BIOL 201 Lecture Notes - Corpus Luteum, Ovarian Follicle, Luteal Phase

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11 Feb 2013

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Stimulates development (division) of follicle cells surrounding the oocyte. Developing follicle cells secrete oestrogen: stimulates proliferation of endometrium and its blood supply, stimulates pituitary gland to secrete luteinising hormone (lh) Inhibits further secretion of fsh by negative feedback. Mature ovarian follicle bursts and releases a 2 oocyte (not an ovum: happens once a month, menstrual cycle 28days, each ovary alternatively releases a 2 oocyte every 56days ( 56/2) Lh forms the corpus luteum from ruptured follicle. Progesterone is responsible for: proliferation of endometrium and its blood supply, development of nutrient fluid glands in uterus lining. Corpus luteum degenerates (due to inhibition of lh) Shedding of the endometrium due to low levels of progesterone and oestrogen. Fsh is not inhibited anymore cycle starts again. Placenta after 3mo (because the corpus luteum degenerates: prevents menstruation and maintains endometrium, thickens cervical mucus impermeable to sperm, prepares uterus for implantation. Remember: oestrogen contraction while progesterone contraction of uterus.

Related Questions

1. The site of implantation of a fertilized ovum is

A.The uterus

B..	The ovaries

C.	The vag ina

D.	The cervix

2. Which statement correctly describes the secretory phase of the uterine (menstrual) cycle?

A.	Follicle stimulating hormone stimulates proliferation of the endometrium

B.	During this phase, the endometrium detaches and sheds

C.	Progesterone stimulates the endometrium to prepare for implantation

D.	Decreased progesterone levels cause the endometrial cells to die

Which events in the monthly female reproductive cycle occur simultaneously?

A. Menstruation and the estrogen surge

B.	Endometrial proliferation and development of the vesicular follicle

C.	Degeneration of the corpus luteum and increased LH and FSH secretion

D.	The secretory phase in the uterus and decreased progesterone levels

Please give some explanations, thanks.

Terms: 1, 14, 28, corpus luteum, estradiol, follicular,GnRH, inhibitory, LH surge, luteal, ovulatory, progesterone,regresses, stimulatory

The ovarian cycle refers to the recurrent, cyclic changes inhormone secretion and follicle/oocyte development that occurroughly every 28 days in the 'typical' woman. The ovarian cycle canbroadly be divided into 3 sequential phases, the first, or_____________ phase which precedes or comes before release of theegg, the middle or ____________ phase during which the egg isactually released, and the final or _______________ phase whichcomes after the egg is released and lasts until the next cyclebegins.

Day 1 of the follicular phase marks the beginning of a newcycle. During the follicular phase, as the name implies, a 'cohort'or small group of follicles (i.e. the structures in the ovary inwhich the oocytes are maturing) begin to grow, develop and preparetheir oocytes for release in response to FSH stimulation from theanterior pituitary. These follicles are the main hormone-secretingstructures in the ovary and the main hormone they are secreting is____________. Early in the phase, when estrogen levels are low, theestrogen exerts ____________feedback control on thehypothalamic-pituitary axis and keep GnRH, LH and FSH levelsrelatively low. Eventually, a single follicle assumes dominance,outgrows and out develops the others, and begins to secrete largerand larger amounts of estrogen. When estrogen levels becomesufficiently high, estrogen's effect at the hypothalamus becomestransiently ______________, causing increases in GnRH secretionthat trigger a mid-cycle _______________.

Right around mid-cycle or around day _________ of the 'typical'__________ day long cycle, under the influence of high levels of LHproduced by the LH surge, the wall of the dominant follicle thinsand eventually ruptures, releasing the egg. This release of the eggis termed ovulation, hence the portion of the cycle immediatelypreceding and including ovulation is termed the ovulatory phase.Another effect of LH is that it luteinizes the follicle, producingchanges in the follicle cells that enable the granulosa cells tosecrete ____________ in addition to estratiol.

The final phase of the ovarian cycle, the luteal phase, beginsimmediately after ovulation and lasts until day 1 of the nextcycle. The luteal phase is characterize by the presence andfunctioning of a _____________. This is the name for the structurethat develops from the follicle after it has lost its egg. Theremainder of the follicle involutes or falls in upon itself,becomes highly vascularized and its luteinized' cells secrete highconcentrations of progesterone in addition to estradiol. Theprogesterone exerts an overriding inhibitory effect on hypothalamic__________ secretion at this time. In the absence of pregnancy, theCL will remain highly active for ~12 days before it __________, orbegins to die off and cease its hormone-secreting activities. CLregression causes a rapid drop in the concentrations of estrogenand progesterone secretion over the next 2 days that will result inshedding of the endometrial lining of the uterus and menstruation.Day 1 of menstruation coincides with and serves as the externalindicator that day _________ of a new ovarian cycle has begun.

rubyshark46

106) A fertilized egg must embed in this organfor pregnancy to occur.

