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Reproductive And Development > 2-22-16-Male Reproductive Physiology (Lopez) > Flashcards

2-22-16-Male Reproductive Physiology (Lopez) Flashcards

1
Q

At puberty, pulsatile secretion of FSH and LH stimulates secretion of ___

A

Gonadal steroid hormones, testosterone, and estradiol

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2
Q

What happens if a GnRH analogue is administered in intermittent pulses?

A

If it is administered in intermittent pulses to replicate the normal pulsatile secretion, puberty is initiated and reproductive function is established

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3
Q

What happens if a long-acting GnRH analogue is administered?

A

Puberty is not initiated

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4
Q

Extreme stress or caloric deprivation in girls may have what effect on the onset of puberty?

A

Delayed

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5
Q

___ may be a natural inhibitor of GnRH

A

Melatonin

Melatonin levels are highest during childhood and decline in adulthood

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6
Q

Removal of the pineal gland may precipitate ___

A

Early puberty

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7
Q

The testes 2 main functions are:

A

1) spermatogenesis

2) secrete testosterone

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8
Q

___ is the primary location for the maturation and storage of sperm

A

Epididymis

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9
Q

___ provides another storage area for sperm (ampulla) and secretes fluid rich in citrate and fructose

A

Vas deferens

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10
Q

___ secretes fluid rich in citrate, fructose, PGs, and fibrinogen

A

Seminal vesicles

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11
Q

___ secretes a milk aq. Soln rich in citrate, calcium, and enzymes

A

Prostate gland

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12
Q

___ is epithelium formed by the sertoli cells, with interspersed germ cells

A

The seminiferous tubule

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13
Q

___ are the most immature germ cells, located near the periphery of the seminiferous tubule

A

Spermatogonia

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14
Q

___ are mature germ cells, located near the lumen of the seminiferous tubule

A

Spermatozoa

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15
Q

___ are interstitial cells that lie between the seminiferous tubules

A

Leydig cells

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16
Q

___ provide nutrients to differentiating sperm, form tight junctions with each other to create a barrier between testes and bloodstream, and secrete an aqueous fluid into the lumen of the seminiferous tubules

A

Sertoli cells

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17
Q

___ synthesize and secrete testosterone

A

Leydig cells

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18
Q

Androgens secreted by the testes include:

A

Testosterone, DHT, and androstenedione

Testosterone is the most abundant

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19
Q

In target tissues, much of the testosterone is eventually converted into the more active hormone ___

A

DHT

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20
Q

In the testis, the main steroidogenic cells are the __ cells

A

Leydig

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21
Q

___ cells are responsible for masculinizing the male urogenital tract and induce testis descent

A

Fetal leydig–> these cells atrophy shortly after birth and do not contribute to the adult leydig cell population

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22
Q

___ cells derive from undifferentiated precursors present after birth and become fully steroidogenic at puberty

A

Adult leydig

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23
Q

___ can synthesize cholesterol de novo and can also acquire cholesterol from the circulation, through LDL receptors, and to a lesser extent through HDL receptors

A

Leydig cells

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24
Q

Leydig cells store cholesterol as ___

A

Cholesterol esters

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25
Q

___ converts cholesterol esters to free cholesterol for androgen production in leydig cells

A

HSL

Cholesterol is then transferred within the mt membrane via the StAR

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26
Q

In leydig cells, cholesterol is converted to ___

A

Pregnenolone

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27
Q

The testes lack __ enzymes and no glucocorticoids or mineralocorticoids are synthesized

A

21-beta-hydroxylase and 11-beta-hydroxylase

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28
Q

The testes contain ___ enzyme which helps convert androstenedione to testosterone

A

17-beta-hydroxysteroid dehydrogenase

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29
Q

In the lumen of the seminiferous tubules, Testosterone is concentrated by binding to ___

A

Androgen binding protein (ABP)

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30
Q

In peripheral tissues, ___ enzyme converts testosterone to DHT

A

5-alpha-reductase

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31
Q

Where would you find high [estrogen] in males?

A

In the fluid of the seminiferous tubules

-Source of estrogen might be sertoli cells but exact source of estrogen is unknown

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32
Q

What is the rate-limiting step in the synthesis of testosterone?

A

Conversion of cholesterol to pregnenolone with desmolase and is mediated by the StAR which transfers cholesterol from inner to outer mt membrane

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33
Q

Synthesis and secretion of testosterone occurs in __ cells

A

Leydig

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34
Q

In seminiferous tubules, T is concentrated by binding to ___ and T is carried in the peripheral circulation by ___

A

ABP

SHBG and albumin

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35
Q

The leydig cells make limited amounts of DHT and estradiol-17-beta, but considerably more of these steroids is made by ___

A

Peripheral conversion

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36
Q

___ stimulates the conversion of cholesterol to pregnenolone and regulates the overall rate of testosterone synthesis by the leydig cell

A

LH

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37
Q

List two ways in how LH promotes pregenenolone synthesis:

