into
Fraternal twins- Separate eggs fertilized by separate sperm

Question 9

What is mitosis, when is it used?

Answer 9

One round of cell division by a parent cell that creates 2 identical diploid daughter cells. used to create somatic(body) cells

Question 10

What is meiosis, when is it used?

Answer 10

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

Question 11

What are the stages of mitosis?

Answer 11

(IP-MAT) Interphase-Prophase-Metaphase-Anaphase-Telophase- Cytokinesis

Question 12

What is the following stage of mitosis:
“All chromosomes are duplicated. 46 pairs of chromatids.”

Answer 12

Interphase

Question 13

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”

Answer 13

Prophase

Question 14

What is the following stage of mitosis:
“Chromosomes line up at the equatorial plate. spindle fibers attach to each centromere”

Answer 14

Metaphase

Question 15

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”

Answer 15

Anaphase

Question 16

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”

Answer 16

Telophase

Question 17

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 “

Answer 17

Cytokinesis

Question 18

what is the order of events in fetal development?

Answer 18

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

Question 19

what is Gastrulation?

Answer 19

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

Question 20

What structures develop from the endoderm?

Answer 20

Liver, pancreas, thyroid, parathyroid, bladder, lining of digestive system, lining of respiratory system

Question 21

What structures develop from the ectoderm?

Answer 21

Skin, Hair, fingernails, sweat glands, nervous system, brain, lens, retina, cornea, inner ear, cochlea, semi-circular canals, teeth, inner lining of mouth

Question 22

What structures develop from the mesoderm?

Answer 22

Muscles, blood vessels and blood, kidneys and reproductive structures, connective tissues, cartilage, bones

Question 23

What is the function of the placenta?

Answer 23

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.

Question 24

How dose the placenta deliver oxygen and nutrients to the fetus?

Answer 24

villi in the placenta exchange gas and neturients through osmosis

Question 25

How do hormones control the menstrual cycle? estrogen

Answer 25

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.

Question 26

How do hormones control the menstrual cycle? FSH

Answer 26

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

Question 27

How do hormones control the menstrual cycle? LH

Answer 27

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.