Male repro system

Question 1

what are the functions of the testis

Answer 1

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

Question 2

Briefly outline how testosterone is produced in testis

Answer 2

1. Leptin to kisspeptin
2. Kisspeptin to GnRH
3. GnRH to FSH and LH
4. FSH to Sertoli cells to spermatogenesis (and some steroidogenesis)
5. LH to Leydig cells to steroidogenesis

Question 3

Deeply outline how testosterone produced in testis

Answer 3

1. Leptin (found in fat) facilitates production kisspeptin
2. Kisspeptin in arcuate nucleus facilitates hypothalamus to release GnRH
3. GnRH stimulates pituitary to release FSH and LH
4. FSH to sertoli cells, spermatogenesis (some steroidogenesis)
5. LH to Leydig cells to steroidogenesis

Question 4

Outline the negative feedback cycle that follows testosterone production

Answer 4

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

Question 5

what is the basic function of the sertoli cells, what do they respond to

Answer 5

FSH to sertoli cells= spermatogenesis, some steroidogenesis, inhibin for negative feedback

Question 6

what is the basic function of Leydig cells, what do they respond to

Answer 6

LH to Leydig cells= steroidogenesis (testosterone)

Question 7

what do leydig cells convert into testosterone

Answer 7

cholesterol

Question 8

functions of testosterone

Answer 8

intra-testicular effects on sertoli cells
cell cooperation
on distant organs, 2ndry sex ch
feedback
DHT

Question 9

what is DHT and how is it produced

Answer 9

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

Question 10

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

Answer 10

facial and body hair
male pattern hair loss
prostate enlargement
differentiation of genitalia in fetal and early life

Question 11

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

Answer 11

libido
stimulating muscle and bone growth
voice deepening
sebum production and acne

Question 12

spermatogenesis vs spermiogenesis

Answer 12

spermatogenesis: production of sperm
spermiogenesis: final stage of spermatogenesis, maturation of spermatids into spermatozoa

Question 13

how long from spermatogonial stem cell to mature into spermatozoa

Answer 13

approx 70 days

Question 14

outline spermatogenesis

Answer 14

1. Primordial germ cell migrates along genital ridge
2. Mature into spermatogonia
3. Mitosis of spermatogonia- 1 cell repleneishes germ cell pool/ spermatogonia, 1 cell goes forwards to become sperm
4. growth to primary spermatocytes
5. meiosis 1 to secondary spermocytes
6. meiosis 2 to spermatids, haploid
7. spermiogenesis to spermatozoa

Question 15

order the names of stage of sperm we see through spermatogenesis

spermatids
primary spermatocytes
spermatogonia
spermatozoa
secondary spermatocytes
primordial germ cell

Answer 15

primordial germ cell
spermatogonia
primary spermocytes
secondary spermocytes
spermatids
spermatozoa

Question 16

at what point do the baby sperm go from diploid to haploid

Answer 16

after meiosis 2, so spermatids

Question 17

name the parts of a mature spermatozoa with a brief description

Answer 17

acrosome- digestive enzymes to penetrate oocyte

head- nucleus and dna

midpiece- mitochondria

tail- flagellum, propulsion at 1-3mm/ minute

Question 18

how do baby sperm mature through sertoli cell

Answer 18

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

Question 19

where does final part of sperm maturation happen and what do they gain

Answer 19

in epididymis, as a result of DHT, sperm gain mitochondria and flagellae, become motile

Question 20

why are sertoli cells called nurse cells, what functions

Answer 20

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)

Question 21

are the seminiferous tubules inside the sertoli cells or are the sertoli cells inside the tubules

Answer 21

seminiferous tubule contains sertoli cells

Question 22

what do the semineferous tubules do

Answer 22

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

Question 23

what is the blood testis barrier and why so important

Answer 23

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

Question 24

how are sperm motile

Answer 24

hydrolysis of ATP in mitochondria provides energy for motility, flagellum contains microtubules and dynein, an ATPase

sperm are immotile in seminiferous tubules

Question 25

what is the last step of sperm maturation and where does it occur

Answer 25

capacitation, in female tract

Question 26

what is the route of sperm from testis to fanny

Answer 26

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

Question 27

rough proportions of where ejaculate comes from

Answer 27

testis- 5%
seminal vesicles- 65%
prostate 30%
glands- 1%

Question 28

how many sperm per ejaculation

volume of normal ejaculation

Answer 28

200-500 million
2 to 5ml

ie 100 million sperm per ml

why so much? bc they basically all die lols

Question 29

oligospermia

Answer 29

low sperm count

Question 30

azoospermia

Answer 30

absence of sperm

Question 31

what happens when sperm inside female genital tract

Answer 31

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

Question 32

where does fertilisation occur

Answer 32

FALLOPIAN TUBE MOTHERFUCKER

Question 33

outline fertilisation motherfucker

Answer 33

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

Question 34

how does IVF work

Answer 34

intacytoplasmic sperm injection
suction holds egg in place
sperm injected with pipette, tail already broke, voila

Question 35

how is oestrogen produced in men

Answer 35

LH to Leydig cell to testosterone

FSH stimulates aromatase enzyme, testosterone is aromatised into oestrogen