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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
Q

Describe the mitotic division phase of Spermatogenesis *spermatocytogenesis)

A
  • 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
Q

Describe the meiosis phase of Spermatogenesis

A
  • 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
Q

Describe the spermiogenesis phase of Spermatogenesis

A
  • 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
Q

What are the three major hormonal factors that stimulate spermatogenesis

A

LH
FSH
GH

29
Q

What are the two main differences the male reproductive tract has

A
  • Continuous lumen from seminiferous tubule to the end of the male tract
  • Male tract connects to the distal urinary tract
30
Q

What role do parasympathetics play in erection

A
  • 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
Q

How does Viagra work

A
  • NO activates guanylyl cyclase to make cGMP

- cGMP prolongs the erection so viagra inhibits Type 5 phosphodiesterase which degrades cGMP to GMP

32
Q

What is the male sexual response of Emission

A

Movement of semen from the epididymis, vas deferens , seminal vesicles and prostate to the ejaculatory ducts

33
Q

What happens when there is a lack of testosterone (gonadal dysfunction) in the 2-3rd months of gestation vs 3rd trimester of pregnancy

A

2-3 months = ambiguity in male genitalia

3rd trimester = problems with testicular descent (cryptorchidism) and micropenis

34
Q

What happens when there is a lack of testosterone (gonadal dysfunction) in puberty vs post-pubery

A 
Puberty = poor secondary development and overall eunuchoid features
Post-Puberty = decreased libido, ED, low hair and energy, infertility
35
Q

What is Kallman’s Syndrome

A

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
Q

What is Klinefelter Syndrome

A

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
Q

What does Hyperprolactinemai do

A

suppresses FSH and LH secretion

GIGU Quiz 2 (16 decks)

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