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GIGU Quiz 2 > 12. Male Reproductive Physiology > Flashcards

12. Male Reproductive Physiology Flashcards

1
Q

What distinguishes gonadal sex and phenotypic sex

A

Gonadal- testes or ovaries

Phenotypic- physical characteristics of internal genital tract and external genitalia

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2
Q

What are the main gonadotropin hormones

A

FSH and LH

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3
Q

How do levels of FSH and LH compare in childhood and puberty/adulthood and senescence

A

Childhood- FSH > LH
Puberty/Adulthood- LH > FSH
Senescence- FSH > LH

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4
Q

What initiates puberty

A

Pulsatile secretion of GnRH which drives the pulsatile secretion of FSH and LH

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5
Q

What happens if a long-acting GnRH analogue is administered

A

Puberty is not initiated

-If a GnRH analogue is administered in intermittent pulses puberty is initiated and reproductive function is established

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6
Q

What are the main general functions of the testes, scrotum and epididymis

A

Testes- spermatogenesis and secretion of testosterone
Scrotum- lower temperature below body temperature
Epididymis- primary location for maturation and storage of sperm

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7
Q

What are the main general functions of the Vas deferens and the Prostate gland

A

Vas Deferens- storage for sperm, nourish sperm (fructose), seminal vesicles (adds 2/3 fluid)
Prostate Gland- secrete milky aqueous solution rich in citrate, calcium and enzymes

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8
Q

What makes up seminiferous tubules

A

Epithelium formed by the Sertoli cells with interspersed germ cells

  • Spermatogonia (immature) are in the periphery
  • Spermatozoa (mature) are near the lumen
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9
Q

What makes up the testis

A

80% seminiferous tubules

20% CT with Leydig cells

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10
Q

What is the general function of Sertoli cells

A

‘Nursing Cells’

  • Form tight junctions to control sperm environment
  • Provide nutrients to the sperm
  • Helps transport sperm through tubules into epididymis
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11
Q

What is the general function of Leydig cells

A

Synthesis and secretion of testosterone

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12
Q

What is the function of 17B-Hydroxysteroid in male physiology

A

-Converts androstenedione to testosterone

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13
Q

In the periphery what activates testosterone in target tissue

A

5a-reductase converts T to DHT

lack of enzyme results in ambiguous external genitalia

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14
Q

What is responsible for steroid synthesis in the testis

A

Leydig cells synthesize cholesterol de novo and store cholesterol as esters

  • generated via Hormone-Sensitive Lipase (HSL)
  • cholesterol is transferred via StAR
  • cholesterol converted to pregnenolone
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15
Q

How do males get estrogen

A
  • Aromatase (CYP19) converts testosterone to estradiol in sertoli cells
  • Most estrogen made in adipose tissue
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16
Q

What is the rate-limiting step in synthesis of testosterone

A

Conversion of cholesterol to pregnenolone by P450SCC

17
Q

How is testosterone concentrated in seminiferous tubules

A

binding to ABP

18
Q

What role does LH play in testosterone synthesis

A

Promotes pregnenolone synthesis via

  • increasing affinity of P450SCC for cholesterol
  • stimulate synthesis of P450SCC
19
Q

How does most of testosterone circulate

A

60% bound to sex hormone-binding globulin (SHBG)
38% bound to albumin
2% free

20
Q

What does DHT due embryologically

A

External Genitalia (penis prostate and scrotum)

21
Q

What are some anabolic actions of androgens

A
  • Stimulation of erythropoietin synthesis
  • Stimulation of sebaceous gland secretion
  • Stimulation of ABP synthesis
  • Nitrogen retention
22
Q

What is Benign Prostastic Hyperplasia (BPH)

A
  • Patients might have more DHT receptors on prostates but do not have more DHT in prostastic receptor
  • Patients have prostate peeing issues
23
Q

What are the intracellular mechanism of action of testosterone

A

cAMP-PKA pathway for both LH and FSH

FSH- uses pathway to synthesize ABP and aromatase

24
Q

What are the three stages of Spermatogenesis

A
  1. Mitotic divisions
  2. Meiotic divisions
  3. Spermiogenesis
25
Describe the mitotic division phase of Spermatogenesis *spermatocytogenesis)
- Proliferative phase - At puberty, mitotic cycles increase and spermatogonia or stem cells divide to produce daughter spermatogonia - After last division the resulting cells are called primary spermatocytes
26
Describe the meiosis phase of Spermatogenesis
- Production of the haploid gamete - Primary spermatocytes undergo two meiotic divisions - First division produces two secondary spermatocytes, each with a haploid number of duplicated chromosomes - Secondary spermatocytes enter second meiotic division, producing two spermatids, each with a haploid number of unduplicated chromosomes
27
Describe the spermiogenesis phase of Spermatogenesis
- Spermatids undergo spermiogenesis and mature into spermatozoa - Nuclear and cytoplasmic changes to produce mature spermatozoa - Ends in testis with release of spermatozoa from Sertoli cells
28
What are the three major hormonal factors that stimulate spermatogenesis
LH FSH GH
29
What are the two main differences the male reproductive tract has
- Continuous lumen from seminiferous tubule to the end of the male tract - Male tract connects to the distal urinary tract
30
What role do parasympathetics play in erection
- Innervates vascular SM of the helicine arteries that supply blood to the cavernous spaces release NO - Vasodilation allows blood to flow into spaces, causing engorgement and erection - Engorged tissue presses the veins against a noncompliant outer fascia, reducing venous drainage
31
How does Viagra work
- NO activates guanylyl cyclase to make cGMP | - cGMP prolongs the erection so viagra inhibits Type 5 phosphodiesterase which degrades cGMP to GMP
32
What is the male sexual response of Emission
Movement of semen from the epididymis, vas deferens , seminal vesicles and prostate to the ejaculatory ducts
33
What happens when there is a lack of testosterone (gonadal dysfunction) in the 2-3rd months of gestation vs 3rd trimester of pregnancy
2-3 months = ambiguity in male genitalia | 3rd trimester = problems with testicular descent (cryptorchidism) and micropenis
34
What happens when there is a lack of testosterone (gonadal dysfunction) in puberty vs post-pubery
``` Puberty = poor secondary development and overall eunuchoid features Post-Puberty = decreased libido, ED, low hair and energy, infertility ```
35
What is Kallman's Syndrome
Genetic disorder where GnRH neurons fail to migrate into the hypothalamus during embryological development - Delayed or absent puberty and an impaired sense of smell - Form of hypogonadotropic hypogonadism (SECONDARY)
36
What is Klinefelter Syndrome
Seminiferous tubular dysgenesis- male with an extra X chromosome - at puberty gonadotropins levels fail to induce normal testicular growth and spermatogenesis - low androgen production but high gonadotropins indicating PRIMARY HYPOGONADISM
37
What does Hyperprolactinemai do
suppresses FSH and LH secretion

GIGU Quiz 2 (16 decks)

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