Gonads Flashcards
What are the female Gonads and their Hormones?
Ovaries
- Estrogens (predominantly estradiol) – steroid hormones
- High concentration of aromatase – catalyzes conversion of androgens to estrogen
estradiol = estrogen
What are the male Gonads and their Hormones?
Testes
- Androgens (primarily testosterone) – steroid hormones
- High concentration of enzymes that convert androstenedione to testosterone
Are testosterone and estrogen exclusive to males or females?
Testosterone and estrogen are not unique to males and females, however, the ratio between the two differs
both derived from cholesterol, in presence of aromatase, androstenedione becomes estrogen. Without aromatase, androstenedione becomes testosterone
(higher level of aromatase in the ovaries)
What are the functions of the Male Gonads and Sex Hormones?
Testes: produce testosterone (steroid hormone) and sperm (gametogenesis – spermatogenesis)
Where does Spermatogenesis take place?
Spermatogenesis in the seminiferous tubules
Where is Testosterone secreted from?
Testosterone secreted from Leydig cells
(found around the seminiferous tubules)
What are the 2 primary Androgens?
- Testosterone
- Majority is synthesized in the testes
- Dehydroepiandrosterone (DHEA) and androstenedione
- Synthesized in the adrenal cortex
- Much less potent than testosterone
What are the effects of testosterone in males?
How does testosterone convert?
Testosterone Transformation in Target Tissues
Adult prostate and tissues with 5-⍺-reductase: conversion to
dihydrotestosterone (DHT) (a more potent version of testosterone)
Brain: conversion to estradiol by aromatase
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make into cards
Hypothalamus secretes GnRH
acts on anterior pituatiry to release FSH and LH
FSH and LH enter testes and act on Sertoli Cells and Leydig Cells
Sertoli cells is responsible for paracrine factors in spermatogenesis
inhbin stops FSH secretion -> negative feedback loop
testosterone stops LH secretion and GnRH secretion - Negative fb loop
What is the purpose of Anabolic Steroid Use?
- Use of synthetic androgens to improve increase muscle hypertrophy, sport performance etc.
- Negative effects include but are not limited to overstimulation of the prostate gland, aggression and development of breast tissue
Why is taking testosterone bad?
two symptoms ->
when exogeneous testosterone is increased, endogenous testosterone decreases, resulting in reduced testicular size and sperm count
What is the function of Gonads and Sex Hormones in the Females?
Ovaries: produce ova (gametogenesis), estrogen and progesterone (steroid hormones)
- Maturation of female gamete (ovum) is cyclical (unlike male gamete which is continuous)
- Average menstrual cycle is 28 days
ova = egg
Differentiate b/w the 3 hormones of estrogen
Maturation of Ova
What are Oocytes?
Oocytes, also known as ova or egg cells, are the female reproductive cells produced by the ovaries. They are the largest cells in the human body and are essential for sexual reproduction in females.
surrounded by granulosa cells
What are Granulosa Cells?
secrete estrogen, and just before ovulation, small amounts of progesterone and inhibin
They surround and support the developing oocyte (egg cell) within the follicle and play essential roles in follicle development, ovulation, and hormone production.
What is Theca?
granulosa cells that have proliferated and differentiated during follicle maturation. Also produces estrogen
What are Preantral and early antral follicles?
Preantral and early antral follicles are always present in the ovaries between puberty and menopause (they require FSH to further develop)
- At the start of menstrual cycle 10-25 of these already present preantral and early antral follicles begin to develop into larger follicles
one becomes dominant nad the rest of them die,
only one fully matures
What is atresia?
- ~1 week into the cycle, a dominant follicle continues to develop, and the others undergo atresia (cell death)
- Just before ovulation, the dominant follicle becomes so large that it balloons on the surface of the ovary
When does ovulation occur?
What is the corpus luteum?
Ovulation occurs when the walls of the follicle and ovary rupture (due to enzymatic digestion) and the oocyte is carried out
Once the follicle discharges the oocyte, the granulosa cells enlarge to become the corpus luteum which secretes large amounts of estrogen, progesterone and inhibin
Follicular Phase
Day 1 -14
Estrogen from granulosa cells of follicle
Progosterone synthesized and screted in very samll amounts by theca and granulosa (just before ovulation)
Luteal Phase
Day 14 - 28
Corpus Luteum primarily secrete and sythesize estrogen and progesterone
Order of Events
What hypophysiotropic hormone stimulates the anterior pituatiry to release FSH and LH? What glands do they act on? What actions do they cause?
GnRH stimulates anterior pituitary
FSH and LH act on testes and ovaries
Releases Testosterone and Estrogen/Progesterone
Testosterone -> Spermatogeneis
Estrogen/Progosterone -> stimulates changes in Ovaries
