What are the sources of estrogen?
1. ovaries (granulosa cells)
3. adipose tissue (estrone, via aromatization)
What are three types of estrogen? what is their relative potency?
estradiol > estrone > estriol
What are the functions of estrogen?
1. development of genitalia, breasts
2. endometrial proliferation
3. female fat distribution
4. growth of ovarian follicle
5. feedback inhibition of LH, FSH
6. stimulates Luteal surge
7. increases SHBP
8. decreases LDL
9. increases HDL
10. stimulates prolactin secretion
11. increases myometrial excitability
What are the sources of progesterone?
1. corpus luteum
3. adrenal cortex
What are the functions of progesterone?
1. stimulates endometrial glandular secretions and spiral artery development
2. stimulates thick cervical mucus (inhibits sperm from entering cervix)
4. increases body temperature
5. feedback inhibition of LH, FSH
6. decreases myometrial excitability
7. relaxes uterine smooth muscle
8. decreases estrogen receptor expressivity
9. prevents endometiral hyperplasia
What cells in the ovarian follicle secrete estrogen? How is this estrogen produced?
FSH stimulates the production of estrogen from androstenedione by the enzyme aromatase.
The androstenedione substrate comes from the neighboring theca cells
On what cells in the ovary does LH act? What do these cells produce?
LH stimulates the theca cells of the ovarian follicle to produce androstenedione from cholesterol.
The enzyme that catalyzes this process is desmolase
What is the ploidy of the oogonium?
What does the oogonium give rise to?
The oogonium is diploid, with 46 single chromosomes
The oogonium gives rise to the 1º oocyte
What is the ploidy of the 1º oocyte?
In what stage of development is the 1º oocyte arrested?
The 1º oocyte is diploid, with 46 pairs of sister chromatids
The 1º oocyte is arrested in prOphase of meiosis I until Ovulation.
To what does the 1º oocyte give rise?
When does this development occur?
The 1º oocyte gives rise to the 2º oocyte during ovulation.
One polar body is generated in the division of the 1º oocyte that produces the 2º oocyte. This polar body cna degenerate, or give rise to two additional polar bodies.
What is the ploidy of the 2º oocyte?
In what stage of development is the 2º oocyte arrested?
The 2º oocyte is haploid, with 23 pairs of sister chromatids.
The 2º oocyte is arrested in metaphase of meiosis II until it is fertilized.
What does the 2º oocyte give rise to? When? What is the ploidy of this new cell?
The 2º oocyte gives rise to the ovum when it is fertilized.
When the 2º oocyte is fertilized, it exits metaphase II and completes meiosis II, giving rise to an ovum that is haploid, with 23 single chromatids.
The 2º oocyte also gives rise to a polar body.
What is the name of the stage at which a fertilized egg implants in the endometrium?
The blastocyst is what implants into the endometrium.
List the names of the cells in order of phase in spermatogenesis, and the ploidy of each.
1º spermatocyte (2N)
2º spermatocyte (1N)
mature spermatozoon (1N)
What is the genetic content of a 1º spermatocyte?
The 1º spermatocyte is diploid.
It contains 46 pairs of sister chromatids
What is the genetic content of a 2º spermatocyte?
The 2º spermatocyte is haploid.
It contains 23 pairs of sister chromatids.
What is the genetic content of a spermatid?
The spermatid is haploid.
It contains 23 single chromatids.
Where does spermatogenesis take place?
In the seminiferous tubules.
where is hCG produced?
In the syncytiotrophoblast of the placenta.
The alpha subunit of hCG is structurally identical to the alpha subunit of what other hormones?
LH, FSH, and TSH
What is the function of the hCG?
To maintain the corpus luteum during the first trimester of pregnancy. The corpus luteum secrete progesterone, which is required for the maintenance of pregnancy; LH is required for the maintenance of the corpus luteum. During the first trimester, hCG from the placenta maintains the corpus luteum. It can do this because it's alpha subunit is structurally identical to that of LH. In the 2nd and 3rd trimesters, the placenta starts to produce its own progesterone and estrogen (estriol), and the corpus luteum degenerates.
What stimulates ovulation?
The LH surge.
Estrogen generally inhibits LH (and FSH) through feedback inhibition. However, once estrogen has surpasses a certain threshold, it stimulates a surge of LH. This may be due to the increased expression of GnRH receptors on the anterior pituitary.
When does a fertilized egg implant within the wall of the uterus?
6 days after fertilization
When is hCG first detectable in the blood? When can it be detected on a home pregnancy test?
hCG is detectable in the blood 1 week after conception.
It can be detected on a home pregnancy test 2 weeks after conception.
What are the benefits of breastfeeding to the mother?
--facilitates mother-child bonding
--decreases maternal risk of breast and ovarian cancer
What are the benefits of breastfeeding to the infant?
Breastmilk contains maternal immunoglobulins (IgA), macrophages and lymphocytes; It is associated with a decreased risk of infection. Consumption of breastmilk is also associated with a decreased risk of developing asthma, allergies, obesity and DM.
What vitamin needs to be supplemented for children who are exclusively breastfed?
Breastmilk is the ideal nutrition for infants of what age?
<6 months of age.
What is the average age of onset of menopause? What environmental risk factor is associated with earlier onset of menopause?
Average age of onset: 51
Risk factor for earlier onset: smoking
Why do we see a decrease in estrogen in menopause?
Estrogen is produced by the granulosa cells of the ovarian follicles. The age-related decline in the number of follicles leads to an age-related decline in estrogen.
What hormone changes do we see in menopause?
Decreased estrogen releases LH and FSH from feedback inhibition. We therefore see:
What are common symptoms of menopause?
Atrophy of the Vagina
Coronary artery disease
Is estrogen produced after menopause? What is its source? What are the side effects?
Yes. The source of estrogen production after menopause is the peripheral conversion of andorgens in adipocytes to estrone via aromatase.
The increase in androgens can lead to hirsutism.
What hormone change is specific for menopause?
greatly increased FSH levels
What is menopause typically preceded by?
4-5 years of abnormal menstrual cycles.