male reproductive physiology

Question 1

why do the testicles lie outside of the body

Answer 1

the temperature required for sperm production is lower than that of the body (1-2 degrees lower than the abdominal cavity in the scrotum)

Question 2

path of sperms following production

Answer 2

produced in the testes
pass through the epididymis
travel through the vas deferens to the seminal vesicles
secretions from the prostate gland and seminal vesicles are added to the sperm
exit the body through the urethra

Question 3

what is the role of the epididymis

Answer 3

storage site for sperm

sperm stay there for ~3mths while they mature

Question 4

structure of the testes

Answer 4

divided into several lobules
seminiferous tubules are within the lobules
testes are surrounded by a fibrous capsule

Question 5

what is the name for the fibrous capsule covering the testis

Answer 5

tunica albuginea

penetrates into the structure of the testis and divides it into several lobules

Question 6

what is the site of sperm production

Answer 6

seminiferous tubules in the testis

Question 7

where do the sperm travel after they have been produced in the seminiferous tubules

Answer 7

rete testis

this is where all the outflow of the seminiferous tubules merge and lead into the head of the epididymis

Question 8

what are the 3 parts of the epididymis

Answer 8

head
body
tail

Question 9

where does the vas deferens emerge

Answer 9

tail of the epididymis

Question 10

what are the 3 types of cells within the seminiferous tubule and what are their functions

Answer 10

germ cells - produce sperm
sertoli/sustentacular cells - support sperm producing cells, produce inhibin
interstitial (Leydig) cells - surround the seminiferouos tubules and produce testosterone

Question 11

what are the 2 main functions of the testis

Answer 11

sperm production - avg time from production to ejaculation = 64 days
testosterone production - male 2y sexual characters, controls spermatogenesis

Question 12

endocrine control of testicular function

Answer 12

reproductive hormones
GnRH from hypothalamus
gonadotropins - FSH and LH from ant pituitary
testosterone from testicles

Question 13

interaction of hormones on testes

Answer 13

hypothalamus releases GnRH
acts on ant pituitary to release FSH + LH
FSH - Sertoli cells facilitate Spermatogenesis
LH - Leydig cells, +ve feedback on spermatogenesis
sertoli cells release inhibin - -ve feedback on ant pituitary
Leydig cells produce testosterone - -ve feedback on ant pituitary and hypothalamus

Question 14

define spermatogenesis

Answer 14

sperm production from the priomordial germ cells in the seminiferous tubules

Question 15

length of avg cycle of spermatogenesis

Answer 15

64 days
germ cells pass through different developmental stages
mature sperm cells are produces

Question 16

what are the 2 distinct phases in spermatogenesis

Answer 16

spermatocytogenesis

spermiogenesis

Question 17

what is spermatocytogenesis

Answer 17

clonal expansion and maturation through mitotic and meiotic processes

Question 18

what is spermiogenesis

Answer 18

differentiation into mature sperm cells

Question 19

when does spermatogenesis begin

Answer 19

starts at puberty

continues lifelong

Question 20

steps of spermatocytogenesis

Answer 20

CLONAL EXPANSION
spermatogonia A
mitosis 
spermatogonia B 
MATURATION
spermatocyte I 
meiosis I
spermatocyte II
meiosis II
spermatid 
DIFFERENTIATION
spermatid 
sperm

Question 21

chromosomal division during spermatogenesis

Answer 21

mitosis - spermatogonium –> 1y spermatocyte, duplication, diploid chromosomes (46)
meiosis 1 - 1y spermatocyte —> 2y, 2 cells w/ haploid chromosome number
meiosis 2 - 2y spermatocyte –> spermatid, 2 cells w/ haploid chromosome
spermiogenesis - maturation of spermatids into functional sperm cells

Question 22

what factors affect spermatogenesis

Answer 22

medical
lifestyle
combination

can ultimately affect male fertility

Question 23

medical factors affecting spermatogenesis

Answer 23

pretesticular - problem with the hormonal control

testicular - problem at the site of production

Question 24

pretesticular medical factors affecting spermatogenesis

Answer 24

functional - XS weight loss/gain, stress
intracranial tumours, cysts, bleed
prolactinoma 
medications - opiates, external testosterone, steroid (body building)
genetic - Kallmann's syndrome

Question 25

testicular medical factors affecting spermatogenesis

Answer 25

``` surgery - orchidectomy, orchidopexy STI mumps orchitis testicular trauma or torsion radio/chemotherapy genetic - Klinefelter's (46 XXY), Y chromosome microdeletion, CF ```

Question 26

lifestyle factors affecting spermatogenesis

Answer 26

effect from mother during pregnancy - irreversible effects from father's sperm - reversible smoking - heavily impacts production and functional capacity of sperm obesity occupational and environmental chemical exposure

Question 27

steps to reduce the impact of factors affecting fertility (5)

Answer 27

improve lifestyle - normal BMI, stop smoking, alcohol in recommended limits healthy diet, exercise, adjustments to occupational exposure optimise underlying medical condition stop medications/switch to alternative pregnancy compatible medications reduce STI risk and treat promptly fertility preservation - sperm freezing prior to surgery or cancer treatment

Question 28

define oligospermia

Answer 28

low sperm count

Question 29

past fertility - things that could affect sperm count

Answer 29

puberty - delayed previous children/fertility personal/FHx of genetic problems previous fertility treatment

Question 30

things that could affect sperm count - androgen deficiency symptoms

Answer 30

infrequent shaving unable to grow beard low libido erection/ejaculation difficulty

Question 31

things that could affect sperm count - medical problems current/past

Answer 31

systemic disease malignancy prolactinoma

Question 32

things that could affect sperm count - genitourinary hx

Answer 32

``` STI mumps orchitis testicular trauma/torsion undescended testis recurrent UTI ```

Question 33

things that could affect sperm count - past surgery

Answer 33

inguinal hernia repair orchidopexy orchidectomy

Question 34

things that could affect sperm count - medications

Answer 34

high dose steroid testosterone replacement supplements: body building products - exogenous steroids

Question 35

things that could affect sperm count - occupation

Answer 35

exposure to chemicals, heavy metals, radiation

Question 36

things that could affect sperm count - lifestyle

Answer 36

``` sedentary food habits smoking obesity alcohol recreational drug use ```

Question 37

examination/investigations for low sperm count

Answer 37

``` BMI genital examination USS testis hormonal profile genetic test ```

Question 38

why is it important to palpate the vas deferens

Answer 38

may discover absent vas deferens which is a feature of CF

Question 39

genital examination for low sperm count

Answer 39

external genitalia, testicular size, palpation of vas deferens, inguinal hernia, varicocele

Question 40

hormonal profile for low sperm count

Answer 40

FSH LH testosterone prolactin

Question 41

genetic test for low sperm count

Answer 41

karyotype | Y chromosome microdeletion

Question 42

hypogonadotropic hypogonadism in men

Answer 42

low FSH, LH, prolactin, testosterone | hypothalamus or pituitary cause

Question 43

prolactinoma and fertility

Answer 43

high prolatcin | low sperm count

Question 44

hypergonadotropic hypogonadism in men

Answer 44

high FSH, LH low testosterone testicular cause

Question 45

things to look for in US of testes

Answer 45

testicular volume hydrocele varicocele cancer