✓ 1- Hormonal Regulation of Gonadal Function Flashcards
What are the functions of Estrogens?
- ↑ Libido
- Stimulation of growth of: uterus, fallopian tubes & vagina; mammary gland ductile system; follicles; bone & closure of epiphyses
- Secretion of plentiful, thin cervical mucus
- Stimulation of Granulosa cell-LH receptor formation
- Delay of bone loss at menopause
- Stimulation of thin sebaceous gland secretions
- Secondary sexual characteristics
- Sexual differentiation of brain
- ↑ progesterone receptors
What are the functions of Progesterones?
- Production of Secretory endometrium
- Stimulation of secretion of scant, viscous cervical mucus
- Stimulation of mammary lobular-alveolar growth
- ↑ Body temperature
- ↓ Uterine motility
What ovarian hormone opposes the action of Inhibit ?
Activin
What releases relaxin?
Corpus Luteum
What is the function of Relaxin?
helps soften cervix and relax pelvic ligaments at birth
What is the most potent form of estrogen?
17ß -estradiol
What is the predominant estrogen in postmenopausal woman?
Estrone
What is form of estrogen is produced mostly during pregnancy?
Estriol
What produces 17ß -estradiol?
Granulosa and Luteal cells [primarily]
What produces Estriol?
Produced by ovaries mostly during pregnancy
What produces Estrone?
Produced by ovary and peripherally
List the different form of Estrogens from most potent to least potent
- 17ß-estradiol
- Estriol
- Estrone
What two progestins are ovarian hormones?
- Progesterone
- 17 -hydroxyprogesterone
What androgens are ovarian hormones?
- Dehydroepiandrosterone (DHEA) & androstenedione ( →estrone →estradiol)
- Testosterone ( → estradiol) and dihydrotestosterone
How long is the luteal phase?
14 days
What cells are stimulated by LH in females?
Thecal cells
What cells are stimulated by FSH in females?
Granulosa cells
What cell produces inhibin in females?
Granulosa cell
What hormones are produced by Granulosa cells?
- Inhibin
- Estrogens
- Progestins
What hormones are produced by Thecal cells?
- Estrogens
- Androgens
What is the role of Inhibin in the Hypothalamic-Pituitary-Ovarian axis?
Inhibits the synthesis and release of FSH in pituitary gland
Where is sperm produced?
seminiferous tubules
Where are sperms stored and matured?
In epididymis
When do sperm become motile?
After spending 18-24 hours in the epididymis
Where are sperm stored?
- Epididymis
- Vas deferens
- Ampulla of Vas deferens
What is the function of the bulbourethral gland?
secretes a mucous fluid that lubricates, cleanses and buffers the urethra prior to emission and ejaculation
What is the function of 5-a-reductase Type 1 in skin?
Sebaceous gland activity and acne
What is the function of 5-a-reductase Type 2?
- External genitalia
- Prostate gland
- Growth of penis
- Darkening of Scrotum
- ↑Pubic hair and Axillary hair
- ↑ muscle mass
What is the function of Testosterone?
- Bone Growth
- ↑ RBC
- Muscle anabolic
- Sertoli function
- Wolffian duct to internal genitalia
- Erectile Function
- Libido
- ↑ VLDL, LDL
- ↓HDL
T/F: Sertoli cells are responsible for the production of Androgens
False, Leydig cells produce androgens, which is then used by Sertoli cells
What hormones are produced from the Leydig cell?
Androgens
What are produced from the Sertoli cell?
- Androgen-binding proteins
- Estrogens
- Inhibin
Where does spermatogenesis occur?
Sertoli cells
What cell produced inhibin in men?
Sertoli cells
What cells produces inhibin in men and females?
Men: Sertoli cells
Female: Granulosa cell
What cells are stimulated by FSH in males?
Sertoli cells
What cells are stimulated by LH in males?
Leydig cells
What hormone has a negative feedback on the anterior pituitary gland and hypothalamus in males?
Androgens
What structures produce testosterone?
Testes [95%]
Adrenal cortex [5%]
What is the primary source of estrogen and DHT in males?
