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Endocrinology > TBL7 Male Sexual Repro > Flashcards

TBL7 Male Sexual Repro Flashcards

1
Q

The ______ in the testes is where all the seminiferous tubules are collected.

A

rete testis

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2
Q

Spermatozoa mature in the __________ of the testis. (numerous coiled tubules)

A

epididymis

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3
Q

Why is spermatozoa produced continually throughout a male’s reproductive life?

A

Not all the spermatogonia are activated together - there is always a pool of spermatogonia which remains available for subsequent spermatogenic cycles throughout life.

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4
Q

The initial germ cells are (haploid/diploid).

_________ then undergo the first meiotic division to produce haploid _______, which then undergo the second meiotic division to transform into spermatids.

A

diploid

First meiotic division: Primary spermatocytes (diploid) –> Secondary spermatocytes (haploid)

Second meiotic division: Secondary spermatocytes –> Spermatids

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5
Q

______ cells lie within the seminiferous tubules. It synthesises FSH and androgen receptors, and responds to FSH to produce molecules like inhibin.

A

Sertoli cells

  • within the seminiferous tubules
  • synthesise FSH and androgen receptors
  • responds to FSH
  • associated with spermatogenesis
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6
Q

_______ cells in the testis lie outside the seminiferous tubules in the interstitial spaces.

A

Leydig cells

  • lie outside seminiferous tubules
  • synthesise LH receptors
  • produce testosterone in response to LH
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7
Q

The tubular lumen of a seminiferous tubule is full of _________.

A

inactive mature spermatozoa (matures towards the lumen)

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8
Q

Sertoli cells are surrounded by spermatogonia-containing fluid along with primary and secondary spermatocytes.
Sertoli cells are linked together by _________, in which secondary spermatocytes will push their way through.

A

Sertoli cells linked together by tight junctions
- secondary spermatocytes squeeze their way through to become enclosed by the Sertoli cells and undergo transformation under the influence of molecules produced by the Sertoli cells to form spermatozoa

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9
Q

Androgens are _____ hormones produced by 2 organs:
1.
2.

A

Androgens are steroid hormones.
Produced by:
1. Adrenal cortex
2. Gonads (Testis)

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10
Q

Precursor of androgen is

A

cholesterol –> pregnenolene –> progesterone —> Androstenedione

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11
Q

In the gonads, androstenedione is converted to testosterone, and both are converted to ________ via in males and females, which is then converted to the biologically active ________.
In males, some of the testosterone is converted to ________.

A

Androstenedione –> testosterone –> oestrogen –> 17B-oestradiol

testosterone –> dihydrotestosterone (more potent androgen)

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12
Q

Testosterone can be converted to either DHT or oestrogens like 17B-oestradiol.

What type of reaction and what enzyme?

A

Testosterone to DHT:

  • Reduction
  • By 5a-reductase

Testosterone to oestrogen:

  • Aromatisation
  • by enzyme aromatase
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13
Q

Testosterone and DHT are transported in the BLOOD via ________ protein.

A

Sex hormone-binding globulin (SHBG)

Albumin

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14
Q

Androgens in the SEMINIFEROUS fluid is bound by _______.

A

Androgen-binding globulin (ABG)

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15
Q

Importance of androgens in foetal development

A
  1. Development of male genitalia
  2. Stimulates foetal growth
  3. Male behaviour in CNSS
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16
Q

Importance of androgens in adults

A
  1. Spermatogenesis
  2. Growth and development of male genitalia
  3. Sexual characteristics
  4. PROTEIN ANABOLISM
  5. Behavioural CNS effects
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17
Q

Note: Some androgenic effects are mediated by the conversion of testosterone to oestrogen!

A

-

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18
Q

Androgens bind to (intracellular/membrane) receptors.

A

intracellular receptors

  • forming androgen-receptor complex
  • stimulates synthesis of new proteins
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19
Q

Hypothalamo-pituitary-gonadal axis:

Hypothalamus secretes _______.

________ pituitary gland secretes ____.

A

Hypothalamus: Gonadotrophin-releasing hormone (GnRH)

Anterior pituitary gland: LH and FSH

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20
Q

LH acts on ________ cells to produce testosterone.

FSH acts on _______ cells to initiate spermatogenesis

A

LH –> Leydig cells –> testosterone

FSH –> Sertoli cells to initiate spermatogenesis (produce inhibin)

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21
Q

The main stimulus for the penis is ______.

A

tactile

- due to stretch receptors along the penis which can be stimulated

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22
Q

Main control over penile erection is via the __________.

A

limbic system in the brain

  • thoughts, visual stimuli can activate pathway down the spinal cord to cause penile erection
  • send efferent signals down
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23
Q

There are 3 efferent pathways involved in penile erection.

