Male reproductive system Flashcards
what bones make up pelvis
sacrum + ilium + ischium + pubis + coccyx
joints of pelvis
acetabulum (hip bone + femur), sacroiliac (sacrum + ilium) and pubic symphysis (pelvis + femur)
pelvic inlet
top of pelvic bone - open, always larger than outlet
pelvic outlet
bottom of pelvic bone, closed by muscles
subdivisions of pelvis
false/greater and true/lesser
features of false/greater pelvis
Superior region, Above pelvic inlet, Contains GI tract
features of true/lesser pelvis
Inferior region, Between inlet and outlet, Contains internal reproductive organs
female pelvis
Broader subpubic angle, Oval inlet, Straighter coccyx - facilitate childbirth
male pelvis
Narrower subpubic angle, Heart shaped inlet, Curved coccyx
pelvic floor muscles + openings
Two muscles: levator ani (ant.) and coccygeus (post.). Openings are urethra, anal canal and vagina (in females)
perineum
Region inferior to the pelvic floor and between upper region of the thighs. Contains external genitalia and anus
urogenital triangle
anterior, urethral/vaginal opening and external genitalia
anal triangle
posterior, anal canal and fat
male reproductive tract
Testes –> Epididymis –> Ductus (vas) deferens –> Ejaculatory duct –> Urethra
what does scrotum contain
2 testes; 2 spermatic cords; arteries and veins
function of testes
produce sperm, testosterone and inhibin
what surrounds testes
dense fibrous capsule called tunica albuginea which invaginates into testes to form seminiferous tubules in which sperm is produced
structure of seminiferous tubules
Testes have lobules containing seminiferous tubules. Tubules join to form rete testis. Join to form ductules leading to epididymis
cells in seminiferous tubules and what they produce
Leydig cells produce testosterone. Sertoli cells produce inhibin. Spermatogenic cells produce spermatozoa
blood-testis barrier
sertoli cells joined by tight junctions to form a lining around inside of seminiferous tubules
features of epididymis
Sperm enter from seminiferous tubules and exit via ductus deferens.
Site of sperm maturation. By the time sperm exits, sperm is fully capable of swimming and fertilising
Very long when unravelled (60m)
features of ductus deferens
In spermatic cord
Covered by smooth muscle - for ejaculation
Runs behind urinary bladder
Dilates to form ampulla
Storage site for sperm
structure of spermatic cord
One on each side
Runs between abdomen and testes
Contains:
- ductus deferens
- blood vessels - testicular arteries and veins
- nerves
- lymphatics
ejaculatory duct
Formed by the union of the duct from the seminal vesicle and the ampulla
Opens in the prostatic urethra
structure of male urethra
Epithelium changes: transitional, columnar, stratified squamous
3 sections: prostatic, membranous, penile/spongy urethra
2 sphincters:
- External: skeletal muscle, voluntary control of urination
- Internal: detrusor muscle
function of internal sphincter
Closes bladder thus ensures sperm ejaculated through the urethra
Retrograde ejaculation: sphincter doesn’t close, therefore sperm ends up in bladder
2 functions of penis
urination and copulation
two types of erectile tissue in penis
- 2 corpora cavernosa - main erectile tissue, dorsally located
- 1 corpus spongiosum - contains urethra, forms bulb and glans, ventrally located when erect
muscles in scrotum
Dartos lines scrotum and cremaster holds testes
function of dartos muscle
smooth muscle that contracts to wrinkle skin to make scrotum smaller so less SA for heat exchange, when its cold
function of cremaster muscle
come from inside and contract to draw testes up into body for heat conservation
structure of seminal vesicle
2 of them
Location = Posterior to bladder and lateral to ampulla or ductus deferens
Merges with ampulla to form ejac duct
function of seminal vesicle
Produce viscous secretion - 60% of semen, fructose to nourish sperm, alkaline pH to protect against acidic vagina
function of prostate gland
Produces secretion - 30% of semen; slightly acidic, milky fluid containing enzymes (PSA - prostate specific antigen); contains citrate to nourish sperm; contributes to sperm activation, viability and motility
location of bulbourethral glands
2 glands located in the urogenital diaphragm - part of pelvic floor
Ducts open into spongy/penile urethra
function of bulbourethral glands
Contribute 5% of semen volume
Secretions lubricate and wash out urinary acids in urethra prior to ejaculation
process of spermatogenesis
- During development, spermatogonia migrate from yolk sac to testes and remain dormant until puberty
- At puberty, spermatogonia divide by mitosis into type A and type B spermatogonia
- Type B spermatogonia differentiates into primary sex cell (primary spermatocyte - diploid), which undergoes meiosis I
- Forms secondary spermatocytes (haploid n)
- These undergo meiosis II to form spermatids (haploid)
- Spermatids differentiate into spermatozoa with a head, body and tail via spermiogenesis
- Spermatozoa released into lumen
- 1 type B spermatogonium forms 4 spermatozoa
spermiogenesis
maturation of Spermatid to spermatozoa
Develop tail
Nucleus condenses
Mitochondria contained in midpiece
Shed any unnecessary cytoplasm
Luteinising hormone
gonadotropin from ant. pit, stimulates Leydig cells to secrete testosterone. Testosterone gives negative feedback to ant. pit
follicle stimulating hormone
gonadotropin from ant. pit, controls spermatogenesis. Inhibited by inhibin
testosterone
from Leydig cells, it is an androgen - hormone which develops male characteristics (gonads into testes; spermatogenesis; aggression & libido)
GnRH
gonadotropin releasing hormone released from hypothalamus
