Phys DSA (montemayor) - SRS Flashcards

(46 cards)

1
Q

What is another name for klinefelter syndrome?

A

•XXY Seminiferous Tubule Dysgenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What promotes the intrauterine development of the testes?

A

SRY gene produces TDF (testes determining factor)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What cells produce antimullerian hormone?

A

Sertoli cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What hormone action is needed for the wolfian duct to develop?

A

Testosterone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the wolfian duct structures?

A

seminal vesicles

ejaculatory duct

vas deferens

epididymus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which cells in the testes produce testosterone?

A

Leydig cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What hormone stimulates fetal leydig cell production of testosterone during development prior to fetal pit. LH?

A

HCG

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

•What is required for the development of the penis, scrotum and prostate?

A

–DHT (Dihydrotestosterone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

•What enzyme is required for the conversion of testosterone à DHT?

A

–5α-reductase-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

–5α-reductase-1 is more expressed in skin, so in what condition might this come into play?

A

Acne treatment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which binds tighter to their shared receptor, DHT or testosterone?

A

DHT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

5α-reductase-2 deficiencies lead to what phenotypical changes?

A

ambiguous or feminized external genitalia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What goes down at 6-8 weeks gestation in the male differentiation

A

Differentiation of testes

[SRY transcription factor]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens in weeks 8-9 of male gestational development (UG tract)

A
  • Retention of wolffian ducts
    • [Testosterone]
  • Regression of müllerian ducts
    • [Antimϋllerian hormone]
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens in weeks 9-13 of male genital development?

A

Male-type external genitalia

[DHT]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

In klinefelters, why the gynecomastia?

A

–Elevated estradiol levels and increased estradiol-to-testosterone ratio

–Peripheral conversion of testosterone à estradiol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

•Which enzyme converts androgen to estrogen?

A

–CYP19-aromatase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

•What hormone is considered to be responsible for the normal initiation of puberty?

A

–Resurgence of pulsatile sleep-associated GnRH secretion from the hypothalamus during adolescence, along with increased gonadotrope sensitivity to GnRH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

In this patient with Klinefelter Syndrome, increased levels of gonadotropins failed to induce normal testicular growth and spermatogenesis.

What happpens to the testes?

Seminiferous tubules?

A
  • The testis became fibrotic and hyalinized and remain small and firm.
  • The seminiferous tubules are largely destroyed and he is infertile.
20
Q

What hormones are affected and how in primary hypogonadism?

A

–Gonadotropin levels are elevated

–Androgen production is reduced

21
Q

What hormone is the key player in development of secondary sex characteristics, such as penis size, bear development, etc?

22
Q

What percent of testosterone circulates as….

–SHBG (sex hormone-binding globulin) bound:

–Serum albumin bound:

–Free:

A

–SHBG (sex hormone-binding globulin) bound: 45-60%

–Serum albumin bound: 38-55%

–Free: 2-5%

23
Q

•Which cells are the primary site for the production of testosterone in males?

24
Q

•What protein is responsible for maintaining testosterone concentration in the testes?

A

–ABP (androgen-binding protein)

25
•Why is it important for testosterone to be concentrated within the testes?
–Maintenance of adequate concentration [~ 100x \> circulating levels] within the testes is essential for the promotion of adequate spermatogenesis.
26
From cholesterol to testosterone, elaborate the intermediates in the production pathway.
1. Cholesterol 2. pregnenolone 3. progesterone 4. androstenedione 5. testosterone
27
Maintenance of adequate concentration [~ 100x \> circulating levels] within the testes is essential for the promotion of adequate spermatogenesis. Describe how this is accomplished.
Androgen binding protien (ABP) in the seminiferous tubules binds testosterone with high affinity.
28
What is testosterone converted to in peripheral tissues and by what?
Estradiol (CYP19-aromatase) DHT (5α-reductase-2)
29
•What promotes LH and FSH secretion?
–Pulsatile hypothalamic GnRH release stimulates anterior pituitary LH and FSH secretion
30
•Which cells are the target of LH in the testes?
–Leydig cells
31
•Which cells are the target of FSH in the testes?
–Sertoli cells
32
Sertoli cells have a number of functions, what general actions do these functions fall undeR?
Supportive function Exocrine function Endocrine function
33
What are the supportive functions of the sertoli cells?
**• Maintaining blood-testis barrier** * Phagocytosis * Transfer of nutrients to sperm **• Receptors for hormones & paracrines**
34
What are the exocrine functions of the sertoli cells?
* Fluid produced for sperm mobilization * Production of **ABP** (Androgen binding protein) * Spermination: release of sperm from seminiferous tubule
35
What are the endocrine functions of the sertoli cells?
* Expression of testosterone, ABP and FSH receptors * Production of **AMH** (Antimϋllerian hormone) * **CYP19 Aromatase:** testosterone à estradiol-17β (local) * Production of **inhibin B** to regulate FSH levels
36
In klinefelter, you will see low serum testosterone levels and elevated gonadotropin levels (LH and FSH). What is the explanation for elevated LH and FSH levels?
–Reduction in androgen production results in decreased negative feedback on the hypothalamic-pituitary-testicular axis
37
What does inhibin provide negative feedback on in men?
FSH
38
•Which 3 key hormones have an important function to promote adequate spermatogenesis in the normal male?
–Testosterone from Leydig cells –FSH & LH (necessary for Leydig and Sertoli function)
39
How does FSH contribute to spermatogenesis?
stimulates the Sertoli cells (nursing cells) to nurse and form sperm
40
Does estradiol have a role in spermatogenesis?
Yes, unclear what though
41
What role does GH have in development of sperm?
•. GH promotes early division of the sperm. Without it, as seen in pituitary dwarfs, spermatogenesis is severely deficient or absent resulting in infertility.
42
•What treatment might be suggested for this patient with Klinefelter Syndrome?
–Androgen replacement therapy
43
•What would be the likely effect of administering exogenous testosterone to a klinefelter patient? Can exogenous testosterone promote fertility in these patients? explain your answer.
–Virilization of secondary male sexual traits –No –Seminiferous tubule tissue is likely destroyed and the cause of infertility Also, in more detail... –Exogenous testosterone (T, DHT, and estradiol-17β) promotes negative feedback on gonadotropin secretion –↓ LH --\> further ↓ T production by Leydig cells --\> ↓ testicular [T] --\> ↓ spermatogenesis
44
What impact does defective steroidogenesis have on spermatogenesis?
•Normal spermatogenesis almost never occurs when steroidogenesis is defective May still have defective spermatogenesis though
45
In klinefelters why does a female phenotype fail to develop despite the presence of multiple X chromosomes?
–Antimϋllerian hormone --\> Mϋllerian duct regression
46