L3 - Male Repro Flashcards
1
Q
male accessory repro organs - internal organs
A
ducts for sperm storage and transport
- assoc glands: prostate, bulbourethral, seminal vesicles
2
Q
male external genitalia
A
penis
- scrotum
3
Q
location of prostate
A
encircles urethra
- cancerous/enlargement impedes urination
4
Q
urethra as a common passage
A
ventral aspect of penile shaft
- surrounded by corpus spongiosum.
- common passage for urine + semen.
5
Q
what is glans?
A
enlarged tip of penis
- foreskin (may be removed by circumcision)
6
Q
what is the penile erectile tissue?
A
corpus spongiosum around urethra
- corporus cavernosa = most density, spongy, fills with blood = erection
7
Q
what is scrotum?
A
extension of abdominal wall suspended outside abdomen.
- divided into two sacs.
8
Q
fetal development of testes
A
- in abdomen until 7th month, then descend.
- essential that they descend outside body cavity for normal sperm production.
- normal T is not descended, but core temp too high = abnormal development of sperm.
9
Q
vascularization of testes - what does it do?
A
allows for normal T production + secretion.
- facilitates heat-exchange mechanism
10
Q
how does vascularization help heat-exchange
A
spermatic cord ties testes to body.
- testicular nerve, vas deferens, testicular artery, testicular veins
cool blood supplies the testes, heat transfers from arterial branches to veinous drainage = cooler blood supplying testes.
11
Q
what is cryptorchidism?
A
testes failed to descend on their own.
12
Q
where does spermatogenesis take place?
A
seminiferous tubules
- outer fibrous capsule
13
Q
how sperm travels out ?
A
seminiferous tubules
- > rete testis (convergent area in testis)
- > efferent ductules
- > epididymis
- > vas deferens
14
Q
what is inguinal canal?
A
canal that testes descend thru to land in scrotum.
-spermatic cord passes thru inguinal canal
15
Q
what surrounds seminiferous tubules?
A
intersitial tissue = blood vessels + Leydig cells
16
Q
journey of sperm past vas deferens
A
- extends behind bladder + joins with seminal vesicles to form ejaculatory duct. prostate + bulbourethral add secretions too.
17
Q
what other secretions contribute to semen?
A
- prostate gland secretes fluid into urethra
- bulbourethral drain into urethra
18
Q
what does semen contain?
A
nutrients
- protective buffers
- seminal-vesicle derived chemicals
- Prostaglandins
- mucoid secretions
- water
- sperm
- zinc
19
Q
what kind of nutrients in semen?
A
fructose + other things to ensure viability of sperm cells
20
Q
what do the protective buffers do?
- source?
A
neutralize acidic vaginal secretions + residual urine in urethra.
- from prostate + bulbourethral glands
21
Q
function of seminal-vesicle derived chemicals
A
- promote increased sperm mobility
- unsure exactly what this is
22
Q
Prostaglandins (PG)
A
produced by seminal vesicle
(thought they came from prostate)
- unclear function but maybe assist in contraction of duct system + facilitate ejaculation
23
Q
what are mucoid secretions?
- fxn?
- source?
A
- lubrication of urethra.
- from bulbourethral glands.
24
Q
function of zinc in semen?
A
important micronutrient for humans
- isn’t clear what the function is, but low zinc assoc with infertility.
25
general function of secretions in semen?
protect male repro tract from pathogens, bacteria.
26
spermatogenesis - where?
seminiferous tubules
27
2 types of cells in seminiferous tubules?
- developing sperm
| - sertoli cells
28
layout of cells in seminiferous tubules
- basement membrane surrounds the tubule.
- sertoli cells make up wall of seminiferous tubule
- developing sperm inside, attached to sertoli cells.
- moving inwarrds = more mature sperm cells.
- centre = fluid filled lumen that collects mature cells
29
where is T produced?
Leydig cells - in interstitium. Sertoli cells depend on Leydig cells for T which supports Sertoli fxn
30
names of sperm at different maturation stages
@BIRTH:
primordial germ cell converts to spermatogonia -> stays quiescent until puberty.
@PUBERTY:
- spermatogonia goes thru mitosis - 1 cell moves on thru meiosis, the second continually divides thru mitosis
- spermatogonia -> 1-ary spermatocyte -- meiosis 1 --> secondary spermatocytes (diploid) --meiosis 2--> spermatids (haploid) --differentiation -> mature sperm
31
time for full maturation of sperm?
can take 64-74 days.
| - but 30 million spermies made per day.
32
why are sertoli cells called sustentacular cells?
reference to their fxn in supporting development of sperm cells.
33
what do Sertoli cells do for developing spermatogonia?
- in constant contact with sperm = provide nourishment, secrete inhibin, activin, growth factors, enzymes and androgen-binding protein.
34
what is androgen-binding protein
binds to androgens and takes them out of circulation.
35
sertoli cells as barrier
form unbroken ring around the outer circumference = sertoli-cell barrier (blood-testis barrier) tight junction to regulate what passes thru/protect from bacteria/pathogen
36
where are leydig cells found?
located in connective tissue spaces between tubules
37
what are function of Leydig cells?
| - active/quiescent when?
synthesize + release T. also convert T to estradiol which is important for spermatogenesis (aromatase)
active in fetus, quiescent from birth -> puberty. reactivate at puberty
38
hormone influence on production of sperm
Gn act on cells in testes.
FSH on Sertoli = increase sertoli fxn - increase spermatogenesis. also require T to function (LH has indirect function on spermatogenesis).