  1. Parasympathetic pathway
  2. Somatic pathway
  3. Sympathetic pathway
A
  1. Parasympathetic pathway via the pelvic nerve (main) to promote erection
  2. Somatic pathway via the pudendal nerve to promote erection
  3. Sympathetic pathway via the hypogastric nerve to depress erection
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24
Q

Penile erection is the (relaxation/contraction) of vascular smooth muscles.

A

Penile erection:

  • Relaxation of vascular smooth muscles
  • To dilate cavernous arteries in the corpus cavernosa (to increase blood flow)
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25
Q

__________ is the main penile tissue surrounding the urethra and prevents it from collapsing during increased arterial pressure from penile erection.

A

Corpus spongiosum

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26
Q

__________ lies outside the corpus spongiosum and contains the blood flow to the penis.

Blood enters via the _____ artery and leaves via the ____ vein.

A

Corpus cavernosa

Blood enters via pudendal artery and leaves via dorsal vein.

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27
Q

________ is a phosphodiesterase inhibitor, preventing cGMP from being broken down.
=> maintains vasodilatation and hence penile erection

A

Viagra

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28
Q

The bulk of seminal fluid comes from the accessory sex glands -

A

Seminal vesicles, prostate gland, bulbourethral glands

29
Q

Ejaculation is under the control of _________ nervous system, which causes the (relaxation/contraction) of smooth muscle of the vas deferens.

A

Ejaculation:

  • Sympathetic control
  • Contraction of smooth muscle of vas deferens
30
Q

On ejaculation, the efferent ductules contract and the spermatozoa contained in the ejaculate is passed into the _________.

A

prostatic urethra

31
Q

Testosterone is clinically used as a (anabolic/catabolic) steroid to increase lean body mass and muscle size and strength.

A

anabolic steroid (stimulates protein synthesis and bone formation)

32
Q

If pituitary testicular function is absent, will administering testosterone alone restore fertility?

A

No. Treatment requires LH and FSH replacement to stimulate both the Leydig cells to produce testosterone and the Sertoli cells that are also involved in spermatogenesis.

33
Q

Kallmann syndrome is associated with _________ and _______.

A

Kallmann syndrome:

  1. low GnRH levels
  2. anosmia (unable to smell)

=> Olfactory bulb cannot develop normally, so GnRH cannot migrate to the hypothalamus

34
Q

In Kallmann syndrome, patients are usually (taller/shorter) than usual.

A

taller than normal (lack of androgens prevents epiphysis of long bones from fusing)

35
Q

___________ (XXY) is a congenital primary gonadal disease that is due to an extra X chromosome, causing the testes to fail to produce androgens.

A

Klinefelter syndrome

36
Q

In patients with __________ deficiency, testosterone cannot be converted to the more potent DHT androgen, so there are no effects on Sertoli cells to cause spermatogenesis.

A

5a-reductase deficiency

congenital primary gonadal disease

37
Q

Testicular torsion refers to the rotating of the testis which twists the __________ that brings blood to the scrotum, resulting in reduced blood flow.

A

Testicular torsion: Rotating of the testis which twists the spermatic cord
=> reduced blood flow

38
Q

High _______ levels are associated with the inhibition of the hypothalamo-pituitary-gonadal axis, causing low LH and FSH.

A

Prolactin (inhibits GnRH release from the hypothalamus)

39
Q

Clinical features of hypogonadism:

A
  • Loss of libido
  • Impotence
  • Small testes (lack of stimulation)
  • Decreased muscle bulk
  • Osteoporosis
40
Q

For patients with hyperprolactinaemia which causes hypogonadism, ________ can be used to block the production of prolactin from the tumour.

A

dopamine agonists like bromocriptine or cabergoline

=> dopamine inhibits prolactin secretion

41
Q

When men age, they develop an enlarged prostate that can give rise to lower urinary tract symptoms (LUTS) and bladder outflow obstruction. This condition is known as __________.

A

Benign Prostatic Hyperplasia (BPH)

- Due to the increase in the number of cells, not the size of cells

42
Q

How does an enlarged prostate (in BPH) lead to LUTS and bladder outflow obstruction?

A

When the prostate enlarges, it compresses the urethra => Bladder needs to work harder to pump urine out => Detrusor muscle hypertrophy

43
Q

BPH most commonly occurs in ________ zone of the prostate.

A

transition zone

- surrounds part of the urethra

44
Q

LUTS may be divided into ______ and ______ symptoms.

A

LUTS:

  1. Voiding symptoms (Obstruction to urine flow)
    - Slow urinary flow
    - Straining
    - Terminal dribbling
    - Incomplete emptying
  2. Storage symptoms (Abnormal bladder function)
    - Urinary urgency
    - Nocturia
    - Incontinence
45
Q

PSA is a _______ protein secreted by ________ cells of the prostate into the lumen of the duct, used to find prostate cancer and BPH.

