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part I > physiology- male > Flashcards

physiology- male Flashcards

1
Q

what % of men is affected by infertility in UK?

impaired spermatogenesis affects what % of them?

A

6%

90%

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2
Q

what % of conceptions is affected by abnormal meiosis & meiosis?

what % of livebirths are affected by above?

A

7%

0.7&

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3
Q

what is the function of testes?

A

produce & store sperm

produce hormones

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4
Q

how much below body temp is the optimum temperature for production of sperm?

A

1.5-2.C

overheating of testes reduces sperm count

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5
Q

normal size and volume of testes?

A

3.5-5.5 cm long
2.0-3.0cm wide

15-30mL = volume

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6
Q

male reproductive tract structure:

A

ASPC

ampulla
seminal vesicle
prostate
Cowper’s gland

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7
Q

testes structure:

which part of testis is the site of spermatogenesis?

what % of testes is this?

how does it all fit

A

seminiferous tubules

90% of testes = seminiferous tubules

  • tubules are tightly coiled to create large surface areas = lobules
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8
Q

what do seminiferous tubes’ lobules feed into?

what does this structure lead into?

A

rete –>epidydimis & vas deferens

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9
Q

what are the walls of the seminferous tubule made of?

what kind of cells are these?

A

Sertoli cells

tall columnar endothelial cells

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10
Q

what cells lie on the basement membrane between Sertoli cells?

what are spaces between the cells filled with?

A

spermatogonia (primary germ cells)

  • blood
  • lymphatic vessles
  • Leydig cells
  • intersitial fluid - v high volume, would be considered oedemic in any other tissue
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11
Q

what layer is there in addition to basal lamina to protect from infection?

A

tight junction

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12
Q

role of tight junction (where exactly is this??)

A
  • opens to allow passage of spermatogonia prior to completion of meiosis
  • provides luminal and adluminal compartment
  • protects spermatogonia from immune attach
  • allows specific enclosed environment for spermatogenesis which is filled with secretions from Sertoli cells
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13
Q

spermatogenesis stages:
(names of cell)

A
  1. spermatogonia = sperm cell on basement membrane.
    capable of meiotic and mitotic divisision
    i.e. produces primary spermatocytes ot more spematogonia
  2. spermatocyte
    - committed to differentiative pathway
    primary spermatocyte = 46XY
    secondary spermatocytes have divided meiotically to 23X + 23Y
  3. spermatid
    - 2nd division occurs to give 4 round spermatids
  4. spermatozoa
    = mature sperm extruded into lumen
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14
Q

what controls movement of sperm cells into lumen?

A

Sertoli cell secretion

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15
Q

how long does sperm development take?

how frequent is a new wave?

A

74 days

every 16 days

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16
Q

oogonia vs spermatogonia
i. laid down as foetus
ii. fate of each germ cell
iii. supply finite/ infinite

A

i. both
ii. A begin meiosis to make oocyte
B begin meiosis to make spermatocyte or divide mititically to make more spermatogonia
iii. finite supply oogonia, infinite supply spermatogonia

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17
Q

hypotholamic/ pituitary/ gonadal axis in male

A

-ve feedback only

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18
Q

Leydig cell

i. which receptors are present?

ii. what is converted to what?

A

i. LH receptors (and oestrogen receptors)

ii. cholesterol –> androgens

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19
Q

LH stimulates Leydig cells to produce testosterone via what?

A

cAMP

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20
Q

in foetus testosterone production by Leydig cells is under control of which hormone?

A

hCG

21
Q

where within testes do androgens produced in Leydig cells go?

what is their role?

A

cross over to Sertoli cells

control of spermatogenesis (by stimulating Sertoli cell function)

22
Q

what can happen to testosterone released into circulation? (2)

A
  1. –> estrone and estradiol in skin and adipose tissue
    by aromatase
  2. reduced –> more active dihydrotesterone in peripheral target tissues
    by 5-alpha-reductase
23
Q

Sertoli cells

i. receptors present
ii. reaction which occurs
iii. which protein do Sertoli cells produce to concentrate testosterone?

A

i. FSH receptors (and androgen receptors)

ii. androgens –> oestrogen
(by aromatase)
androgens –> DHT

iii. androgen-binding protein

24
Q

2 hormones needed for spermatoigenesis

A

FSH, testosterone

other roles of testosterone:
- maintenance of prostate, seminal vesicles, ampulla and bulbourethral gland

25
Q

female equivilent of:
i. Leydig cells
ii. Sertoli cells

A

i. theca cells
ii. granulosa cells

26
Q

where does most E2 (oestradiol)come from:

i. prepuberty
ii. in adult

A

i. Sertoli cells
ii. Leydig cells

both are needed to initiate spermatogenesis

LH alone may be sufficient to re-initiate

27
Q

testosterone levels in testes vs in plasma?

