Male Reproductive System Flashcards
(138 cards)
1
Q
major functions of adult testes
A
spermatogenesis
steroid hormone synthesis
2
Q
steroid hormone synthesis in male testis occurs where
A
leydig cells
3
Q
spermatogeneis (when does it occur)
A
begins at puberty and continues well into senescence
4
Q
lower temp of testis is critical for what
A
normal spermatogenesis
5
Q
majority of estradiol in males is made where and from what
A
adipose tissue from testosterone
6
Q
androgens produced by testis are (which one is major)
A
testosterone (major)
androstenedione
DHEA
7
Q
testosterone is bound to what
A
sex hormone-binding globulin (SHBG)-40-60%
albumin
8
Q
what testosterone is bioavailable
A
free (2-3%)
bound to albumin (40-60%)
9
Q
LH receptor (what is it)
A
G-protein coupled receptor
activates cAMP pathway
10
Q
the LH receptor activates PKA which phosphorylates what to increase transcription of genes involved in steroidogenesis
A
CREB
11
Q
LH caused phosphorylation of CREB increases traslocation of what genes
A
StAR
CYP 11A (P450scc)
CPY 17 (17-alpha-hydroxylase/17,20lyase)
proteins/enzymes in cholesterol synthesis and uptake
12
Q
what happens to newly synthesized androgens
A
diffuse to neighboring seminiferous tubules and into capillaries where they enter systemic circulation
13
Q
testosterone can be converted into what
A
other biologically active steroids
excretory metabolites
14
Q
in some tissues testosterone is converted to what more potent androgen and by what
A
dihydrotestosterone (DHT) by
5-alpha-reductase
15
Q
give an example of an androgen effect that requires DHT not testosterone
A
virilization of external genitalia during embryonic development
16
Q
5-alpha-reductase inhibitors are useful for what
A
treating benign prostatic hyperplasia and prostate cancer
17
Q
testosterone can be metabolized by an aromatase enzyme to form what
A
estradiol
18
Q
where does aromatization of testosterone occur
A
certain CNS nuclei
Leydig and Sertoli Cells
adipose tissue
19
Q
inactivation of testosterone occurs primarily where
A
liver
20
Q
elimination of testosterone is enhanced if it is conjugated to what
A
glucuronic acid or sulfate
21
Q
leydig cells differentiate from what type of cells when
A
mesenchymal cells during weeks 8-9
22
Q
primary stimulus for early leydig cells is thought to be
A
hCG
23
Q
when do gonadotropins appear to be affecting testosterone secretion
A
mid-gestation
24
Q
levels of testosterone during childhood are what (whens the exception)
A
relatively low except at neonatal surge
25
the rise in testosterone during puberty corresponds to a rise in plasma concentrations of what
LH
26
what does LH do
promotes androgen biosynthesis in Leydig cells
27
what happens to androgen production in males over time
age-related decline in total serum testosterone begins 4-5th decade of life
28
what age-related event in males leads to a further decrease in bioavailable testosterone in men
age-related increase in SHBG
29
what type of receptor is the androgen receptor
ligand-activated transcription factor
30
androgen receptor has highest affinity for what
DHT
31
the androgen receptor binds DNA when
hormone is bound to its appropriate binding site on receptor
32
in the fetus androgens do what
promote the differentiation of male reproductive tract and external genitalia
33
at puberty androgens do what
promote growth and maturation of reproductive structures
| development of male secondary sexual characteristics
34
in adult androgens do what
maintain functional integrity of reproductive system
| enlargement of larynx and thickening of vocal cords
35
androgens promote what in terms of proteins
anabolism
36
androgens regulate what
spermatogenesis
37
in both genders androgens do what
promote hair and sebaceous gland growth
38
actions of androgens that aren't age specific
behavioral effects and libido
stimulate erythropoietin synthesis (increased hematocrit)
negative feedback on gonadotropin release
bone growth
39
testosterones actions on bone growth are mediated by what
estradiol
40
testosterone (via estradiol) promotes bone growth how
stimulate GH release
stimulate pubertal growth spurt
promote closure of epiphyseal plate
41
what lines the basal lamina of seminiferous tubules
Sertoli cells
42
principle function of sertoli cells is what
transfer nutrients from developing germ cells and create and environment that is conducive for germ cell differentiation into mature spermatozoa
43
what divides seminiferous tubules into two functional compartments
tight junctions between sertoli cells
44
the tight junctions b/w sertoli cells form what
"blood-testis" barrier
45
as primary spermatocytes migrate from basal compartment into adluminal compartment what happens
