Male Gonad Physiology Flashcards Preview

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Flashcards in Male Gonad Physiology Deck (64):
1

___ stimulates leydig cells in testes to make testosterone.

LH

2

HPG (T) axis

hypothalmic gnrh --> anterior pituitary lh, fsh --> testosterone and inhibin in testes

3

___ stimulates sertoli cells in testes to promote sperm development

FSH

4

___ forms inhibin in testes which is a mode of negative feedback

FSH

5

____ feedsback at the pituitary from the testes

inhibin

6

____ feedsback at the pituitary and hypothalamus from the testes

testosterone

7

____ syndrome results from low production of gnrh in parvi-cellular hypothalamic neurons due to failure of cell precursors to migrate to the hypothalamus

kallman's

8

GnRH is secreted into the ____ portal.

hypothalamo-hypophyseal

9

T/F GnRH levels in serum are too low for detection

T

10

Target of GnRH

gonadotrope cells in anterior pituitary

11

Circadian output of GnRH is regulated by _____ which results in highest levels of GnRH when?

melatonin --> peak in morning (highest level of LH and testosterone as well)

12

T/F stress and other similar changes may inhibit gonadtropin release

T

13

Higher frequency pulsatile gnrh release favors ___ secretion

LH

14

Excessively frequent pulsation/pathologic or continuous GnRH initially increases LH and FSH in a ____ effect but leads to GnRH receptor downregulation with resulting low LH/FSH. This can be mimicked by treatment with a GnRH agonist like ____

flare effect --> downregulation --> leuprolide

15

The process by which GnRH binding sites increase during troughs of GnRH pulses is called______

self priming

16

GnRH analog like leuprolide results in high/low LH

low

17

T/F LH and FSH are stored in separate granules

T

18

LH is metabolized by the ___

liver

19

LH/FSH has a longer serum half life.

FSH = 2 hours vs 20 mins

20

___ residues on FSH inhibit its metabolism

sialic acid

21

negative feedback on FSH is mediated by ____

inhibin b

22

negative feedback on lh is mediated by ____

testosterone

23

in early fetal development _____ controls development of testes and wolffian ducts

placental hcg

24

in late fetal development ____ controls testes development as fetal HPG axis matures

pituitary lh

25

In infancy, the hypothalamus is very sensitive to ___ negative feedback.

steroid

26

At what point in time do nocturnal FSH/LH pulses begin?

puberty

27

Testosterone synthesis

LH --> receptor --> STAR protein transports cholesterol from mitochondria into lumen of cell --> side chain cleavage to form pregnenolone --> either to progesterone or to androstenedione to testosterone

28

______ is the rate limiting step of steroid synthesis

transport of cholesterol out of mitochondria into cell lumen by steroidogenic acute regulatory protein (STAR)

29

_______ creates a hydroxyl group at the 17 carbon and cleaves the sidechain in steroid production

17 hydroxylase

30

The final step of steroid production involves ____ which removes a keto group to form testosterone.

17beta dehydrogenase

31

___ converts pregnenolone to progesterone

3beta dehydrogenase

32

T/F most testosterone is free in circulation.

F --> mostly bound to albumin or SHBG but 2% free for receptors

33

_____ binds androgen receptor with greater affinity than testosterone

DHT

34

What is the location of the androgen receptor?

nucleus

35

androgens dislodge ____ from the androgen receptor during binding

hsp90

36

___ is needed to stimulate sertoli cell function but ___ is the main regulator of spermatogenesis

fsh and testosterone

37

testosterone enters sertoli cells bound to ____

androgen binding protein

38

4 ways sertoli cells support spermatogenesis

create specialized microenvironment, expose germ cells to high levels of testosterone, coordinate maturation via gap junctions, and transport of differentiating germ cells toward lumen

39

____ occurs when anti-sperm antibodies form as a response to breach of the btb

autoimmune orchitis --> destruction of contralateral testis

40

Type Ad sperm stem cells do what?

undergo mitosis to maintain supply, line basal layer --> dark

41

Type Ap sperm stem cells do what?

undergo mitosis to produce clonal population, linked by cytoplasmic bridges --> mature simultaneously

42

What kind of sperm stem cells enter spermatogenesis and then spermiogenesis

Ap --> b

43

___ undergo meiosis 1

primary spermatocytes

44

____ undergo meiosis 2

secondary spermatocytes --> form spermatids

45

____ undergo spermiogenesis

spermatids

46

4 stages of spermiogenesis

golgi, cap, acrosome, maturation phases

47

____ phase is when a spermatid developes polarity

golgi phase

48

___ phase is when the spermatid nucleus condenses and forms a cap

cap phase

49

___ phase is when the acrosome matures and a tail develops

acrosome phase

50

____ phase is when excess spermatid is extruded into a residual body

maturation phase

51

Identification of primary hypogonadism

infertility precedes testosterone deficiency//fsh is elevated

52

Identification of secondary hypogonadism

same time infertility and testosterone deficiency // low fsh and lh

53

1st trimester hypogonadism leads to ___ and ___

ambiguous genitalia and hypospadias

54

2nd/3rd trimester hypogonadism leads to ___ and ___

micropenis and cryptorchidsm

55

Eunuchoid body proportions result from hypogonadism in what stage of life?

childhood (also pubertal delay/absence, and gynecomastia)

56

What are the associated hormone levels? normal men or obstruction

normal

57

What are the associated hormone levels? isolated spermatogenic failure

high fsh

58

What are the associated hormone levels? hypergonadotropic hypogonadism (aka testicular failure)

high fsh, high lh, low testosterone

59

What are the associated hormone levels? hypogonadtropic hypogonadism

low/normal fsh and lh, low testosterone

60

Most common cause of congenital primary hypogonadism

Klinefelter 47 xxy

61

increased risk of testicular cancer

klinefelter

62

Bell clapper deformity

malformation of processus vaginalis (acrquired hypogonadism)

63

testicular torsion and mumps orchitis can result in ____

acquired primary hypogonadism

64

When does gonadtropin therapy for secondary hypogonadism have best efficacy?

if onset of secondary hypogonadism occurred after puberty