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A Physiology > 7.7B. Male reproductive physiology > Flashcards

7.7B. Male reproductive physiology Flashcards

1
Q

I. Basics
1. What are the main features of MALE REPRODUCTIVE PHYSIOLOGY?

A
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2
Q

I. Basics
2. Describe anatomy of male reproductive system

A
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3
Q

I. Basics
3A. What are the 2 main compartments of testicular lobule?

A
  1. Intratubular compartment
  2. Peritubular compartment
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4
Q

I. Basics
3C. What are the features of Peritubular compartment?

A
  • Neurovascular elements
  • CT
  • Immune cells
  • Interstitial cells of Leydig (testosterone production)
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5
Q

I. Basics
3B. What are the features of Intratubular compartment?

A

Seminiferous epithelium is composed of:
- Sperm cells (in different phases of spermatogenesis)
- Sertolli cells – responsible for ‘’nursing’’ + maintenance of
developing sperm cells

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6
Q

II. Spermatogenesis
1. What are the requirements for Spermatogenesis?

A

The process from spermatogonium to fully developed sperm cells
- Takes ~72 days, spend ~50 days in the testis
- Vitamin A is essential

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7
Q

II. Spermatogenesis
2. What are the 4 steps of spermatogenesis?

A
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8
Q

II. Spermatogenesis
3. What will Spermatogonia undergo?

A

permatogonia will undergo mitosis to replicate themselves to make more spermatogonia (will remain at basal lamina), or become primary spermatocytes

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9
Q

II. Spermatogenesis
4. What will Primary spermatocytes undergo?

A

Primary spermatocytes (diploid 4N DNA) will undergo meiosis 1 (chromosomal duplication, synapsis, crossing over, homologous recombination)
=> to form 2 secondary spermatocytes (they get closer to the lumen of tubule)

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10
Q

II. Spermatogenesis
5. What will Secondary spermatocytes undergo?

A

The 2 secondary spermatocytes (haploid 2N DNA) carry out meiosis 2 to result in the formation of 4 haploid spermatids

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11
Q

II. Spermatogenesis
6. What will Spermatids undergo?

A

Spermatids remain interconnected with cytoplasmic bridges that provide the development and differentiation of these cells
=> Spermatids will move through the seminiferous tubules, until they reach the head of epididymis, where they are still not mature!

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12
Q

III. Spermiogenesis
1. What is Spermiogenesis

A

Spermiogenesis: maturation of the spermatozoa
- Size of the nucleus decreases
- Tail formation
- Acrosome development: contains protease enzymes + other mediators that are
essential for the insemination of the X-cell

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13
Q

III. Spermiogenesis
2. What happen in Spermiogenesis?

A
  • Size of the nucleus decreases
  • Tail formation
  • Acrosome development: contains protease enzymes + other mediators that are essential for the insemination of the X-cell
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14
Q

III. Spermiogenesis
3. What happen in acrosome development?

A

Contains protease enzymes other mediators that are essential for the insemination of the X-cell

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15
Q

IV. What is Spermiation?

A

The completely developed sperm cell will leave the seminiferous epithelium and is released into the lumen of the seminiferous tubules

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16
Q

V. Sertoli cells
1. What are Sertoli cells?

A

Epithelial cells that line the seminiferous tubules
=> nurse developing sperm cells

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17
Q

V. Sertoli cells
2A. How do Sertoli cells keep communicate with other cells? (IMPORTANT)

A
  1. They maintain adherens + gap junctions with developing sperm cells
  2. Tight junctions with adjacent Sertoli cells, which create 2 sub-compartments: basal and apical apartment
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18
Q

V. Sertoli cells
2B. How do Sertoli cells maintain adherens + gap junctions with developing sperm cells?

A
  • Guide developing sperm cells from the basal lamina to the lumen of seminiferous tubules
  • Breakdown of these connections will lead to spermiation
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19
Q

V. Sertoli cells
2C. Tight junctions with adjacent Sertoli cells, which create 2 sub-compartments: Apical and basal compartments
=> What are the characteristics of basal compartment?

