HRR: male repro II Flashcards
Describe testosterone production in utero
It spikes around the 6th month, as it is needed up until then for male internal and external genitalia differentiation. After that, it falls.
Describe testosterone after birth
There is a small spike between birth and one year of age, but it regresses within this time and Leydig cells become quiescent until puberty.
What initially stimulates Leydig cells in utero?
hCG secreted by the placenta.
When does LH begin to stimulate the fetal pituitary?
Week 10.
What are androgenic effects?
Effects relating to growth of male reproductive tract or development of secondary sex characteristics.
Androgenic effects are driven by…
Testosterone and DHT.
Anabolic effects are driven by…
Estradiol.
What would happen in men with aromatase gene deficiency?
Tall stature, persistent linear growth, delayed bone age. Aromatase deficiency means less estrogen. Without the estrogen, growth plates don’t fuse, and bones don’t strengthen.
What is needed to close growth plates?
Estradiol.
What does testosterone do to RBCs?
Stimulates erythropoietin and increases hematocrit.
Why do androgens promote lower voice?
They thicken the vocal cords, resulting in lower pitch.
What causes the penis to have rigidity?
Corporus cavernosa filling with blood and remaining constricted by tunica albuginea.
What is the primary neurotransmitter mediating penile smooth muscle relaxation and erection?
NO.
How does NO get into cells?
It just diffuses! Its lipophilic.
Describe NO erectile cellular mechanism.
- NO diffuses into cavernosal smooth muscle cell 2. cGMP is activated, activating PKG 3. PKG disrupts calcium inflow, lowering contraction 4. Relaxed muscle allows more blood to flow, causing an erection.
What breaks down cGMP?
PDE5.
What do PDE5 inhibitors do?
Keep more cGMP in the cavernosal smooth muscle cells, allowing for more muscle relaxation and resulting erection.
What is considered precocious puberty in boys?
Less than 9.
Describe appearance and bones in precocious puberty.
Shorter height, earlier voice change, earlier male genital development, advanced bone age.
Describe appearance and bones in late puberty.
Small testes, may be taller with poor muscle mass, pubic and facial hair preadolescent.
How does androgen abuse impact the appearance of the testes?
They’ll be soft and small.
What happens to sperm production in androgen abuse?
It drops! It is an inverse relationship- more exogenous testosterone, less spermatogenesis.
Would giving LH or FSH improve spermatogenesis in androgen abuse?
Nope.
What is androgen insensitivity syndrome?
An issue with AR receptors. Testosterone may be high, there may be infertility or female/ambiguous characteristics, and testes may be intraabdominal since testosterone and DHT can’t function properly.
