Exam 2 Flashcards
(28 cards)
Main consequence of loss of follicles during menopause
Without follicular cells (no granulosa and no techa cells) the hormones secreted by these cells will not be present. Therefore, there will be no estradiol and no inhibin produced. Because granulosa and teca cells are not present, they cannot be converted into luteal cells. Therefore, Progesterone will not be secreted.
Because Progesterone is not present, the negative feedback in the hypothalamus that usually occur during the luteal phase will not be active. Therefore, the hypothalamus will continue producing GnRH at high levels.
The GnRH produce will induce production of LH and FSH. Because inhibin will be highly reduced, the FSH secretion from the pituitary will not be blocked. Therefore, the FSH levels will be very high.
These changes in hormonal levels will produce physiological consequences of menopause in women (Genital atrophy. Decreased secretion by the reproductive tract. Modification of lipid metabolism and of the vascular walls. Increase in the physiological loss of bone (osteoporosis).) These consequences are a combination of lack of estrogen, lack of progesterone and high levels of LH and particularly FSH in the blood.
The 2-cell, 2-gonadotropin Model
preparation of follicle for ovulation
synthesis of LH receptors by granulosa cells, LH surge
theca cells
produces testosterone
LH receptors to granulosa receptors for converting testosterone to estradiol
granulosa cells
produce estrogen
FSH receptors
amplification
amplified to produce many molecules
Steriodgenesis
pregnelonone for transport of cholesterol in mitochondria
aromatase for testosterone to estradiol
rhythmic environment
All living organisms inhabit a rhythmic environment. The daily 24 h rotation of the earth on its axis. The 365 day orbit of the earth around the sun. Animal species should adapt and predict these changes.
spring seasonal breaders
reproduce only at times when nutritional conditions favor lactation and growth of newborn
Mention three type of mechanisms by which transcription factors can be activated
A) the transcription factor is suddenly synthesized. B) The transcription factor binds and activator (such as progesterone) and then is activated. C) The transcription factor is modified by phosphorylation (for example CREB is phosphorylated by PKA and then becomes activated).
Do steroid receptors behave as transcription factors?
Steroid receptors when activated by the appropriate hormone act as transcription factors.
Steps of fertilization
I) Sperm binding to the Zona pellucida.
II) Penetration of the zona pellucida
III) Sperm binding to the oolema (oocyte plasma membrane)
IV) Fusion of the sperm plasma membrane with the oolema.
V) Egg activation: Increase in calcium
VI) Cortical granule exocytosis.
VII) Plasma membrane block to polyspermia.
VIII) Zona Pellucida block to polyspermia.
IX) Inhibition of cdk1 by destruction of cyclin
X) Resumption of meiosis 2.
XI) Sperm chromosomes decondensed.
XII) Formation of Male and Female Pronucleus.
XIII) Independent replication of Male and Female Chromosomes.
XIV) Syngamy.
XV) First mitotic division.
syngamy
I) Formation of male and female pronucleus.
II) Duplication of chromosomes.
III) Interdigitation of nuclear envelopes.
IV) Nuclear envelope of both male and female pronucleus breakdown.
V) Chromosomes from the egg and the sperm align on a single metaphase spindle.
parthenogenesis
Activation of the egg without fertilization by the sperm
nuclear cloning
1) Oocyte nucleus is removed.
2) Somatic cell is fused with the oocyte.
3) Oocyte is activated by parthenogenesis (for example adding Calcium from outside).
stem cells
1) Cells from the blastocyst inner cell mass.
2) Totipotent germ cells (which in the gonads will later become sperm and oocytes).
3) Reprogramming of somatic cells with four genes that convert them in stem cells.
main system in the cell involved in secretion
golgi apparatus
block to polyspermy
2 main mechanisms: zona reaction & plasma membrane polyspermy block
in the case of the plasma membrane block to polyspermy, incorporation of cortical granule membrane to the oolema, change property off egg plasma membrane and block other sperm to fuse with egg
regulated by calcium
MPF
complex formed by cDK and cyclins
high during metaphase 2 arrest, as soon as the egg is fertilized, the activity of MPF declines. , regulates formation of male and female pronucleus
inactivated by destruction of cyclin
reproductive technology
assisted reproduction, stem cell research, cloning
tubal factor infertility, endometriosis
regulation of reproduction
neural control exerted by simple neural reflexes (nerves that release neurotransmitters directly to target) and neuroendocrine reflexes (neurohormone enters blood, act on target)
The Hypothalamus-hypophyseal Portal System
connection between hypothalamus and anterior lobe of pituitary.
reproductive hormones
hypothalamus: GnRH
pituitary: LH and FSH
gondads: steroids, inhibin
follicular phase
regression of CL to ovulation (20%)
follices
estradiol
luteal phase
ovulation to regression of CL
CL
progesterone