tight junctions disassemble and reassemble
46
what do sertoli cells phagocytize
cytoplasm released by spermatozoa during spermiogenesis
47
sertoli cells secrete what
Androgen Binding Protein (ABP)
Anti-Mullerian Hormone (AMH)
Inhibins and activins
Estradiol
48
Androgen Binding Protein (ABP)
| what is its function
serves to keep testosterone levels elevated in the seminiferous tubules and epididymis
49
ABP secreted from sertoli cells has the same structure as what
sex-hormone binding globulin from liver
50
what stimulates ABP secretion from sertoli cells
testosterone and FSH
51
sertoli cell function can be assessed by what
ABP secretion
| Inhibin B
52
sertoli cells secrete what that are members of the TGF-beta family
AMH
activins
inhibins
53
AMH (what does it do)
regression of mullein ducts in the male embryo
54
AMH (signal is transmitted how)
2 transmembrane serine-thronine kinase receptors
55
AMH binds what receptor
type II serine-threonine kinase
56
type II serine-threonine kinase receptor (what special about it)
constitutively phosphorylated receptor
57
AMH-bound type two receptor does what
recruits a type 1 receptor and phosphorylates it
58
phosphorylation of type 1 receptor by AMH bound type II receptor does what
activates kinase activity
59
activated type 1 serine-threonine receptor does what
phosphorylates Smad3
60
phosphorylation of Smad3 does what
unmasks its nuclear localization signal
61
phosphorylated Smad3 forms complex with what
other cytoplasmic proteins including non-phosphorylated co-Smad protein Smad4
62
complex of Smad3 and Smad4 does what
translocates to nucleus where it regulates transcription of genes that promote apoptosis
63
inhibins and activeness are what (in terms of structure)
dimers formed from different combinations of 3 distinct subunits held together by disulfide bonds
64
Inhibin B (what is it)
principle circulating inhibin in males
| plays role in feedback regulation of FSH
65
what stimulates inhibin B production
FSH and testosterone
66
inhibin B what is its effect
blocks GnRH-stimulated FSH release by gonadotropes
67
E2 is formed how
aromatization of androgens in response to FSH stimulation
68
what are the 3 phases of spermatogenesis
mitosis to increase number of spermatogenic
meiosis to provide haploid spermatids
spermiogenesis to transform immature spermatids to matrue spermatozoa
69
what is required to be functional for normal spermatogenesis in adults
functional Sertoli cells and intact hypothalamic-pituitary-gonadal axis (pulsatile release of GnRH)
70
what is important about the deliver of GnRH
pulsatile fashion
71
the principle target of FSH action is
spermatogonia
72
FSH actions
stimulates inhibin synthesis
73
what hormones are necessary for spermatogenesis
LH
FSH
testosterone
74
in human male what is only known cell to express FSH receptor
sertoli cell
75
FSH and testosterone work how together
synergistically
76
testosterones role in spermatogenesis
local regulator
77
low levels of intratesticular testosterone do what
result in decreased sperm production
78
blood-epididymis barrier (what is it made from)
tight epithelium of epididymis
79
how long to sperm spend maturing and where
a month
| epididymis
80
what happens to spermatozoa in epididymis
coated with substances that block acrosomal reaction (decapacitation)
81
decapacitation (what is it)
sperm not having acrosomal action
82
sperm storage sites are
epididymis
| vas deferens
83
Kallman Syndrome (what is it)
form of hypogonadism caused by failure of GnRH secreting cells to migrate from olfactory placode to hypothalamus during embryogenesis
84
Kallman Syndrome (signs/symtoms)
Low circulating levels of gonadotropes
| Symptoms of androgen deficiency become apparent at puberty and arrested spermatogenesis
85
release of pituitary gonadotropin is a function of what
concentration and pattern of GnRH release
86
normal secretory activity of gonadotrope requires what
intermittent delivery of GnRH
87
continuous exposure of GnRH does what to gonadotrope activity
suppresses it
| "functional castration"
88
gonadotropins are released in what kind of pattern
pulsatile
| secretory bursts
89
onset of puberty is associated with what
sleep associated surge in LH release
90
what is puberty
transition period where secondary sexual characteristics and reproductive competence develop
adolescent growth spurt also happens
91
in neonate HPG axis is under what control
CNS
92
what happens during puberty in terms of HPG axis
removal of CNS inhibitory effects on the activity of GnRH- releasing neurons
93
hypothalamic and pituitary changes associated with puberty are
decrease in sensitivity to the negative feedback of testosterone