A) vagina

B) uterus

C) ovaries

D) myometrium

E) oviduct

107) The opening of the uterus is referred toas

A) the endometrium.

B) the oviduct.

C) the cervix.

D) the fimbriae.

E) the clitoris.

108) When the oocyte is released from theovary, it is transported to the uterus by the

A) fimbriae.

B) flagella.

C) oviduct.

D) ductus deferens.

E) endometrium.

109) Prior to the onset of lactation, themammary glands are prepared for the production of milk by

A) the hormonal action of estrogen andprogesterone.

B) the completion of ovulation.

C) degeneration of the corpus luteum.

D) deactivation of FSH, LH and GnRH.

E) synthesis of FSH.

110) Which of the stages in the diagramabove occurs due to a surge of LH midway through the ovariancycle?

A) A

B) B

C) C

D) D

E) E

111) Which of the stages in the diagram abovedegenerates if the fertilized egg does not embed in the uterus?

A) A

B) B

C) C

D) D

E) E

112) At the beginning of each ovarian cycle,which of the following hormones causes the development of a primaryoocyte?

A) estrogen

B) LH

C) prolactin

D) progesterone

E) FSH

113) If pregnancy does occur, a layer oftissue from the embryo called the chorion begins to secrete thehormone

A) GnRH.

B) estrogen.

C) FSH.

D) hCG.

E) LH.

114) Which of the following methods ofenhancing fertility involves the placement of sperm andunfertilized eggs into the oviduct?

A) artificial insemination

B) in vitro fertilization

C) gamete intrafallopian transfer (GIFT)

D) hysteroscopy

E) zygote intrafallopian transfer (ZIFT)

114) Drugs like Viagra, Cialis and Levitra arenot aphrodisiacs, meaning that they do not cause an erection,rather they function by

A) increasing LH and FSH release.

B) promoting blood inflow into the penis.

C) increasing the net movement of calcium ionsinto vascular smooth muscles in the penis.

D) stimulating sensitivity in peniletissues.

E) decreasing inhibin production.

115) If fertilization does not occur followingrelease of the egg by the ovary, then the ________ will degenerateapproximately two weeks after ovulation.

A) primary oocyte

B) oviduct

C) endometrium layer

D) corpus luteum

E) All of the above are correct.

116) Chemicals or particles in air that haveadverse effects on living organisms is termed

A) acid rain.

B) eutrophication.

C) pollution.

D) global warming.

E) dentrification.

117) Gases such as nitrous oxide and carbondioxide are called greenhouse gases because

A) they block sunlight from reaching theEarth.

B) they block specific wavelengths of sunlightfrom penetrating.

C) these gases permit sunlight to enter buttrap the heat energy in the atmosphere.

D) they block both sunlight and heat energyfrom penetrating the atmosphere.

E) they stimulate photosynthesis in mostplants.

118) The ozone layer can be destroyed bypollutants such as

A) sulfur dioxide.

B) halons and CFCs.

C) carbon monoxide.

D) hydrocarbons and nitrogen oxides.

E) carbon dioxide and oxygen.

119) The main human activities that haveraised atmospheric CO2 levels are

A) succession and adaptive radiation.

B) home development on grasslands andwetlands.

C) drainage of wetlands areas along rivers andoceans.

D) deforestation and burning fossil fuels.

E) really negligent because CO2levels have risen and fallen naturally regardless of humanactivity.

120) "Earth's fever" is in reference to

A) a rise in the temperature of the Earthbelieved to be due to greenhouse gases.

B) the potential pandemics that manyscientists believe could occur at any time with the burgeoninghuman population.

C) current disease epidemics, mainly thoseassociated with disease spreading from animals like birds andlivestock to humans.

D) the Earth's crust.

E) potential volcanic eruptions in locationsthat have not experienced such activity in many years.

121) Certain gases in the upper atmosphereallow sunlight to pass through to the Earth's surface, but preventheat from escaping. This is known as

A) global positioning.

B) desertification.

C) the greenhouse effect.

D) thermal inversion.

E) eutrophication.

122) The largest hole in the ozone layeroccurs in the stratospheric layer over

A) the Amazon rainforests.

B) the eastern coast of the United States.

C) the western coast of the United States.

D) Africa and South America.

E) Antarctica.

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BIOL 201 Lecture Notes - Corpus Luteum, Ovarian Follicle, Luteal Phase

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