Male repro system Flashcards
what are the functions of the testis
hormone production- mainly testosterone which acts within testis to facilitate spermatogenesis and is also carried to other organs
production of haploir male gametes for reproduction
Briefly outline how testosterone is produced in testis
- Leptin to kisspeptin
- Kisspeptin to GnRH
- GnRH to FSH and LH
- FSH to Sertoli cells to spermatogenesis (and some steroidogenesis)
- LH to Leydig cells to steroidogenesis
Deeply outline how testosterone produced in testis
- Leptin (found in fat) facilitates production kisspeptin
- Kisspeptin in arcuate nucleus facilitates hypothalamus to release GnRH
- GnRH stimulates pituitary to release FSH and LH
- FSH to sertoli cells, spermatogenesis (some steroidogenesis)
- LH to Leydig cells to steroidogenesis
Outline the negative feedback cycle that follows testosterone production
under influence FSH, sertoli cells produce inhibin, and Leydig cells under LH produce testosterone.
Inhibin and tstosterone inhibit secreteion of GnRH at hypothalamus and of LH and FSH at pituitary
results in equilibrium
what is the basic function of the sertoli cells, what do they respond to
FSH to sertoli cells= spermatogenesis, some steroidogenesis, inhibin for negative feedback
what is the basic function of Leydig cells, what do they respond to
LH to Leydig cells= steroidogenesis (testosterone)
what do leydig cells convert into testosterone
cholesterol
functions of testosterone
intra-testicular effects on sertoli cells cell cooperation on distant organs, 2ndry sex ch feedback DHT
what is DHT and how is it produced
DHT (dihydrotestosterone) is produced from testosterone via action of 5a reductase
converted within specific sites, eg the liver
very potent androgen, cannot be converted to oestrogen
which of these are driven by DHT
libido facial and body hair voice deepening sebum production/ acne male pattern hair loss differentiation of genitalia in fetal and early life stimulate muscle and bone growth prostate enlargement
facial and body hair
male pattern hair loss
prostate enlargement
differentiation of genitalia in fetal and early life
which of these are driven by testosterone
voice deepening male pattern hair loss stimulating muscle and bone growth prostate enlargement libido sebum production and acne facial and body hair differentiation genitalie fetal and early life
libido
stimulating muscle and bone growth
voice deepening
sebum production and acne
spermatogenesis vs spermiogenesis
spermatogenesis: production of sperm
spermiogenesis: final stage of spermatogenesis, maturation of spermatids into spermatozoa
how long from spermatogonial stem cell to mature into spermatozoa
approx 70 days
outline spermatogenesis
- Primordial germ cell migrates along genital ridge
- Mature into spermatogonia
- Mitosis of spermatogonia- 1 cell repleneishes germ cell pool/ spermatogonia, 1 cell goes forwards to become sperm
- growth to primary spermatocytes
- meiosis 1 to secondary spermocytes
- meiosis 2 to spermatids, haploid
- spermiogenesis to spermatozoa
order the names of stage of sperm we see through spermatogenesis
spermatids primary spermatocytes spermatogonia spermatozoa secondary spermatocytes primordial germ cell
primordial germ cell spermatogonia primary spermocytes secondary spermocytes spermatids spermatozoa
at what point do the baby sperm go from diploid to haploid
after meiosis 2, so spermatids
name the parts of a mature spermatozoa with a brief description
acrosome- digestive enzymes to penetrate oocyte
head- nucleus and dna
midpiece- mitochondria
tail- flagellum, propulsion at 1-3mm/ minute
how do baby sperm mature through sertoli cell
at base of sertoli cell are the spermatogonium, lie just above blood vessels
mature up through sertoli cell until become spermatids close to lumen, will then pass into lumen
where does final part of sperm maturation happen and what do they gain
in epididymis, as a result of DHT, sperm gain mitochondria and flagellae, become motile
why are sertoli cells called nurse cells, what functions
they nurse the baby sperm into strong big boy sperm
-produce lots protein that nourishes and supports
- sertoli cells phagocytose the residual cytoplasm lost by sperm as they develop
- blood testis barrier
(inhibin)
are the seminiferous tubules inside the sertoli cells or are the sertoli cells inside the tubules
seminiferous tubule contains sertoli cells
what do the semineferous tubules do
convert testosterone to DHT and oestradiol
secrete androgen binsing protein to increase testosterone levels inside the seminiferous tubules to stimulate spermatogenesis
secrete AMH, inhibins, activins
what is the blood testis barrier and why so important
one of tightest blood-tissue barriers, between the blood vessels and seminiferous tubules, produced by tight junctions btwn sertoli cells
prevents sperm antigens contact with systemic/ lymphatic systems as would cause immune response to sperm
regulates composition of luminal fluid in which germ cells grown and develop
how are sperm motile
hydrolysis of ATP in mitochondria provides energy for motility, flagellum contains microtubules and dynein, an ATPase
sperm are immotile in seminiferous tubules
what is the last step of sperm maturation and where does it occur
capacitation, in female tract
what is the route of sperm from testis to fanny
produced in testis
enter epididymis
pass through vas deferens (deferent duct) (which is inside spermatic cord)
through ampulla, seminal vesical secretions join
ejaculatory duct, prostatic secretions join
ejaculated through urethra
rough proportions of where ejaculate comes from
testis- 5%
seminal vesicles- 65%
prostate 30%
glands- 1%
how many sperm per ejaculation
volume of normal ejaculation
200-500 million
2 to 5ml
ie 100 million sperm per ml
why so much? bc they basically all die lols
oligospermia
low sperm count
azoospermia
absence of sperm
what happens when sperm inside female genital tract
sperm deposited at neck of cervix
sperm cooperate, form channels in the cervical mucus by swimming together as easier
sperm conc falls rapidly as ascend-
200 million in vagina
20 million after cervix
2000 in fallopian tubes
where does fertilisation occur
FALLOPIAN TUBE MOTHERFUCKER
outline fertilisation motherfucker
sperm meets egg. love at first sight.
acrosome activates and vesiculates, digests outer layer and zona pellucida, sperm enters
sperm digests and moves through zona pellucida
sperm-egg biomembrane fusion, prevents more sperm
sperm nucleus enters cytoplasm
how does IVF work
intacytoplasmic sperm injection
suction holds egg in place
sperm injected with pipette, tail already broke, voila
how is oestrogen produced in men
LH to Leydig cell to testosterone
FSH stimulates aromatase enzyme, testosterone is aromatised into oestrogen
