Lecture 8 - Male Reproductive System Flashcards
what are 3 general functions of the reproductive systems ?
gamete production
facilitate fertilization
sustained development of embryo and fetus
what are 4 main structures of the reproductive systems?
gonads
ducts
accessory glands
support structures
what are the 4 ducts of the male reproductive system?
epididymis
ductus (vas) deferens
ejaculatory ducts
urethra
what are the 3 accessory sex glands?
seminal vesicles
prostate gland
bulbourethral glands
what are the 2 support structures?
penis
scrotum
what is the function of the testes?
produce gametes (sperm) and secrete sexual hormones
what are the 3 functions of the duct system?
transport and store sperm
assist in sperm maturation
convey sperm to exterior
what is the function of the sex glands?
provide secretion to compose semen
what is the function of the penis?
delivery of sperm (and annoy me)
what does the scrotum do?
contains and supports (temp regulation) testes
what separates the testis?
scrotal septum
what muscle plays a part in composing the scrotum?
dartos muscle
what does the scrotum do in response to cold temperatures?
dartos muscles contracts = scrotum skin tightening and wrinkling
cremaster muscle contracts = testes moved closer to pelvis
what muscle is the cremaster muscle an extension of?
internal obliques
what organ do the testes originate near?
kidneys
how much does one testis weigh in an adult?
10-15 gr
where do the testes develop and than migrate to, before birth?
inside abdominal cavity or embryo and fetus - migrate into scrotum before birth
what is the gubernaculum?
a fibrous cord connecting the fetal gonads to the scrotum (or labia majora)
what hormone influences the descent of the gonads, guided by the gubernaculum?
anti-mullerian hormone (AMH)
what canal do the testis push through to exit the abdominal cavity via progressive shortening of the gubernaculum?
inguinal canal
at what month does the descent of the testis in the fetus finish?
end of the 7th month of fetal life
what is cryptorchidism? and what can cause it?
a condition in which the testes do not descend into the scrotum - caused by a deficit in anti-mullerian hormone (AMH)
what is the ‘tunica albuginea’ and what is it made of?
a white fibrous capsule surrounding the testis (covers surface) composed of dense irregular connective tissue
where is the tunica albuginea located?
internal to the tunica vaginalis
the tunica albuginea invaginate insides the testis to form what?
a series of internal compartments called lobules
what are 3 coverings of the testis that are formed by structures in its way, as it descends through the inguinal canal?
external spermatic fascia internal spermatic fascia tunica vaginalis (serous membrane derived from peritoneum)
what are the covering layers of the testis from deep to superficial?
tunica albuginea of testis tunica vaginalis (peritoneum) internal spermatic fascia external spermatic fascia
what does the tunica vaginalis secrete?
serous fluid
what is ‘hydrocele’?
abnormal collection of serous fluid between the two layers of the tunica vaginalis
in the descend of the testis, what muscle do some of the fibres of the internal obliques form?
cremaster muscle
the cremaster muscle is part of the ______ cord in males and is fully functional.
spermatic
in females, the cremaster muscle is only a few fibers that adhere to the _______
round ligament of the uterus
how many lobules does the testis contrain?
200-300
what does each lobule of the testis contain?
a single seminiferous tubule
where are sperm generated? and by what process?
generated in the seminiferous tubule, by spermatogenesis
what 2 types of cells are contained in the seminiferous tubules?
spermatogenic cells (spermatogonia, dormant until puberty) sustentacular cells/sertoli cells
what cell supports spermatogenesis occurring in the seminiferous tubules?
Sertoli cells
spermatogenesis generates spermatozoa, which. are developed from_____
spermatogonia
define ‘spermatogonia’
diploid cells that via successive mitosis and meiosis make spematozoa
what is the order of sperm cells from start to end of spermatogenesis in seminiferous tubules, starting with spermatogonium?
spermatogonium (2n -stem cells) primary spermatocytes (2n) secondary spermatocytes (n) spermatid (n) sperm cells/spermatozoon (n)
what is considered the final stage of spermatogenesis?
spermiogeneis - the maturation of spermatids into sperm (no cell division occurs)
what does the spermatid do during spermiogenesis?
each spermatid breaks the cytoplasmic bridge and becomes a round, single haploid cells
where does spermiogenesis occur?
withint Sertoli cells
what are the two metamorphic changes spermatids go through during spermiogenesis?