A

in testes 100x those in plasma

28
Q

what hormone alone may be used to re-initiate spermatogenesis in hypotrophic hypogonadism in adult?

A

LH

29
Q

effect of exogenous steroids on -ve feedback:

A
  • testes shrink
  • hypotrophic hypogonadism (i.e. -ve feedback to hypothalamus is overwhelmed???)
30
Q

spermatozoan structure

3 main parts:

A
  1. head
    - acrosomal cap
    - postacrosomal region
  2. middle piece
    - microtubules = machinery of motility
    - mitochondira = energy of motility
  3. tail
    - principle piece
    - end piece
31
Q

where do mature spermatoza collect & pass onto?

A

rete, pass onto epididymis

32
Q

length of epididymis?

how long does it take sperm to pass?

3 parts of epididymus?

A

5m

8-14 days

caput (head) = start of maturation
corpus (body) = completion of maturation.. mobility
cauda (tail) = main site of storage

individual ducts of epididymis join to make vas deferens

33
Q

what causes erection?

which nervous system is involved?

A

vasodilation of the corpus cavernosum

autonomic - causes co-ordinated contractions of vas deferens and glands

34
Q

afferent/ efferent nerves involved in erection:

A

afferent: internal pudendal nerves

three efferent outflows: the parasympathetic pelvic nerve (stimulatory)
the sympathetic hypogastric nerve (inhibitory and some stimulatory
fibres)
somatic pudendal nerve (stimulatory)

35
Q

in erection/ ejaculation what is the role of:

i. sympathetic control
ii. parasympathetic control

A

i. sympathetic:
- movement of sperm into epididymus, vas deferens, penile urethra

ii. parasympathetic control
- erection and evacuation of urethra

36
Q

seminal fluid
consists of secretions from which 3 glands?

+ which other fluid

A

seminal vesicles
prostate
bulbo-urethral gland

+epididymal fluid

37
Q

ejaculate fluid reference values:
i. volume
ii. concentration
iii. progressive motility (i.e. % which must be forwards moving)
iv. normal forms (i.e. appear normal under microscope)

A

i. volume 1.5mL
ii. concentration 15million/mL
iii. progressive motility 32%
iv. normal forms 4%

38
Q

how is entry of semen into urethra prevented?

A

contraction of urethral sphincter

39
Q

getting to vagina:

A
  1. seminal fluid coagultes in vagina
    - prevents loss, later requalifies
    - seminal fluid changes acidic pH to alkali (from 3-4 to 7.2)
  2. sperm passes into cervix (mucous changes)
    - glycoproptein molecules arrange in parallel lines (aggregates)
    - micelles vibrate and aid passage of motile sperm
    - non-alginates sperm form reservoir in cervical crypts
40
Q

name of 2 changes sperm undergo when passing into uterus/ coming in contact with uterine fluid:

A
  1. capacitation
  2. acrosome reaction
41
Q

what happens during capacitation?

why?

what initiates capacitation

A

biochemical removal of the surface glycoprotein - this initiates whiplash movement of tail - sperm become more hyperactive

helps to reach and penetrate egg

uterine/ uterine tube fluid

42
Q

what is the purpose of the acrosome reaction?

A

allows sperm to male slit in zona pellucida (outer layer of egg) after binding to it

43
Q

what cell layer protects the egg?

what do these cells secrete?

A

cumulus cells

mucus matrix

44
Q

what causes zona pellucida secretions to withdraw?

A

LH surge

at this point 1st meiotic division resumes and completes

extra chromosomes are packaged into 1st polar body

45
Q

by which process is the sperm taken into the ovum?

what causes migration of cortical granules in egg to zona pellucida?

A

phagocytosis

cortical granules migrate to edge and fuse with zone pellucida

calcium eaves arising from fusion

46
Q

what happens as soon as 1st sperm enters ovum?

what is this process called?

A

membrane fusion

intravelline processing

47
Q

what happens once the sperm and egg have fused?

A

male sperm –> male pronucleus

female 2nd polar body (remember meiosis 2 happens one sperm enters egg I think –> female pronucleus

2 join, mitosis

48
Q

what is the blastocyst called once it reaches the 8-16 cell stage?

what are the 2 distinct cell types called by this stage?

A

morula

outer = trophoblast (develop into chorion/ placenta)
inner = cell mass

49
Q

what does blastocyst secrete to prevent breakdown of corpus luteum?

A

hCG

interacts with LH receptors on corpus luteum

part I (12 decks)

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