A

PSA:

  • Kallikrein protein
  • Secreted by epithelial cells of the prostate
  • Into the lumen of the duct (Discharged into the urethra)
46
Q

Under normal circumstances, PSA (will/will not) be detected by the blood as it is prevented by the ________ of the prostate from leaving the cells by any other route.

A

PSA:
- will not be detected in the blood under normal circumstances
- protected by the basal lamina from leaving
=> Prostate damage can result in PSA leakage into the bloodstream measured by serum immunoassay

47
Q

The pharmacotherapy for bladder obstruction (2 types of drugs):

A
  1. 5a-reductase inhibitors
    - prevent conversion of testosterone to DHT
    => size reduction of prostate gland
  2. a1-adrenoreceptor antagonists
    - leads to smooth muscle relaxation at the bladder neck and prostate
    => symptomatic relief (not treating cause)
48
Q

The surgical relief of bladder obstruction is _______.

A

Transurethral resection of the prostate (TURP)

- Hot wire loop allows for resection of enlarged prostate tissue, creating a cavity

49
Q

Any bleeding in TURP is stopped with _______.

A

diathermy

50
Q

Men tend to be ________ after TURP, so it is usually carried out for older men who have finished with family planning.

A

infertile (Cut out prostate)

51
Q

Most malignant neoplasms of the prostate gland are _________, arising in the _______ zones.

A

Most malignant neoplasms of the prostate gland are adenocarcinomas (glandular in origin), arising in the peripheral zones.

52
Q

Histological diagnosis for prostate cancer is made with a _________.

A

transrectal ultrasound-guided prostate biopsy (TRUS)

53
Q

The tumour (prostate cancer) can be graded using 2 systems.

A

TNM system

Gleason grading system (histological system based on gland architecture and degree of differentiation)

54
Q

Advanced prostatic cancer shows features of __________ or __________.

A

Advanced prostatic cancer:

  • Extraprostatic extension
  • Seminal vesicle invasion
  • Lymph node involvement
  • Metastatic prostate cancers
55
Q

Since prostate growth is androgen-dependent, the principle of management for advanced prostate cancer is to treat palliatively with ____________ therapy.

A

androgen deprivation therapy

56
Q

Androgen deprivation therapy involves the use of _______ analogues.

A

LHRH analogues

(e. g. goserelin)
- causes overstimulation of pituitary gland and overproduction of testosterone, which reduces LHRH via negative feedback

57
Q

Kidneys arise from the ____________.

A

intermediate mesoderm

58
Q

Development of the kidneys passes through 3 phases

A
  1. Pronephros (cervical region)
  2. Mesonephros (thoracolumbar region)
  3. Metanephros (sacral region)
59
Q

The mesonephros (during kidney development) gives rise to the _______ duct.

A

Mesonephric duct/Wolffian duct

  • gives rise to reproductive tract and ureters in males
  • ureters in females
60
Q

The caudal tip of the mesonephric duct gives rise to the __________.

A

ureteric bud

61
Q

The Y chromosome contains the ____ gene. Protein product of this gene is the _______, which is a transcription factor initiating a cascade of downstream genes to determine the fate of rudimentary sexual organs.

A

SRY gene

Protein product: testis-determining factor

(presence of TDF - male development; absence of TDF - female development)

62
Q

Early in development, the embryo has the full complement of tissues and tubes to develop as a male or female.
The ______ duct gives rise to male reproductive tract.

The ______ duct gives rise to female reproductive tract.

A

Wolffian duct/mesonephric duct - male reproductive tract

Mullerian/paramesonephric duct - female reproductive tract

Set of tubes that remain depends on whether the gonads turn into testes or ovaries

63
Q

The __________ is the precursor to gonads and is triggered to differentiate into testis or ovary on the signal __________ from the yolk sac.

A

genital ridge (precursor to gonads)

triggered to differentiate on signal from germ cell migration from yolk sac

64
Q

In males, the SRY gene activates the _____ transcription factor, which upregulates the expression of MIS, FGF9 and SF1 to stimulate the differentiation of ______ and ______ cells.

A

SRY gene => SOX9 transcription factor

=> Sertoli and Leydig cells

65
Q

________ produced by Sertoli cells causes the regression of the Mullerian ducts.

A

MIS (AMH)

66
Q

________ produced by the Leydig cells mediate virilisation of mesonephric ducts to form male genital ducts.

A

Testosterone

67
Q

Except for the __________ and _________, the Wolffian ducts persist to form the main genital ducts.

A

utriculus prostaticus and appendix epididymus

- arise from the remnant of the regressed Mullerian ducts

68
Q

The __________ attaches the testis and mesonephros to the posterior abdominal wall.

A

urogenital mesentery

Endocrinology (7 decks)

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