LH on Leydig cells = stimulate T production/secretion
39
```
function of Androgen-binding protein in production of sperm?
- produced where?
```
helps to concentrate T levels in seminiferous tubules
- allows continued Sertoli function
- produced in Sertoli cells.
40
function of inhibin on productin of mature sperm
- has negative feedback effect on ant.pit. to decrease FSH.
| - T also has negative feedback on LH at hypothal + ant.pit.
41
what does activin do?
acts on ant.pit to increase FSH release.
| - increase Gn = increase T + spermatogenesis
42
sperm cell morphology through the developmental processes
- cells bound to sertoli until transformation complete
| - final maturation in epididymis = lose cytoplasm + develop tail
43
normal sperm cell morphology
head
- mostly nucleus, contains all genetic info.
- acrosome = tip of nucleus.
midpiece: formed by mitochondria. provide energy for movement
tail: flagellum. propel at 1-4 mm/min.
44
what is acrosome?
protein-filled vesicle, contains enzymes that are necessary for fertilization
45
where is sperm stored? how is it stored?
vas deferens + epididymis.
- passive storage, no energy needed.
- increased pressure from sperm build up moves sperm along to seminiferous tubules + as far as epididymis
46
fluid:sperm content in storage
may decrease pressure by reabsorbing water/fluid.
| increase sperm concentration
47
propulsion of sperm during ejaculation?
peristaltic movement of vas deferens and ejaculation propel sperm
48
process of penile erection
1. rest: corpora cavernosa + corpora spongiosa - flaccid, not engorged with blood.
2. sexual excitation: imaginative, or irl - sexually relevant stimuli. dilates small arteries that supply erectile tissue = increase blood flow - engorged with blood
3. Prevent venous outflow. passive compression of veins to trap the blood in the erectile tissue = penile tumescence + engorgement of blood for erection
49
Neural input to penile arteries at rest
- at rest, dominant input to penile arteries is sympathetic = inhibits erection (NA)
50
stimulus for erection?
-CNS pathway triggered by sensation, spinal reflex in lower spinal cord
OR
PNS: input from penis mechanoceptors
51
how CNS/PNS input changes CNS output?
activate parasympathetic: non-adrenergic, non-cholingergic autonomic neurons
52
what do non-adrenergic + non-cholinergic autonomic neurons do?
```
release NO (vasorelaxation) and VIP, suppress/inhibit sympathetic activity
= dilation of arteries to increase arterial blood. compress venous drainage.
```
53
what happens if there's no sympathetic inhibition?
problems with vasodilation: issue with gaining/ maintaining erection for significant period of time.
54
what may occur if there's a spinal cord injury where input to the brain is impaired?
erection is still possible if spinal cord is still intact at lower sacral region. erectile reflex region intact.
- CNS won't have role, so psychogenic stimuli won't work
- spinal reflex/mechanical stimuli should work tho.
55
implications of CNS involvement in erection?
psychogenic input is important.
| (-) experience may suppress activation of PNS and prevent suppression of SNS
56
4 steps in male sexual response cycle?
| * duration?
1. excitement
2. plateau
3. orgasm
4. resolution
* duration of phase differs btw individuals/encounters*
57
what is the excitement phase?
AROUSAL
- changes from unstimulated, to partially stimulated to full erection.
- slight elevation of testes.
58
what is the plateau phase?
erection is maintained
- release of secretions from bulbourethral gland to lubricate urethra
- enlargement of prostate
- testes elevate
- increase diameter/size of testes + penis.
- darkened scrotum.
59
what is the orgasm phase?
= Emission + ejaculation
- releases of semen.
contract: seminal vesicle, bulbourethral, prostate.
- internal sphincter to bladder closes = no backwards movement.
- contractions in ductal systems and urethra due to symp activation + PG = ejaculation + release of semen.
60
what is the resolution phase?
erection disappears + symp tone increases, unstimulated state.
- de-tumescence : vasocontriction, venous drain allowed.
- testes descend, scrotum thins
* no re-arousal.
* duration varies*
61
what is ejaculation?
discharge of semen from penis
62
what mediates ejaculation?
spinal reflex mediated by afferent pathways from penile mechanoreceptors
63
what are the two phases of ejaculation?
emission
| ejaculation
64
what is the emission phase of ejaculation?
symp mediated.
- contract epididymis, vas deferens, ejaculatory ducts, prostate + seminal vesicle.
- empty sperm + secretions into urethra
65
what is ejaculation phase of ejaculation?
~3ml of semen expelled from urethra due to symp activation + hormones causing rapid contractions of smooth + skeletal muscles at base of penis.
- sphincter at base of bladder is contracted to prevent retrograde ejaculation
66
what is an orgasm?
muscular contractions, pleasure + systemic physiological changed.
- followed by latent period
- can have without ejaculation, or ejaculation without orgasm
67
hormonal control of testicular function
- no cyclical changes (except pulsatile release of GnRH)
- GnRH secretion every 90 mins.
FSH on SErtoli
LH on leydig = T
68
negative feedback by testicular hormones
- T inhibits LH: at ant.pit and hypothal to decrease GnRH
| - inhibin (produced due to FSH) decreases FSH secretion: secreted by Sertoli cells.
69
Testosterone in the prostate?
conversion to DHT by 5-a-reductase
- more potent
- male pattern baldness
- prostate enlargement
- other 2-ary sex characteristics
70
Testosterone in brain, liver, adipose tissue?
converted to estradiol by aromatase
- estradiol may support bone growth
