Male Reproductive Physiology Flashcards
How do fat cells play a role with estrogen?
They contain aromotase which converts testoerone to estradiol
What are all of the substrates involved in steroid synthesis?
Cholesterol, pregenolone, progesterone, 17-OH-progesterone, Androstendione, testosterone, estradiol or dihydrotestosterone
Do males typically have estrogen in circulation?
Yes
What hormone stimulates androgen production?(2 points)
LH and FSH
What type of receptor does LH bind to stimulate steroid synthesis? What is the specific reaction that initiates of the steroids?
It binds a G-protein linked receptor. It stimulates the conversion of ATP to cAMP via the action of adenylate cyclase. This in turn activates a kinase.
How does the body maintain a high concentration of testosterone within the seminiferous tubules?
The sertoli cells produce androgen binding protein which maintains a high level of testosterone within the seminiferous tubules
When do the development of the seminferous tubules take place during development?(2 points)
6 and 7 weeks gestation
When does histologic differentiation of the feta ovary apparent during development?
6 moths gestation
How many days does it take the precursors of spermatogenesis to be realeased into the seminiferous tubules?
74 days
What secondary messenger is utilized by GnRH when it stimulates the release of LH?
GnRH binds to a cell surface receptor which increases the concentration of intracellular calcium
Where do you get a peak of testosterone in males?(4 points)
A peak at 5 months gestation, a peak of at birth, a peak at puberty and another constant peak at adulthood
Where are all of the substrates for steroid synthesis produced?(3 points)
Adrenal and Testes produce pregenolone, progesterone, 17-OH-progesterone, androgenstendione. Testis produce testosterone. Peripheral tissues produce estradiol and dihydrotestosterone.
LH stimulates what cell? This cell is stimulated to perform what type of activity?
LH stimulates Leydig cells to produce androgens, mainly testosterone
The androgens produced by the Leydig cells affect what target tissues and/or pathways?(2-3 points)
spermatogenesis, other target tissues and aromatization
What is the rate-limiting step for steroid synthesis?
The action of Star: bringing cholesterol into the mitochondria
How long does it take for spermatids/spermatozoa to pass through epididymis?( week range)
2-3 weeks
If the sertoli cells were affected by heavy metal poisoning, what would be the hormone profile?(3 points)
Normal LH, normal testosterone but increase FSH
How are the hormones GnRH and LH released in the body?
They’re released in pulses
What type of relative concentration of testosterone is required for spermatogenesis?
A very high local concentration
What is the average sperm count per mL?
50-150 million per mL
What is the fat of testosterone?
90% of it is secreted. 0.5-3.0 % is unbound and it interacts with peripheral tissue. The bound part is bound to albumin and SHBG.
What hormone regulates the secretion of LSH and FH?
gonadotropin releasing hormone
What temperature is required for spermatogenesis?
requires a temperature below core body temperature
What hormone is the major regulator of spermatogenesis and steroidogenesis? What hormone is the major regulator of this hormone? What type of hormone is this hormone?
Pituitary LH; GnRH; GnRH is a peptide hormone
How do the spermatogonia move during division and differentiation to form spermatozoa?
They move up closer and closer to the tubule of the seminiferous tubules
What number of sperm would lead to infertile by coitus?
Less than 4 million per mL
What is the volume of the average ejaculate?
3.5 mL
Why does the histologic differentiation of the fetal ovary take place at such a late time during development?
The granulosa cells haven’t organized around the dividing occytes to form the primary ovarian follicle
Sexual dimorphism of the gonads begin at that time during development(2 points)
6 and 7 weeks gestation
FSH stimulates what cell in the reproductive system? This cells is stimulated to perform what type of activity(4-7 points)
Sertoli cell; aromotase, growth factors for Leydig cels, growth factors for spermatogenesis, androgen binding protein and activin
What number of sperm in semen would lead to decrease fertility?
Less than 20 million total per mL
What are all of the cells involved in spermatogenesis?(7 points)
Dark Type A, Pale Type A, Primary Spermatocyte, Secondary Spermatocyte, Spermatids and Spermatozoa
What are causes of primary hypogonadism?(2-6points)
x-radiation, chemtherapy, chromosomal abnormalities, infection(mumps, orthitis), trauma, drugs(spirnolactone, ketoconazole, alcohol)
What are causes of secondary hypogonadism?(2-6 points)
Pituitary adenomas, benign tumors & cysts, metastases infiltrative disease, sarcoidosis, idiopathic congenital panhypopituitarism, Kallman Syndrome
A well-developed male is found to have small testes, increased semen volume, and azoospermia. What is your differential diagnosis?
anabolic steroid use
The evaluation of a male infertility patient shows that his testes were housed in the scrotum but were unusually firm to the touch and warm. His laboratory result indicates that he is azoospermic even though semen volume and serum testosterone concentration are within normal ranges. What do you think this patient’s problem is?
varicocele
A couple is evaluated for infertility. The problem appears to be with the male. Examination reveals a normal testosterone and LH, but an initial semen analysis reveals a decreased semen volume and no detectable sperm. Past history reveals surgery to repair an inguinal surgery, so a fine needle biopsy is done of the right testis. The fine needle biopsy demonstrates normal sperm morphology and normal sperm motility. The most likely cause of the patient’s infertility is
disordered sperm transport
In a 35-year-old father of two, who has smoked 4 packs of cigarettes a week since age 16, a failure of testosterone administration to lower LH and FSH levels might indicate:
a bronchogenic tumor secreting GnRH like peptide, but pulsatile
