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
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
3
Q
What happens if a long-acting GnRH analogue is administered?
A
Puberty is not initiated
4
Q
Extreme stress or caloric deprivation in girls may have what effect on the onset of puberty?
A
Delayed
5
Q
___ may be a natural inhibitor of GnRH
A
Melatonin
Melatonin levels are highest during childhood and decline in adulthood
6
Q
Removal of the pineal gland may precipitate ___
A
Early puberty
7
Q
The testes 2 main functions are:
A
1) spermatogenesis
2) secrete testosterone
8
Q
___ is the primary location for the maturation and storage of sperm
A
Epididymis
9
Q
___ provides another storage area for sperm (ampulla) and secretes fluid rich in citrate and fructose
A
Vas deferens
10
Q
___ secretes fluid rich in citrate, fructose, PGs, and fibrinogen
A
Seminal vesicles
11
Q
___ secretes a milk aq. Soln rich in citrate, calcium, and enzymes
A
Prostate gland
12
Q
___ is epithelium formed by the sertoli cells, with interspersed germ cells
A
The seminiferous tubule
13
Q
___ are the most immature germ cells, located near the periphery of the seminiferous tubule
A
Spermatogonia
14
Q
___ are mature germ cells, located near the lumen of the seminiferous tubule
A
Spermatozoa
15
Q
___ are interstitial cells that lie between the seminiferous tubules
A
Leydig cells
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
17
Q
___ synthesize and secrete testosterone
A
Leydig cells
18
Q
Androgens secreted by the testes include:
A
Testosterone, DHT, and androstenedione
Testosterone is the most abundant
19
Q
In target tissues, much of the testosterone is eventually converted into the more active hormone ___
A
DHT
20
Q
In the testis, the main steroidogenic cells are the __ cells
A
Leydig
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
22
Q
___ cells derive from undifferentiated precursors present after birth and become fully steroidogenic at puberty
A
Adult leydig
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
24
Q
Leydig cells store cholesterol as ___
A
Cholesterol esters
25
___ converts cholesterol esters to free cholesterol for androgen production in leydig cells
HSL
Cholesterol is then transferred within the mt membrane via the StAR
26
In leydig cells, cholesterol is converted to ___
Pregnenolone
27
The testes lack __ enzymes and no glucocorticoids or mineralocorticoids are synthesized
21-beta-hydroxylase and 11-beta-hydroxylase
28
The testes contain ___ enzyme which helps convert androstenedione to testosterone
17-beta-hydroxysteroid dehydrogenase
29
In the lumen of the seminiferous tubules, Testosterone is concentrated by binding to ___
Androgen binding protein (ABP)
30
In peripheral tissues, ___ enzyme converts testosterone to DHT
5-alpha-reductase
31
Where would you find high [estrogen] in males?
In the fluid of the seminiferous tubules
-Source of estrogen might be sertoli cells but exact source of estrogen is unknown
32
What is the rate-limiting step in the synthesis of testosterone?
Conversion of cholesterol to pregnenolone with desmolase and is mediated by the StAR which transfers cholesterol from inner to outer mt membrane
33
Synthesis and secretion of testosterone occurs in __ cells
Leydig
34
In seminiferous tubules, T is concentrated by binding to ___ and T is carried in the peripheral circulation by ___
ABP
SHBG and albumin
35
The leydig cells make limited amounts of DHT and estradiol-17-beta, but considerably more of these steroids is made by ___
Peripheral conversion
36
___ stimulates the conversion of cholesterol to pregnenolone and regulates the overall rate of testosterone synthesis by the leydig cell
LH
37
List two ways in how LH promotes pregenenolone synthesis:
- Increases affinity of P450SCC enzyme for cholesterol
| - Long term action in which it stimulates synthesis of P450SCC enzyme
38
The androgen receptor complex is a __ receptor which directs protein synthesis
Nuclear
39
___ binds to androgen receptors with greater affinity than T, and plays an important role in causing changes at puberty
DHT
40
Deficiency of ___ results in ambiguous external genitalia
5-alpha-reductase
41
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
SHBG
Albumin
remains as Free T
42
About 50% of excreted androgens are found as urinary ___
17-ketosteroids
Remainder being conjugated androgens or diol or triol derivatives
43
In peripheral tissues, testosterone is converted to estradiol by __
Aromatase
44
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 ___
+ T=penis, scrotum
- T= clitoris and vagina
45
Describe 2 fetal actions of T:
- 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
List T actions at puberty:
- Increase muscle mass
- Pubertal growth spurt
- Closure of epiphyseal plates
- Growth of penis and seminal vesicles
- Deepening of voice
- Spermatogenesis
- Libido
47
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 ___
DHT
48
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
5-alpha-reductase inhibitors
49
Puberty in males and females is initiated by pulsatile secretion of ___, which drives the pulsatile secretion of FSH and LH
GnRH
50
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
Cyclic AMP-PKA
51
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
cAMP-PKA pathway
Inhibin
52
____ 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 ___
FSH
Spermatogonia
53
List supportive functions of sertoli cells:
- Maintain blood-testis barrier
- Phagocytosis
- Transfer of nutrients from blood to sperm (transferrin, Fe, lactate)
- Receptors for hormones and paracrines
54
List exocrine functions of sertoli cells:
- Production of fluid
- Production of ABP
- Determination of release of sperm from seminiferous tubule
55
List endocrine functions of sertoli cells:
- 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
Where does spermatogenesis take place?
