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physiology 2 > male reproductive biology > Flashcards

male reproductive biology Flashcards

1
Q

the bipotential gonad

A

has both wolffian and mullerian ducts

for males,
wolffian ducts differentiate epididymis, vas deferents
mullerian ducts regress (apoptosis)

for females ,
muller an ducts differentiate to oviducts, Fallopian tubes, uterus, cervix and upper vagina
wolffian ducts regress (apoptosis)

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2
Q

SRY controls

A

early testis differentiation
sertoli and leydig cells
sertoli cells secrete AMH - causes female reproductive structures to regress
leading cells secrete testosterone which induces differentiation of the wolffian duct system (epididymis, vas deference, sex accessory glands)

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3
Q

no-SRY gene

A

7-8 weeks - primitive gonad cortex develops not ovary (medullar regresses)
embryonic ovary does not secrete hormones

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4
Q

puberty is regulated by

A

HPG axis
adrenal cortex also secondarily involved

brain stimulates the hypothalamus to increase production of GnRH which stimulates anterior pituitary to increase LH and FSH to trigger gonads to produce sex hormones
ovaries produce oestrogen (oestradiol) and testes produce testosterone
FSH and LH also stimulate the development go oocytes and spermatozoa

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5
Q

hypothalamus in puberty

A

hypothalamus generates pulses of GnRH around 12th year of life

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6
Q

pulses of GnRH dependant on

A

pulses typically occur at night, due in part to gradual decrease in nocturnal melatonin secretion from pineal gland
also influences by nutritional status of body and growth rate
GH an IGF-1 stimulate reproductive function
leptin/ghrelin - metabolic hormones that determine size of fat stores

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7
Q

kisspeptin

A

patients with Kiss1 or KissR null mutations have hypogonadotrophic hypogonadism (HH) - pathological impubertism + infertility of CNS origin
a rise in the pulsatile release of kisspeptin in the median eminence takes place at puberty
exogenous administration of kisspeptins advances the onset of puberty and activates the pulsatile release of GnRH

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8
Q

testosterone is secreted by

A

leydig cells in response to LH

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9
Q

dehydrotestosterone

A

made from testosterone by 5a-reductase in some target cells
binds receptor stringer than testosterone
amplifies action of testosterone in some target tissues

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10
Q

systemic testosterone inhibits

A

GnRH and LH secretion

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11
Q

blood testes barrier

A

sertoli barrier

keeps testosterone in testes to prevent diffusion into blood and negative feedback

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12
Q

Sertoli cells secrete ABP

A

androgen binding protein

binds testosterone and keeps it at local high testosterone

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13
Q

testes

A

formed near kidneys - descend to scrotum

guided by gubernaculum through inguinal canal

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14
Q

undescended testes

A

crytorchidism - infertility

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15
Q

scrotum

A

sweat glands, pampiniform plexus, cremaster and darts muscles (increases in temperature causes cremaster and dartos to relax and the testes drop)

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16
Q

pampiniform plexus

A

warm blood comes down and looses heat to testicular blood rising back up

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17
Q

spermatogenesis

A

occurs in seminiferous tubules

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18
Q

epididymis

A

coiled tube which enlarges into vas deferens

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19
Q

vas deferens enters

A

prostate gland
content pass into ejaculatory duct and into the internal urethra
and urethra carries sperm away

20
Q

germ cells in seminiferous tubules

A

spermatogenia

mature, proliferate and differentiate into spermatozoa

21
Q

Sertoli cells

A

nourish and provide support for developing spermatozoa by providing local hormones, lipids and glycogen
create blood testis barrier

22
Q

myofibroblasts

A

contractile
when sperm are in the seminiferous tubules they can’t move yet - must be mechanically moves out before they acquire motility

23
Q

spermatogenesis

A

primordial germ cells migrate and become spermatogonia

24
Q

spermatogonia

A

at puberty, spermatogonia mature, proliferate and differentiate into 1° spermatocyte
meiosis 1 into 2 x 2° spermatocytes
meiosis 2 into 4 x spermatids
differentiate into mature spermatozoa

25
Q

1 spermatogonium

A

can make 512 sperm

26
Q

spermatozoa

A

contain haploid genome
acrosome - large quantities of hyaluronidase and proteolytic enzymes to facilitate ovum penetration
minimal cytoplasm
tails - mitochondria-packed so lots of power
motile microtubules flagellate

27
Q

epididymal sperm maturation

A

testicular spermatozoa are incapable of fertilising eggs (unless injected)
maturation achieved at distal corpus or cauda
acquire progressive motility
biochemical changes - increasing capacity for glycolysis, increase phospholipid FA content, activate CatSper (Ca trigger for acrosome reaction)

28
Q

seminal vesicles

A 
paired glands 
65% of seminal fluid 
alkaline 
prostaglandins, fibrinogen and fructose 
semenogelin (prevents early sperm capacitance, limits motility)
29
Q

semenogelin

A

gel slowing down the sperm so they can acquire motility without moving away

30
Q

prostate

A

30% of seminal fluid
liquefying enzymes, fibrinolysis
PSA - serine protease - hydrolyses semenogelin (sperm motility inhibitor)

31
Q

PSA

A

enzyme that gets rid of semenogelin

32
Q

bulbourethral glands

A 
paired glands 
5% seminal fluid 
alkaline 
pre ejaculatory fluid 
make movement of ssperm easier
33
Q

vasodilation in erection

A

increased arterial blood flow to corpora cavernosa

turgor compresses veins to limit loss of blood creating erection

34
Q

corpus spongiosum

A

remains pliable in erection - prevents urethral occlusion

35
Q

erection is controlled by

A

integrating centres (lumbar) activated by descending path (aroounsal) and afferents from genitalia
parasympathetic nerves in penis release
- ACh + VIP (co-transmitters) create vasodilation
- NANC fibres release nitric oxide for vasodilation

36
Q

erection is sympathetic or parasympathetic

A

parasympathetic

37
Q

emission

A

movement of semen through the urethra
vas deferens smooth muscle contraction move sperm forward
prostate, seminal vesicle smooth muscle contraction move prostatic and seminal fluid forward
mix in internal urethra (+ bulbourethral secretions)

38
Q

ejaculation

A

propulsion, expulsion

rhythmical contraction of bulbospongiosus (skeletal muscle)

39
Q

way finding of sperm

A

use chemotaxis (using sensing progesterone receptors) and thermotaxis (seek warmer environment)

40
Q

capacitation of sperm

A

PSA degrades semenogelin
increase in motility, alkaline uterine/fallopian fluid alters membrane (increase in calcium permeability and CatSpur channels)

41
Q

acrosome reaction

A

hyaluronidase and proteolytic enzymes digest proteins in ovum ECM
sperm reaches zona pellucida
sperm membrane binds receptor proteins, entire acrosome rapidly dissolves and releases enzymes
open penetrating pathway for the sperm to enter the ovum
sperm head and oocyte membranes fuse (cortical reaction) and deliver sperm genome

42
Q

sperm membrane binds

A

ZP3 proteins

43
Q

why does only 1 sperm enter the oocyte

A

sperm entry causes Ca2+ release which triggers cortical reaction

44
Q

cortical reaction

A

cortical granules exocytosed into the periviteline space

45
Q

cortical granules contain

A

proteases - that severe ZP3 receptors - any other bound sperms fall off and new sperm can’t bind
hyalin - forms a layer hardening the vitelline membrane making it impenetrable
hygroscopic mucopolysaccharides (GAGs) expand the vitelline space

physiology 2 (21 decks)

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