increase amplitude of GnRH pulses
increase in sensitivity of gonadotropes to GnRH
94
during childhood the HPG axis is what
relatively quiescent
95
rising gonadotropin levels in the testes does what
promotes leydig maturation and secretory activity
promote differentiation and maturation of sertoli cells
initiate onset of spermatogenesis
increase in testicular volume
96
what promotes the anatomical and physiological changes normally associated with puberty
increase in circulating levels of testosterone
97
Stage 1 puberty in boys is
preadolescent development
98
Stage 2 of puberty in boys is
period where testes begin to enlarge
99
first clinical manifestation of puberty in boys
enlargement of testes
100
stage 3 of puberty in boys is
enlargement of penis
101
stage 4 in puberty in boys is
growth of glans penis
102
stage 5 of puberty in boys is
adult genitalia
103
what acts at the level of hypothalamus and may be important link b/w nutritional status and reproductive competence
leptin
104
what inhibits the hypothalamic pulse generator
testosterone
105
inhibit does what
inhibits FSH release
106
in the flaccid state what are the helicine arteries like
constricted (minimal blood flow)
107
what supplies the cavernous spaces of the penis with blood
helicine arteries
108
what covers the corpora cavernosa
tunica albuginea
109
rigidity of erection depends on
increase in flow of arterial blood (parasympathetics)
| decreased venous efflux from compression of venous plexus
110
erectile response is ignited how
tactile (low motor neuron reflex) or psychic (mediated over corticospinal pathways)
111
afferents of erection are transmitted how
pudendal nerve
112
efferent parasympathetic fibers do what
vasodilator the helicine arteries and sinusoidal spaces
113
efferent parasympathetics realize what vasodilatory for erection
NO and VIP
114
what can be used to treat erectile disfunction
cGMP specific phosphodiesterase inhibitors
115
mucus is secreted from what during sexual stimulation
urethral and bulbourethral glands
116
mucus secretion during sexual stimulation is mediated by what
parasympathetic nerves
117
what is emission
moment of semen into proximal part of urethra
118
emission involves what
coordinated rhythmic contractions of vas deferens, ampulla, prostate, and seminal vesicles
119
inhibin has what effect on LH
little or no
120
what mediates emissions
sympathetics in upper lumbar region of spinal cord
121
the mediation of emission is done how
norepi released on alpha 1 receptors
122
function of internal urethral sphincter in ejaculation
sympathetics constrict it preventing retrograde into the bladder
123
filling the urethra with semen does what
elicits sensory signals from pudendal nerve in the sacral portion
124
when in emission/ejaculation is the sacral portion of the spinal cord used
filling of urethra with semen
125
when in emission/ejaculation is the lumbar portion of the spinal cord used
mediating emissions
| hypogastric nerve
126
what triggers the rhythmic contraction of the started musculature of perineum
efferent signals from somatic efferent fibers in pudendal nerve
127
male orgasm is what
conscious awareness of contractions associated with ejaculations
128
systemic changes associated with male sexual response
increase in:
rate of respiration
heart rate
blood pressure
129
sympathetic stimulation of emission is done by what type of fibers and what neurotransmitter and what receptors
sympathetics
norepi
alpha 1
130
clinical manifestations of testicular dysfunctions are
infertility
decreased libido
lack of development of secondary sexual characteristics
131
testicular dysfunction before puberty (what features are apparent)
```
abnormal skeletal proportions
gynecomastia
sparse pubic, axillary, and facial hair
high pitched voice
infantile genitalia
poorly developed musculature
```
132
Gynecomastia (what is it)
estrogens have stimulatory effects on breast tissue while testosterone has inhibitory
so if a male has excessive estrogen exposure or decreased testosterone can get this
133
causes of primary hypogonadism
Klinefelter Syndrome
Orchitis
Irradiation
134
orchitis (what is it)
inflammation of testes
usually secondary to mumps
seminiferous tubule destruction
leydig cells not affected
135
irradiation of testicles affects what
seminiferous tubules more sensitive to irradiation than leydig cells
136
describe FSH, LH, estradiol, and testosterone levels in a patient with klinefelter
FSH and LH high
testosterone normal to low
estradiol high
137
what reproductive disorder is often associated with defective sense of smell
kallman
138
what reproductive disorder is often associated with fibrotic of hyalanized seminiferous tubules
klinefelter syndrome