A

Contains spermatogonia + early primary spermatocytes

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20
Q

V. Sertoli cells
2D. Tight junctions with adjacent Sertoli cells, which create 2 sub-compartments: Apical and basal compartments
=> What are the characteristics of Adluminal/apical compartment?

A
  • This compartment contains late primary spermatocyte and all later forms
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21
Q

V. Sertoli cells
3. What is the role of the Blood-testis-barrier (BTB)?

A

Blood-testis-barrier (BTB): Creates a specialized
immunologically safe microenvironment for developing sperm

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22
Q

V. Sertoli cells
4. What are the features of Blood-testis-barrier (BTB)?

A
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23
Q

V. Sertoli cells
5A. What are the 5 main functions of Sertoli cells?

A

(GFs, fluid production, phagocytosis of residual bodies)
1. Receptor expression
2. CYP19 (aromatase) expression
3. Androgen binding protein (ABP)
4. Endocrine functions
5. Cell-cell interactions

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24
Q

V. Sertoli cells
5B. One of the main functions of Sertoli cells is
“RECEPTOR EXPRESSION”
=> Explain

A
  • Androgen receptor (responds to testosterone)
  • FSH receptor (binds FSH + stimulates Sertoli cell function)
  • These hormones regulate spermatogenesis indirectly
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25
Q

V. Sertoli cells
5C. One of the main functions of Sertoli cells is
“CYP19 (aromatase) expression:”
=> Explain

A
  • Conversion of testosterone to estradiol
  • Estradiol important in spermatogenesis, because developing sperm cells express estradiol receptors
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26
Q

V. Sertoli cells
5D. One of the main functions of Sertoli cells is
“Androgen binding protein (ABP)”
=> Explain

A

Binds testosterone in the lumen of seminiferous tubules
=> maintains high intraluminal [testosterone], which is essential for maintenance of spermatogenesis

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27
Q

V. Sertoli cells
5E. One of the main functions of Sertoli cells is
“Endocrine functions”
=> Explain

A
  1. Anti-müllerian hormone (AMH) will during development induce regression of the Müllerian duct (female reprod.tract)
    => is maintained throughout life
  2. Inhibin (heterodimer protein) belongs to the TFG-β family
    => responsible for regulation of testosterone production
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28
Q

V. Sertoli cells
5E. One of the main functions of Sertoli cells is
“Cell-cell interactions”
=> Explain

A

ICAM (intracellular adhesion molecule) is important in binding of sperm cells to the Sertoli cells during their maturation

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29
Q

VI. Leydig cells
1. Which compartment can you find Leydig cells?

A

peritubular compartment

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30
Q

VI. Leydig cells
2. What are the features of Leydig cells?

A
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31
Q

VII. Androgen production in the testes
1. How is androgen produced in the testes?

A
  • Free cholesterol is transferred into the mitochondrial matrix in a steroidogenic acute regulatory (StAR) protein dependent manner.
  • Androgen production in the Leydig cells
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32
Q

VII. Androgen production in the testes
2. Make a schematic diagram of Androgen production in the testes

A
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33
Q

VII. Androgen production in the testes - Intratesticular androgen
3A. Explain the fate of Intratesticular androgen

A
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34
Q

VII. Androgen production in the testes - Intratesticular androgen
3B. What is the role of Aromatase?

A

Aromatase converts testosterone into estradiol

35
Q

VII. Androgen production in the testes - Intratesticular androgen
3C. What are the receptors for Leydig cells and Sertoli cells?

A
  • Leydig cells have LH receptors, while Sertoli cells have FSH receptors (both Gs)
    => both will lead to new protein synthesis
36
Q

VII. Androgen production in the testes - Extratesticular androgen
4. What does Extratesticular androgen mean?

A

testosterone that leaves the testis

37
Q

VII. Androgen production in the testes - Extratesticular androgen
5. How are androgens transported?

A

Androgens are transported in the (peripheral) circulatory system with the help of sex hormone binding globulin (SHBG)

38
Q

VII. Androgen production in the testes - Extratesticular androgen
6. What is the fate of testosterone in adipose tissue?

A

Adipose tissue: testosterone is converted into estradiol-17β by aromatase (CYP19)

39
Q

VII. Androgen production in the testes - Extratesticular androgen
6A. What is the fate of testosterone in Genital skin + prostate?