- elongation of cell
2. cytoplasmic re-arrangement to discard “excessive baggage” (organelle and cytosol)
what stage are sperm shaped by the sertoli cells and then enter the lumen of seminiferous tubule?
spermiogenesis (sperm still cant move at this stage)
what 4 physical features appear in the spermatids during spermiogenesis?
spermatids elongate
acrosome forms atop nucleus
flagellum develop
mitochondria develop
where are spermatids located by the end of spermiogenesis?
close to lumen of seminiferous tubule, just hanging from epithelium
spermatid transform into what, at the end of spermiogenesis?
spermatozoa - immobile
what is spermiation?
when spermatozoa are released into lumen of seminiferous tubule
what happens to sperm after 14 days in the epididymis?
sperm finalize maturation and acquire ability to move
what are the two portions of the sperm?
head
tail
what is contained in the head of the sperm?
nucleus with 23 chromosomes and acrosome filled with enzymes (hyaluronidase and proteases)
what are the components that make up the tail of the sperm?
neck (centrioles)
middle piece (mitochondria)
principal piece (longest)
end piece
what are 4 external factors that can interfere with spermatogenesis?
malnutrition
alcoholism
cadmium salts
some drugs
what product attacks spermatids?
cottonseed oil
what 2 external factors can diminish spermatogenesis?
x-ray radiation
temps 37 degrees or higher
at puberty, the hypothalamus increases secretion of what hormone?
gonadotropin-releasing hormone (GnRH)
what does GnRH do?
stimulates they hypophysis (ANTERIOR pituitary) to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
what does LH do?
stimulates interstitial cells (Leydig’s cells) in the testis to secrete testosterone
what is testosterone converted into?
dihydrotestosterone (DHT)
what does testosterone inhibit?
secretion of LH by negative feedback
FSH and testosterone act on the Sertoli cells to accomplish what?
the sertoli cells secrete androgen-binding protein (ABP)
what does the binding of ABP with testosterone result in?
keeps testosterone concentration high to stimulate last steps of spermatogenesis
what do Sertoli cells secrete once achieved level of spermatogenesis occur?
inhibin to inhibit secretion of FSH
what are the two androgen hormones?
testosterone
DHT
when the androgen homones bind together on the same receptor what 3 effects do they produce?
- development of male sexual characteristics (puberty)
- development of sexual behaviour
- stimulation of anabolism (protein synthesis)
what are the secondary male characteristics?
MSK growth male hair patterns increase oil gland secretion enlarged larynx (no direct role in reproductive function)
what are the 4 main ducts of the male reproductive system?
epididymis
vas deferens
ejaculatory ducts
urethra
sperm and fluid from the seminiferous tubules flow in order through which 4 ducts of the testis?
straight tubules
rete testis (network of tubules)
efferent ducts
ductus epididymis
what is the epididymis?
coma-shaped organ lying along the posterior border of the testis - consists of very coiled ductus epididymis (20 ft)
where does the efferent duct from the testis join the ductus epididymis?
at the larger, superior portion of the epididymis called the “head”
what part of the epididymis are the body and tail located?
body = narrow mid portion tail= distal end and continues as the ductus (vas) deferens
how long may viable sperm be stored in the epididymis for?
several months (non ejaculated sperm are reabsorbed)
what is the ductus (vas) deferens?
uncoiled end of the ductus epididymis with an increased diameter
the ductus deferens ascends along the posterior border of the epididymis through the _____ and enters into the _____ after passing through the _______
spermatic cord,
pelvic cavity,
inguinal canal
what structure does the ductus deferens loop over?
the ureters and down posterior of the bladder
what is the dilated, terminal portion of the ductus deferens called?
ampulla of the vas deferens (conveys sperm towards urethra and can store viable ones for several months)
what are ejaculatory ducts formed by?
the union of the end portion of the ampulla of the vas deferens and the duct of the seminal vesicle
what structure does the ejaculatory ducts pass through?
prostate gland (terminate in prostatic urethra)
what does the ejaculatory ducts do?
ejects sperm and secretion of the seminal vesicles just before ejaculation