A
  • Increases affinity of P450SCC enzyme for cholesterol

- Long term action in which it stimulates synthesis of P450SCC enzyme

38
Q

The androgen receptor complex is a __ receptor which directs protein synthesis

A

Nuclear

39
Q

___ binds to androgen receptors with greater affinity than T, and plays an important role in causing changes at puberty

A

DHT

40
Q

Deficiency of ___ results in ambiguous external genitalia

A

5-alpha-reductase

41
Q

about 60% of circulating T is bound to ___

About 38% of circulating T is bound to ___

About 2% is ___ which is the most important biological form

A

SHBG

Albumin

remains as Free T

42
Q

About 50% of excreted androgens are found as urinary ___

A

17-ketosteroids

Remainder being conjugated androgens or diol or triol derivatives

43
Q

In peripheral tissues, testosterone is converted to estradiol by __

A

Aromatase

44
Q

The presence of testosterone during embryonic life in the male results in development of __, while absence of T during embryonic life in the male results in the development of ___

A

+ T=penis, scrotum

  • T= clitoris and vagina
45
Q

Describe 2 fetal actions of T:

A
  • Fetal differentiation of the internal male genital tract (epididymis, vas deferens, and seminal vesicles)
  • Causes descent of testes into scrotum during last 2-3 months of pregnancy (Lack of descent=Cryptorchidism)
46
Q

List T actions at puberty:

A
  • Increase muscle mass
  • Pubertal growth spurt
  • Closure of epiphyseal plates
  • Growth of penis and seminal vesicles
  • Deepening of voice
  • Spermatogenesis
  • Libido
47
Q

Fetal differentiation of external male genitalia (penis, scrotum, and prostate), male hair distribution and male pattern baldnes, sebaceous gland activity, and growth of the prostate are all specific actions of ___

A

DHT

48
Q

Because the growth of the prostate gland and male pattern baldness depends on DHT rather than T, ___ can be used as tx for benign prostatic hypertrophy and hair loss in males

A

5-alpha-reductase inhibitors

49
Q

Puberty in males and females is initiated by pulsatile secretion of ___, which drives the pulsatile secretion of FSH and LH

A

GnRH

50
Q

On the leydig cell, the LH receptor pathway is couple to a ___ second messenger pathway resulting in steroidogenesis and testosterone production. The testosterone produced then diffuses into seminiferous tubules and peripheral circulation

A

Cyclic AMP-PKA

51
Q

Sertoli cells are stimulated by testosterone and FSH. The FSH receptor is coupled to a ___ second messenger pathway is involved in protein synthesis and production of __ which inhibits FSH release

A

cAMP-PKA pathway

Inhibin

52
Q

____ stimulates the sertoli cells to secrete androgen-binding protein into the lumen of the seminiferous tubules.

Binding of testosterone in the lumen provides a local testosterone supply for the developing ___

A

FSH

Spermatogonia

53
Q

List supportive functions of sertoli cells:

A
  • Maintain blood-testis barrier
  • Phagocytosis
  • Transfer of nutrients from blood to sperm (transferrin, Fe, lactate)
  • Receptors for hormones and paracrines
54
Q

List exocrine functions of sertoli cells:

A
  • Production of fluid
  • Production of ABP
  • Determination of release of sperm from seminiferous tubule
55
Q

List endocrine functions of sertoli cells:

A
  • Expression of testosterone, ABP, and FSH receptors
  • Production of AMH
  • Aromatization of testosterone to estradiol-17-beta
  • production of inhibin to regulate FSH levels
56
Q

Where does spermatogenesis take place?

A

Occurs along the seminiferous tubules

57
Q

The seminiferous tubules are lined by a complex stratified epithelium containing 2 distinct populations of cells:
___ cells develop into spermatozoa
___ cells which have a supportive and nutrient function

A

Spermatogenic

Sertoli

58
Q

__ cells are the epithelial supporting cells of the seminiferous tubules, are tall simple columnar cells which span from the basement membrane to the lumen, surround proliferating and differentiating germ cells forming pockets around these cells, and are connected to each other by continuous tight junctions that seal the tubule into 2 compartments

A

Sertoli

59
Q

After the last mitotic division, the resulting cells are called ___

A

Primary spermatocytes

60
Q

The first meiotic division produces __, each with a haploid number of duplicated chromosomes

A

2 secondary spermatocytes

61
Q

Secondary spermatocytes enter the 2nd meiotic division, producing ___, each with a haploid number of unduplicated chromosomes

A

2 spermatids

62
Q

During spermiogenesis (maturation), spermatids undergo spermiogenesis and mature into ___

A

Spermatozoa

  • Nuclear and cytoplasmic changes to produce mature spermatozoa
  • End in testis with release of spermatozoa from sertoli cells
63
Q

___ is secreted by the A.P. And stimulates leydig cells to secrete testosterone

A

LH

64
Q

___ is secreted by leydig cells and are essential for growth and division of the testicular germinal cells, which is beginning of sperm formation

A

Testosterone

65
Q

___ is secreted by the A.P. And stimulates sertoli cells to nurse and form sperm. Without this stimulation, spermiogenesis will not occur

A

FSH

66
Q

___ is formed from the testosterone by the sertoli cells when they are stimulated by FSH. It may be essential for spermatogenesis