A

Genital skin + prostate: testosterone is converted into
dihydrotestosterone (DHT) by 5α-reductase

40
Q

VII. Androgen production in the testes - Extratesticular androgen
6B. What are the features of dihydrotestosterone (DHT)?

A
  1. Has much higher affinity for binding to androgen receptors
  2. The most active form of androgens that can be found is DHT
41
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone

7A. How is testosterone transported in the circulation?

A

Adipose tissue: testosterone is converted into estradiol-17β by aromatase (CYP19)

42
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
7B. What is the % of albumin-bound testosterone?

A
  • Albumin-bound = 50% (low affinity for testosterone, but albumin is abundant in blood)
43
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
7C. What is the % of SHBG-bound testosterone?

A
  • SHBG-bound = 45% (high affinity for testosterone, but SHBG is scarce in blood)
44
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
7D. What is the % of CBG-bound testosterone?

A
  • CBG-bound (corticosteroid-binding-globulin) = 4%
45
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
7E. What is the % of free testosterone? What is its fate?

A
  • Free testosterone = 1-3%
    => can be converted into estradiol (aromatase-CYP19) and DHT (5α-reductase)
46
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
8. Is testis the only source of androgens? Why?

A

The testis is not the sole source of androgens: adrenal DHEA(S) is the main source in women, but biologically negligible in healthy mean

47
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
9. What are Pleiotropic effects of testosterone?

A

Testosterone is responsible for
- development of internal male genitalia (epididymis, vas deferens, seminal vesicle)
- growth of penis
- sperm production
- imprinting of male pattern of gonadotropins
- sexual drive + behavior and deepening of voice

48
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
9. What is the role of Dihydrotestosterone?

A

Dihydrotestosterone is responsible for
- development of external male genitalia (penis, scrotum, urethra, prostate)
- beard growth
- sebum formation + pubertal development
=> all together with testosterone

49
Q

VII. Androgen production in the testes - Transport and metabolism of testosterone
10. Is testosterone important in both sexes? How?

A
50
Q

VIII. Hypothalamic-pituitary-gonadal axis
1. Which hormone(s) that regulate testis?

A

The testis is regulated by LH and FSH

51
Q

VIII. Hypothalamic-pituitary-gonadal axis
2. What are the features of regulation of testis?

A
52
Q

VIII. Hypothalamic-pituitary-gonadal axis
3A. What is the general molecular mechanism of LH & FSH?

A
53
Q

VIII. Hypothalamic-pituitary-gonadal axis
3B. What is the molecular mechanism of LH receptor?

A

Leydig cells express the LH receptor (Gs-coupled):
- Increases the expression of enzymes and other proteins required for testosterone production (Sterol carrier protein and StAR)

54
Q

VIII. Hypothalamic-pituitary-gonadal axis
3B. What is the molecular mechanism of FSH receptor?

A

Sertoli cells express the FSH receptor (Gs-coupled):
- FSH binding increases the expression of ABP + aromatase
(CYP19) and production of growth factors + inhibins

55
Q

VIII. Hypothalamic-pituitary-gonadal axis
4. Make a schematic diagram for Hypothalamic-pituitary-gonadal axis

A
56
Q

VIII. Hypothalamic-pituitary-gonadal axis
5. Why is it important to have high intratubular [testosterone]?

A
57
Q

VIII. Hypothalamic-pituitary-gonadal axis
6A. What happen if there is Addition of external testosterone?

A
58
Q

IX. Further parts of the male reproductive tract
1. What are the features of spermaturation

A
59
Q

IX. Further parts of the male reproductive tract
2. What are the features of storage and emission?

A
60
Q

IX. Further parts of the male reproductive tract - Formation of semen
4A. What are the 3 organs involved in the production of semen?

A

1) Seminal vesicles
2) Prostate (DHT dependent)
3) Bulbourethral glands (Cowper)

61
Q

IX. Further parts of the male reproductive tract - Formation of semen
4B. How are seminal vesicles involved in the production of semen?

