Biology Questions and Answers

Biology Questions and Answers

21. How does the hypophysis-
    corpus luteum negative
    feedback work? What is the
    name given to the atrophied
    corpus luteum after this
    feedback process?

After ovulation the estrogen and
progesteroluteum inhibit thne secretions fre hypophyseal FSH om the corpusand
LH secretions (this happens by inhibition

of GnRH, ghormone, a hypothalamiconadotropin-releasing hormone). (^)
The blood concentration oadenohypophyseal hormones fallsf these (^) to
basal levels again. As LH lowers the
corpus lutbecomes atrophic aeum (luteum nd turns into means “yellow”)the
corpus albicans (“white”). With the
regression oproduction of the corpus luteum thef estrogen and
progesterone ceases.

22. In hormonal terms why
    does menses occur?

Menses is the endometrial monthly

desquamation that occurs as thestrogen and progesterone levels falle (^)
after the regression of the corpus
luteum because these hormones, mainlyprogesterone, can no longer support
and maintain the thickening of the
endometrium.

23. What is the explanation
    for the bleeding that
    accompanies menses?

The hemorrhamenses occurs bge that accompaniesecause the

endometrium is a richly vascularized

tissue. Tthe uterine mucosa dhe rupture of blood vessels ofuring the

menstrual desquamation causes the

bleeding.

24. Which are the phases of
    the menstrual cycle?
    The menstrualmain phases: the follicular (or cycle is divided into two
    menstrual) phase and the luteal (or
    secretory) phase.
    The menstrual phase begins at the first

day of menses an(around the 14th d lastsday). T until ovulationhe luteal phase (^)
begins after ovulation and ends when
menses begins (around the 28th day).

25. Including main events and
    hormonal changes how can
    the menstrual cycle be
    described?
    One can imagine a cycle like an analog

clock atbeginning and the end of the menstrual which at 0 o’clock is the (^)
cycle and that 6 o’clock corresponds to
the 14h day of the cycle.
At 0 o’clock the menstrual cycle bemenses angins and FSH bld so theood (^)
level begins to increase. Around 2
o’clock the maturing action are already secrfollicleseting estro under FSHgen
and the endometrium is thickening.
Around 3 o’clock estrostimulating the increase ogen is intenselyf LH blood
level. At 6 o’clock (the 14th day) LH is
at its maximum concalso at high levels to pentration anromote ovulation,d FSH (^)
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