Male phys pt 1

What male reproductive structure is responsible for the production of gametes (spermatogenesis)

testes

what is the major secretory product of the testes?

testosterone

what is the network of veins found in the male spermatic cord?

papiniform plexus

what is the function of the pampiniform plexus?

acts as a heat exchanger, cooling the blood in adjacent arteries (this keeps the temp where the sperm like it)

what is the process in which spermatozoa are produced from male primordial germ cells?

spermatogenesis

spermiogenesis is ______ and involves ____

maturation of spermatids to mature spermatozoa → involves no cell division

what divides the spermatogonia into spermatocytes?

mitosis

what reduces the diploid spermatocytes into haploid spermatids

meiosis

what is the maturation of spermatids into mature spermatozoa?

spermiogenesis

for the HPG axis, explain the players

hypothalamus → secretes GnRH

anterior pituitary → responds to the GnRH and produces LH and FSH

LH acts on Leydig cells → so they produce testosterone (androgens)

FSH acts on sertoli cells

what does inhibin do? what secretes it?

secreted from sertoli cells; goes to inhibit the anterior pituitary gland from making more FSH and LH

continuous exposure to GnRH or intermittent administration of high doses of GnRH analogs causes ____

a decrease in the number of GnRH receptors (desensitization)

the GnRH receptors are ____. explain briefly

G protein-coupled receptor → IP3 and DAG → Ca release and PKC activation

pulsatile secretion does not _____

desensitize the gonadotrope to GnRH (no decrease in GnRHR numbers)

at a frequency of 1 pulse per hour, GnRH from hypothalamus preferentially increases ____

LH secretion

at a frequency of 1 pulse every 3 hours, GnRH from hypothalamus preferentially increases ____

FSH secretion (3 hours, 3 letters)

When GnRH acts on the anterior pituitary gland ____ or ___ is secreted, how do we determine which one is secreted?

LH or FSH → 1 pulse per hour is LH, 1 pulse per 3 hours is FSH

____ inhibits the pulse frequency

GABA

_____ stimulates the pulse frequency

Kisspeptin neurons and glutamate neurons

what is the principle target for LH

Leydig cells

LH acts on ___ cells and FSH acts on ____ cells

LH: Leydig (L goes with L)

FSH: sertoli cells

Leydig cells have ____ receptors not ____ receptors

have LH not FSH receptors

LH receptor on Leydig cells being activated goes down what pathway?

Galpha-s → adenylyl cyclase → cAMP → protein kinase A

FSH receptor on sertoli cells being activated goes down what pathway?

Galpha-s → adenylyl cyclase → cAMP → protein kinase A

Sertoli cells secrete what?

anti-mullerian hormone and androgen-binding protein (ABP) and estradiol and inhibin

what has negative feedback on the HPA axis to inhibit FSH secretion?

inhibin (secreted by sertoli cells)

sertoli cells have ____ not ___ receptors

have FSH not LH receptors

Normal circulating levels of testosterone does what?

inhibits the pulsatile release of GnRH (negative feedback)

inhibin has negative feedback at the level of ___ not ____

level of anterior pituitary not hypothalamus

what is the precursor to androgens?

cholesterol

androstenediol → testosterone happens by what enzyme?

3beta-hydroxysteroid dehydrogenase

what androgen? functions to differentiation of the epididymis, vas deferens, seminal vesicles, and genitalia

testosterone

what androgen? required for the masculinization of the external genitalia in utero

DHT

What androgen? growth and activity of the prostate gland

DHT

which is more potent DHT or testosterone?

DHT

what is the precursor for testosterone?

androstenedione

explain the conversion of androstenedione to testosterone

done by 3beta-hydroxysteroid dehydrogenase; can go backwards or forwards to make either one

interaction between the androgen-AR complex and nuclear chrpmatin increases what?

DNA transcription