A
  • 65-70% of semen volume
  • Fructose (energy source)
  • Fibrinogen + semenogelins (coagulation of sperm)
  • Prostaglandins (immunomodulatory in female)
62
Q

IX. Further parts of the male reproductive tract - Formation of semen
4C. How is prostate involved in the production of semen?

A

Prostate (DHT dependent):
- 25-30% of semen volume
- Prostate specific antigen (PSA), fibrinolysin
- Citrate, Zn2+, spermine and phosphatase

63
Q

IX. Further parts of the male reproductive tract - Formation of semen
4D. How are Bulbourethral glands (Cowper) involved in the production of semen?

A
  • 3-5% of semen volume
  • Produces mucus, pre-ejaculate
    => Complete activation of sperm cells in female genital tract only! Capacitation
64
Q

IX. Further parts of the male reproductive tract - Formation of semen
5. What are important values in normal semen? (volume, pH,..)

A
  • Volume = >1,5mL
  • pH=7,2–8,0
  • 39 million spermatozoa/ejaculate (should not be any less than 15 million/μL)
  • More than 40% should show motilitly after 60 mins
  • More than 4% should show normal morphology
65
Q

X. Erectile function
1. What are the 2 states of erectile function?

A
  1. Flaccid state
  2. Erect state
66
Q

X. Erectile function
2. What happen in Flaccid state?

A
67
Q

X. Erectile function
3. What happen in Erect state?

A
68
Q

X. Erectile function
4A. What is the molecular mechanism of erection in Flaccid state?

A
69
Q

X. Erectile function
4B. In flaccid state, what does sympathetic nerve endings do?

A
70
Q

X. Erectile function
4C. In flaccid state, what is the role of Endothelial cell?

A
  • Endothelial cell: will produce endothelins + prostaglandins, which act on G-protein (Gq) and will have the same effects as α1 receptors
71
Q

X. Erectile function
5A. What is the molecular mechanism of erectile function in erect state?

A
72
Q

X. Erectile function - Erect state
5B. What type of control is erect state under?

A

PARA control

73
Q

X. Erectile function - Erect state
5C. In erect state, what is the role of PARA nerve endings?

A
74
Q

X. Erectile function - Erect state
5D. What is PDE5?

A

PDE5 is an anti-erection agent that is inhibited by sildenafil (Viagra)
- Viagra will inhibit PDE5 and thereby increase [cGMP] => dilation (erection)

75
Q

X. Erectile function - Erect state
5E. What is the role of Non-adrenergic/noncholinergic neurons in erect state?

A

Non-adrenergic/noncholinergic neurons also release VIP (Gs)
=> ↑cAMP
=> ↓[Ca2+]
=> SMC relaxation

76
Q

X. Erectile function - Erect state
5F. In erect state, What is the effect of ACh?

A
  • The released ACh can pre-synaptically inhibit the SYM nerves
  • ACH can also act on endothelial cells, cholinergic receptor (Gq) -> PLC -> ↑[Ca2+]IC
77
Q

X. Erectile function - Erect state
5G. In erect state, What is the role of Endothelial cells?

A

Endothelial cells express endothelial NO synthase (eNOS) – activated by Ca2+
=> produce NO
=> SMC relaxation

78
Q

XI. Reflex control
1. What are the steps of the male sex act?

A

The male sex act is divided into 3 steps: erection, emission, ejaculation

79
Q

XI. Reflex control
2. What are the 2 types of reflexes in male sex act?

A
80
Q

XI. Reflex control
3A. What are the 4 phases of erection?

A

1) Flaccidity
2) Full erection
3) Emission
4) Detumescence

81
Q

XI. Reflex control - Phases of erection
3B. What happen in phase 1: Flaccidity?

A
82
Q

XI. Reflex control - Phases of erection
3C. What happen in phase 2: Full erection?

A
83
Q

XI. Reflex control - Phases of erection
3D. What happen in phase 3: Emission?

A
84
Q

XI. Reflex control - Phases of erection
3E. What happen in phase 4: Detumescence?

A

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