reproductive system Flashcards
the organs of the male reproductive system include:
· testes (gonads), which produce sperm & secrete hormones
· a system of ducts that receive, store, and transport sperm (epididymis, ductus deferens, ejaculatory ducts, urethra)
· accessory sex glands that provide secretions (seminal vesicles, prostate, bulbourethral glands)
· supporting structures (scrotum & penis)
what is the scrotal septum?
divides the scrotum into 2 sacs, each containing a single testis
what are the dartos and cremaster muscles?
· found in scrotum
· contraction of its muscle fibers regulate the temperature of the testes
· e.g. in response to cold temperatures, the cremaster & dartos muscles contract to move testes closer to body, where they can absorb body heat
normal sperm production requires what temperature?
about 2 to 3 degrees celsius BELOW body temperature
what is the function of seminiferous tubules? what kind of cells do they contain?
· tightly coiled tubules within the testes where sperm are produced
· contain 2 types of cells: spermatogenic cells that form sperm, and Sertoli cells which support sperm formation
list the layers of tissue around the scrotum and testes:
from superficial to deep: · skin of scrotum · dartos muscle · external spermatic fascia · internal spermatic fascia · tunica vaginalis (peritoneum) · tunica albuginea (of testis)
Sertoli cells (or sustencaular cells) are embedded among the spermatogenic cells in the seminiferous tubules. what is the function of Sertoli cells?
· form the blood-testis barrier, which isolates developing gametes from the blood
· nourish spermatocytes, spermatids, and sperm
· phagocytize excess spermatid cytoplasm as development proceeds
· control movements of spermatogenic cells & the release of sperm into the lumen of the seminiferous tubule
· produce fluid for sperm transport
· secrete the hormone inhibin
· regulate the effects of testosterone & FSH
in the spaces between adjacent seminiferous tubules are clusters of cells called Leydig (interstitial) cells. what is the function of Leydig cells?
secrete testosterone
describe the anatomy of a sperm:
major parts are head & tail:
· the flattened, pointed head contains a nucleus with 23 highly condensed chromosomes
· covering anterior 2/3 of nucleus is the acrosome, a cap-like vesicle filled with enzymes to help sperm penetrate the secondary oocyte
· tail is divided into 4 parts:
1. neck - contains centrioles
2. middle piece - contains mitochondria arranged in a spiral, which provide ATP/energy
3. principal piece - largest portion of the tail
4. end piece - terminal, tapering portion of tail
briefly describe hormonal control of testes:
· hypothalamus secretes GnRH, which stimulates anterior pituitary to secrete LH & FSH
· LH stimulates Leydig cells to secrete testosterone
· FSH acts indirectly to stimulate spermatogenesis
· FSH & testosterone act synergistically on Sertoli cells to stimulate secretion of androgen-binding protein (ABP), which binds to testosterone and keeps its concentration high
· testosterone stimulates the final steps of spermatogenesis
· Sertoli cells release inhibin
list the ducts that sperm pass through on its way out of the seminiferous tubules in the testes:
from seminiferous tubules to:
· straight tubules
· rete testes (a network of ducts)
· efferent ducts (coiled ducts in the epididymis)
· ductus epididymis (single tube that efferent ducts empty into)
describe the anatomy of the epididymis:
· a comma-shaped organ that lies along the posterior border of each testis
· consists mostly of tightly coiled ductus epididymis
· efferent ducts from the testis join the ductus epididymis at the larger, superior portion of the epididymis called the head
· the body is the narrow midportion
· the tail is the smaller, inferior portion
· at its distal end, the tail of the epididymis continues as the ductus (vas) deferens
what is the function of the epididymis?
· the site of sperm maturation (sperm acquire motility & ability to fertilize an ovum), which occurs over a period of about 14 days
· helps propel sperm into the ductus (vas) deferns during sexual arousal
· stores sperm, which remain viable here for up to several months
describe the anatomy of the ductus deferens (or vas deferens):
· a less convoluted continuation of the ductus epididymis
· ascends along the posterior border of the epididymis through the spermatic cord, and then enters the pelvic cavity where it loops over the ureter and passes over the side and down the posterior surface of the URB
· the dilated terminal portion of the ductus deferens is the ampulla
what is the function of the ductus deferens (or vas deferens)?
· conveys sperm during sexual arousal from the epididymis toward the urethra by peristaltic contractions
· can store sperm for several months
the spermatic cord is the supporting structure of the male reproductive system that ascends out of the scrotum. describe the anatomy of the spermatic cord:
· contains: the ductus (vas) deferens as it ascends through the scrotum, the testicular artery, veins that drain the testes and carry testosterone into circulation, autonomic nerves, lymphatic vessels, and the cremaster muscle
· the spermatic cord & ilioinguinal nerve pass through the inguinal canal
describe the anatomy of the ejaculatory ducts:
· each ejaculatory duct is 2cm long and is formed by the union of the duct from the seminal vesicle & the ampulla of the ductus (vas) deferens
· the ejaculatory ducts form just superior to the base (superior portion) of the prostate and pass inferiorly and anteriorly through the prostate
· they terminate in the prostatic urethra, where they eject semen & seminal vesicle secretes just before the release of semen from the urethra to the exterior
describe the anatomy of the male urethra:
· about 20cm long, the male urethra passes through the prostate, the deep muscles of the perineum, and the penis
· it is subdivided into 3 parts:
1. prostatic urethra, which passes through the prostate
2. membranous urethra, where it passes through deep muscles of perineum
3. spongy (penile) urethra, where it passes through the corpus spongiosum of the penis
· the spongy urethra ends at the external urethral orifice
what is the function of the male urethra?
· shared terminal duct of the reproductive & urinary systems
· passageway for both semen & urine
where are the seminal vesicles located?
the paired seminal vesicles are convoluted pouchlike structures lying posterior to the base of the urinary bladder & anterior to the rectum