Occurs along the seminiferous tubules
57
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
Spermatogenic
Sertoli
58
__ 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
Sertoli
59
After the last mitotic division, the resulting cells are called ___
Primary spermatocytes
60
The first meiotic division produces __, each with a haploid number of duplicated chromosomes
2 secondary spermatocytes
61
Secondary spermatocytes enter the 2nd meiotic division, producing ___, each with a haploid number of unduplicated chromosomes
2 spermatids
62
During spermiogenesis (maturation), spermatids undergo spermiogenesis and mature into ___
Spermatozoa
- Nuclear and cytoplasmic changes to produce mature spermatozoa
- End in testis with release of spermatozoa from sertoli cells
63
___ is secreted by the A.P. And stimulates leydig cells to secrete testosterone
LH
64
___ is secreted by leydig cells and are essential for growth and division of the testicular germinal cells, which is beginning of sperm formation
Testosterone
65
___ is secreted by the A.P. And stimulates sertoli cells to nurse and form sperm. Without this stimulation, spermiogenesis will not occur
FSH
66
___ is formed from the testosterone by the sertoli cells when they are stimulated by FSH. It may be essential for spermatogenesis
Estrogens
67
___ 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
GH
68
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
Epididymis
69
___ 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
Seminal vesicles
70
___ 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
PGs
71
___ 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
Prostate gland
72
What is the final pH of semen?
About 7.5--> alkaline prostatic fluid neutralizes the mild acidity of other semen components
73
Beginning with the efferent ductules, trace the path that spermatozoa take until ejaculation:
Efferent ductules --> extra testicular portion of male repro tract --> epididymis (head, body, tail), vas deferens, ejaculatory duct --> prostatic urethra --> membranous urethra --> penile urethra
74
Penile urethra runs through the ___
What are the 3 erectile bodies (tissue) in the penis?
Corpus spongiosum
2 corpora cavernosa and 1 corpus spongiosum
75
Describe the role of NO in an erection:
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
Viagra is a __ inhibitor
Type 5 phosphodiesterase
77
Emission is under ___ control
Sympathetic (adrenergic transmitter)
78
__ 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
Emission
Ejaculation
79
Ejaculation is caused by contraction of what muscles and are innervated by what type of nerves?
Bulbospongiosus and ischicavernosus
Somatic motor nerves
80
When the membrane of sperm is more permeable to __, motility of the sperm increases
Ca2+
81
Stored in the acrosomal head of the sperm are large quantities of ___
Hyaluronidase and proteloytic enzymes
82
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
Hyaluronidase
Proteolytic enzymes
83
T deficiency in the 3rd trimester of pregnancy results in what?
Leads to problems in testicular descent (cryptorchidism) along with micropenis
84
T deficiency at puberty leads to what?
Poor secondary sexual development and overall eunuchoid features
85
T deficiency post-puberty results in what?
Decreased libido, ED, decrease facial and body hair growth, low energy, infertility
86
___ is usually caused by genetic inability to produce GnRH, resulting in low T levels and is thus associated with infantile sex organs
Male hypogonadism
Gonadal failure/sex steroid synthesis failure can lead to hypogonadism
87
___ 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
Kallman's syndrome
88
__ 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
Klinefelter syndrome
89
List the levels of T and LH in primary hypogonadism
List the levels of T and LH in secondary hypogonadism
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
Male pattern baldness can be treated with a ___
Benign prostatic hypertrophy can be treated with a __
Cancer of the prostate can be treated with ___
5-alpha-reductase inhibitor
5-alpha-reductase inhibitor
Androgen receptor antagonist, radiotherapy, radical prostatectomy
