Reproductive Physiology of the Male Flashcards

1
Q

what enzyme converts testosterone into estradiol

A

aromatase

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2
Q

what enzyme converts testosterone into DHT

A

5𝛼-reductase

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3
Q

what is de la chapelle syndrome

A

XXsry+
male internal and external genitalia but infertile due to lack of Eif2s3y gene

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4
Q

what does masculinization of the sexually dimorphic nucleus require

A

estradiol (E2)
testosterone produced in the testes converted to E2 via aromatase

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5
Q

what protects E2 from the female from entering the brain in the fetus

A

𝛼fetoprotein

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6
Q

3 parts of the male brain and what they are regulated by

A
  1. Libido - estradiol E2 (can be testosterone converting to E2)
  2. male behaviors (aggression, scent marking) - testosterone
  3. pulse generator - kisspeptin producing neurons w/ Testosterone, E2 and P4
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7
Q

explain the HPT axis

A

kisspeptin
GnRH
LH –> leydig cells, T production
FSH –> sertoli cells, inhibin, androgen binding protein and acts on sperm cells supporting mitosis/meiosis

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8
Q

days for spermatogenesis

A

60 days

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9
Q

days for epididymis travel

A

10-14 days

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10
Q

how do anabolic steroids affect reproductive function

A

5-10x T levels needed to maintain spermatogenesis
anabolic steroids only have 2-3x T = no spermatogenesis

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11
Q

what produces melatonin
precursor for melatonin
function of melatonin

A

pineal gland in absence of light
tryptophan
acts on pulse generator cells to regulate GnRH

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12
Q

how do animals regulate seasonal breeding?

A

melatonin

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13
Q

long day breeders (horse, wolf, fox, rodents, birds)

A

melatonin (-) kisspeptin
decreases GnRH

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14
Q

short day breeds (cattle, elk/deer, sheep)

A

melatonin (+) kisspeptin
increases GnRH

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15
Q

how does melatonin differ between males and females

A

males less affected - most species produce sperm year round

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16
Q

describe the effects on sperm with short term heat vs long term heat

A

short term heat - sperm abnormalities during spermatogenesis
long term heat - spermatogenesis ceases (e.g. cryptorchid)

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17
Q

Four Mechanisms of Thermoregulation

A
  1. arterioles/venous blood close to surface of skin of scrotum for dissipation
  2. sweat glands in skin of scrotum for evaporation
  3. pampiniform plexus (countercurrent exchange)
  4. tunica dartos & external cremaster muscle - contract/relax of scrotum and testes respectively
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18
Q

how does illness, stress and fat affect reproduction

A

illness - fever - elevated temp - negative effect on spermatogenesis
stress - cortisol - decreases kisspeptin - decreases T
fat - difficult thermoregulation in scrotum

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19
Q

at what temperature can spermatogenesis occur

A

temperatures 2-5 degrees
lower than body temp

20
Q

describe cryptorchidism

A

no spermatogenesis
leydig cells functional - T produced
increased incidence of seminoma
heritable or environmental

21
Q

describe spermatocytogenesis

A

occurs in basal compartment
spermatogonia > primary spermatocytes

22
Q

describe meiosis I

A

primary spermatocyte > secondary spermatocyte

23
Q

describe meiosis II

A

secondary spermatocyte > spermatid

24
Q

describe spermiogenesis

A

occurs in adluminal compartment
no cell division
spermatids (round then elongated) > spermatozoa

25
Q

what is critical for spermiogenesis? why?

A

Testosterone
because cells cannot make mRNA = no proteins
need sertoli cells to make enzymes and proteins via androgen binding protein maintain testosterone levels so cells can mature and progress

26
Q

function of the blood testis barrier

A

protects developing sperm from immune system attack

27
Q

what is unique about the stages in seminiferous tubules

A

see different stage in each seminiferous tubules on cross section - allows release of sperm everyday

28
Q

what determines the shape and size of sperm heads in different species

A

proamines

29
Q

what structure of the sperm head is responsible for penetrating/digesting the zona pellucida of the oocyte

A

acrosome

30
Q

where are the centrioles located

A

neck region of sperm

31
Q

what part of the sperm contains the mitochondria

A

midpiece

32
Q

what is the cytoplasmic droplet

A

cytoplasms migrates down tail as sperm matures through the epididymis and is lost when sperm becomes motile

33
Q

what occurs if the cytoplasmic droplet remains

A

problem in spermiogenesis or epididymal maturation → decreased fertility

34
Q

what is the order of sperm transport to the epididymis

A

sertoli cell > seminiferous tubule > rete testis > efferent ducts > head of epididymis

35
Q

what is the only part of the male reproductive tract that has cilia

A

efferent ducts

36
Q

head of epididymis
muscle?
epithelium? villi?
fertility?
motility?

A

thin smooth muscle
more epithelium, long microvilli (bc majority of fluid is absorbed)
not fertile
not motile

37
Q

body of epididymis
muscle?
fertility?
motility?

A

thin smooth muscle
not fertile
not motile

38
Q

tail of epididymis
muscle?
epithelium? villi?
fertility?
motility?

A

large amount smooth muscle
less epithelium , short microvilli
fertile
not motile

39
Q

when does sperm become motile

A

when mixed with seminal plasma due to water, proteins, sugars, salts, citrate/bicarb, gel

40
Q

erection is parasympathetic or sympathetic

A

parasympathetic

41
Q

ejaculation is parasympathetic or sympathetic

A

sympathetic

42
Q

what 2 structures of the female require sperm motility

A

cervix
utero-tubule junction

NOT the uterus bc sperm moves via uterine contraction

43
Q

what is capacitation and where does it occur

A

oviductal epithelium

loss of cholesterol, increase in IC calcium, loss of seminal plasma proteins coating the cell exposing receptor for zona pellucida

44
Q

what induce the acrosomal reaction

A

zone pellucida proteins

45
Q

what is the acrosomal reaction

A

release of acrosomal enzymes (ZP1, ZP2, ZP3) to expose receptor for oolemma so sperm (sumo 1) can bind to oolemma fusing sperm and oocyte membranes

46
Q

methods of semen collection

A

artificial vagina “gold standard”
electroejaculation
chemical ejaculation
manual stimulation

47
Q
A