A

Estrogens

67
Q

___ is necessary for controlling background metabolic functions of the testes. It promotes early division of the sperm themselves. Without it, spermatogenesis is severely deficient or absent rendering them infertile

A

GH

68
Q

Decapacitation occurs in the ___ which involves adding molecules to the membranes of sperm to prevent the acrosomal reaction before contact with an egg. The function is dependent on testosterone-ABP and can act as a storage site for mature sperm for several months

A

Epididymis

69
Q

___ secretes a mucoid material containing fructose, citric acid, and other nutrients. It adds considerable nutrient value for the ejaculated sperm and the PG’s aid in fertilization

A

Seminal vesicles

70
Q

___ aids in fertilization and reacts with the female cervical mucus to make it more receptive to sperm movement and can cause backward, reverse peristaltic contractions in the uterus and fallopian tubes to move the ejaculated sperm toward the ovaries

A

PGs

71
Q

___ secretes a thin, milky fluid that contains Ca, citrate ion, Phosphate ion, a clotting enzyme, and a profibrinolysin (secreted during emission). It also helps neutralize the acidity of the other seminal fluids during ejaculation and thus enhances the motility and fertility of sperm

A

Prostate gland

72
Q

What is the final pH of semen?

A

About 7.5–> alkaline prostatic fluid neutralizes the mild acidity of other semen components

73
Q

Beginning with the efferent ductules, trace the path that spermatozoa take until ejaculation:

A

Efferent ductules –> extra testicular portion of male repro tract –> epididymis (head, body, tail), vas deferens, ejaculatory duct –> prostatic urethra –> membranous urethra –> penile urethra

74
Q

Penile urethra runs through the ___

What are the 3 erectile bodies (tissue) in the penis?

A

Corpus spongiosum

2 corpora cavernosa and 1 corpus spongiosum

75
Q

Describe the role of NO in an erection:

A

NO activates guanylyl cyclase –> increases cGMP –> decreases IC Ca and causes relaxation of vascular smooth muscle

-Vasodilation allows blood to flow into the spaces, causing engorgement and erection

76
Q

Viagra is a __ inhibitor

A

Type 5 phosphodiesterase

77
Q

Emission is under ___ control

A

Sympathetic (adrenergic transmitter)

78
Q

__ is the movement of semen from the epididymis, vas deferens, seminal vesicles, and prostate to the ejaculatory ducts

__ is the propulsion of semen out of the male urethra

A

Emission

Ejaculation

79
Q

Ejaculation is caused by contraction of what muscles and are innervated by what type of nerves?

A

Bulbospongiosus and ischicavernosus

Somatic motor nerves

80
Q

When the membrane of sperm is more permeable to __, motility of the sperm increases

A

Ca2+

81
Q

Stored in the acrosomal head of the sperm are large quantities of ___

A

Hyaluronidase and proteloytic enzymes

82
Q

In the sperm acrosome rxn, __ depolymerizes the hyaluronic acid polymers in the IC cement that hold the ovarian granulosa cells together

The ___ digest proteins in the structural elements of tissue cells that adhere to the ovum

A

Hyaluronidase

Proteolytic enzymes

83
Q

T deficiency in the 3rd trimester of pregnancy results in what?

A

Leads to problems in testicular descent (cryptorchidism) along with micropenis

84
Q

T deficiency at puberty leads to what?

A

Poor secondary sexual development and overall eunuchoid features

85
Q

T deficiency post-puberty results in what?

A

Decreased libido, ED, decrease facial and body hair growth, low energy, infertility

86
Q

___ is usually caused by genetic inability to produce GnRH, resulting in low T levels and is thus associated with infantile sex organs

A

Male hypogonadism

Gonadal failure/sex steroid synthesis failure can lead to hypogonadism

87
Q

___ is a genetic disorder, occurs when the hypothalamic neurons that are responsible for releasing GnRH neurons fail to migrate into the hypothalamus during embryonic development

A

Kallman’s syndrome

88
Q

__ is AKA seminiferous tubular dysgenesis and it is men with an extra X chromosome. Those affected are phenotypically male b/c of presence of Y chromosome and appear normal at birth. At puberty, increased levels of gonadotropins fail to induce normal testicular growth and spermatogenesis. Androgen production is usually low. Seminiferous tubules are largely destroyed, resulting in infertility

A

Klinefelter syndrome

89
Q

List the levels of T and LH in primary hypogonadism

List the levels of T and LH in secondary hypogonadism

A

Decreased T, Increased LH, Cause=Testicular dysfunction (klinefelters), effect=Decreased T secretion

Decreased T and Decreased or normal LH, Cause=pituitary (tumor) or hypothalamic dysfunction (kallmans), effect=Decreased GnRH secretion

90
Q

Male pattern baldness can be treated with a ___

Benign prostatic hypertrophy can be treated with a __

Cancer of the prostate can be treated with ___

A

5-alpha-reductase inhibitor

5-alpha-reductase inhibitor

Androgen receptor antagonist, radiotherapy, radical prostatectomy

Reproductive And Development (16 decks)

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