Adipose tissue peripherally
Describe the Two cell theory hypothesis of Testicular Steroidogenesis
LH stimulates Leydig cells to produce testosterone from cholestrol. This testosterone either ends up in circulation or goes to the Sertoli cell where its aromatized to estrogen or converted to DHT. It can also bind to ABG to concentrate its levels
What hormone starts steriodogenesis?
LH
What is the estimated life span of sperm in female genital tract?
24-72 hours
What does the seminal vesicle contribute to semen?
- Gives it its mucoid appearance
- Provides fructose + coagulum
What is the function of semenogelins?
Keeps the semen in a coagulated form, until it reaches the female genital tract to keep it intact, then changes occur by anticoagulant from the prostate gland .
What does the prostate contribute to semen?
- Gives it its milky appearance
- Alkaline secretion
- Anticoagulum
Describe the activity of Sperm at different pH levels
- Active in a neutral to slightly alkaline media
- Loses their activity in acidic media
What does the vas deferens contribute to semen?
Sperm [10%]
What is the function of semen?
Prevents early capacitation and provides nutritions for sperm
Define Infertility in males
- counts <20 million/ml
- <50% motile sperm
- <60% normally conformed [shape etc.] sperm
How many sperm cells are produced daily?
120 million
How many days does it take spermatogenesis to complete?
70 days
What is the average sperm count?
60-100 million per ml
When does spermatogenesis start?
~13 years
What stimulates spermatogenesis?
LH and FSH
What is the function of nursing cells in spermiogenesis?
Sertoli cells:
- Provide nutrients [iron, transferring and lactate]
- Phagocytic action [removes excess cytoplasm shed by spermatozoa during spermiogenesis]
Define capacitation
changes that lead to hyperactivity of the sperm cells, which later allow them to go through the acrosome reaction.
What are the steps of capacitation?
removal of cholesterol + non-covalently bound epididymal /seminal glycoproteins → ↑Ca2+ permeability → influx of Ca2+ → ↑ intracellular cAMP levels → ↑ motiltiy
What two things achieved in capacitation is necessary for acrosomal reaction to occur?
- Hyperpolarization of the sperm plasma membrane
- and changes in ion permeability
What happens during acrosomal reaction?
cell membrane of the sperm cell fuses with the outer membrane of the acrosome → acrosomal content released outwards
What are the stage of Follicular growth and Ovulation?
Non-hormone dependent stage:
Primordial follicle → Primary follicle
- entry of a follicle into the early growth pahse is mainly dependent on intraovarian paracrine factors produced by oocyte and follicle cells
FSH dependent stage:
- Primary follicle → secondary follicle [w/ thecal and granulosa cell] → Tertiary follicle [w/ antrum] → Graafian follicle
LH dependent stage:
- Graafian follicle which matures and was bulging on ovary will burst and release the ovum → complete 1st meiotic division
- Remaining granulosa and thecal cells → corpus luteum → Corpus Albicans [if no pregnancy]
What hormones surge during ovulation?
Estrogen and LH
When does progesterone peak?
During the secretory phase
When does inhibin peak?
During the secretory phase
Describe the effect of Estrogen on Gonadotrophic Hormone levels
Initially estrogen has a negative feedback on FSH and LH, but when estrogen peaks, that’ll remove the feedback inhibition and we see a surge in LH and FSH
Which Gonadotrophic Hormone is higher during the follicular phase and luteal phase?
Follicular: FSH
Luteal: LH
What hormone stimulates the corpus luteum?
LH
What hormones does the corpus luteum produce?
Estrogen
Progesterone
Inhibin
Describe Gonadotrophic and Ovarian hormones relation to Corpus Luteum
LH is needed to stimulate corpus luteum, which then produces progesterone, this then has a negative feedback on LH, which causes the corpus luteum to regress to corpus albicans
What is the difference between thecal cells and Luteal cells?
TC do not express high levels of 17 -HSD, thus its major product is androstendione not testosterone
Describe the Two cell theory hypothesis of Ovarian Steroidogenesis
