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UROGENITAL > 12.2&3 MALE REPRODUCTION - SPERM PRODUCTION, EJACULATION, TESTOSTERONE > Flashcards

12.2&3 MALE REPRODUCTION - SPERM PRODUCTION, EJACULATION, TESTOSTERONE Flashcards

1
Q

3 TIERS of REPRODUCTIVE AXIS in MALES

A

HYPOTHALAMUS

PITUITARY (ANTERIOR)
- LH, FSH

TESTIS
-TESTOSTERONE and production spermatozoa

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2
Q

in HPT AXIS what is the role of the HYPOTHALAMUS

A

RELEASE GnRH (GONADOTROPHIN RELEASING HORMONE)

into hypothalamohypophysial shunt (portal system of blood vessels)

to PITUITARY

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3
Q

in HPT AXIS what is the role of the ANTERIOR PITUITARY GLAND

A

GONADOTROPES SECRETE LH and FSH
in response to GnRH (hypothalamus)

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4
Q

in HPT AXIS what is the role of the LEYDIG CELLS

A

in INTERSTITIUM of TESTIS

  • STIMULATED by LH to produce TESTOSTERONE
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5
Q

in HPT AXIS what is the role of the SERTOLI CELLS

A

STIMULATED by FSH to SUPPORT SPERMATOGENESIS in the seminiferous epithelium (surround spermatogonia)

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6
Q

what is STIMULATED by LH in males

A

TESTOSTERONE PRODUCTION in LEYDIG CELLS (has LH RECEPTORS)

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7
Q

what is STIMULATED by FSH in males

A

SUPPORT of SPERMATOGENESIS by SERTOLI CELLS

and synthesise ABP (protein)

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8
Q

when LH BINDS to LH RECEPTORS on LEYDIG CELLS what is STIMULATED in order to produce Testosterone

A

ADENYLATE-CYCLASE

  • activates cAMP
  • protein kinases
  • cholesterol esterases
  • free cholesterol
    (pregnenolone)
    testosterone
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9
Q

ORIGINS of TESTOSTERONE

A

95% from TESTIS

5% from other sources including:
- ADRENAL CORTEX
- ADIPOSE TISSUE
- SKIN
- BRAIN
- MUSCLE

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10
Q

FUNCTIONS of TESTOSTERONE in FOETAL LIFE

A
  • SEX DIFFERENTIATION
  • DEVELOPMENT of ACCESSORY SEX ORGANS
  • DESCENT of TESTIS

(foetal leydig cells regress after birth)

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11
Q

FUNCTIONS of TESTOSTERONE in PUBERTY

A
  • DEVELOPMENT of SECONDARY SEXUAL CHARACTERISTICS including:

change in BRAIN, VOICE
Increase HEIGHT, MUSCLE mass, FACIAL hair
Production of SPERM and SEXUAL FUNCTION

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12
Q

97% of TESTOSTERONE is…

A

PROTEIN-BOUND

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13
Q

MAJORITY of TESTOSTERONE is BOUND to

A

SEX HORMONE-BINDING GLOBULIN (SHBG)
- strongly
- INACTIVE

some bound to ALBUMIN (less strongly, some activity)

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14
Q

which TESTOSTERONE is the MOST ACTIVE but difficult to measure

A

FREE TESTOSTERONE (not protein-bound)

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15
Q

TESTOSTERONE bound to SHBG are

A

INACTIVE

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16
Q

how to MEASURE BIOAVAILABLE TESTOSTERONE

A
  • measure FREE fraction and those BOUND to ALBUMIN
  • using VERMEULEN EQUATION, can be estimated from testosterone, SHBG and albumin concs
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17
Q

ACTIVTY of TESTOSTERONE is mostly due to its ACTIVE FORM called

A

DIHYDROTESTOSTERONE (DHT)

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18
Q

what is TESTOSTERONE CONVERTED to

A

DIHYDROTESTOSTERONE (DHT)

  • ACTIVE FORM
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19
Q

how is TESTOSTERONE CONVERTED to DHT (using what)

A

ENZYME 5-ALPHA-REDUCTASE

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20
Q

5-ALPHA-REDUCTASE may be

A
  • Deficient - leading to lack of masculinisation
  • Target for drugs in BPH (Benign Prostatic Hyperplasia)
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21
Q

where does SPERMATOGENESIS happen

A

SEMINIFEROUS TUBULES of TESTES

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22
Q

SPERMATOGENESIS is STIMULATED by

A

ANTERIOR PITUITARY GONADOTROPHIC hormones:
- LH and FSH

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23
Q

SPERMATOGENESIS occurs at average age

A

13

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24
Q

SEMINIFEROUS TUBULES SUPPORTING cells:

A
  • SUSTENTACULAR CELLS of the basement membrane
  • SERTOLI CELLS
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25
Q

GERMINAL ELEMENTS of SEMINIFEROUS TUBULES comprise of EPITHELIAL CELLS including:

A
  • Slowly dividing PRIMITIVE STEM CELL population
  • Rapidly proliferating SPERMATOGONIA
  • SPERMATOCYTES undergoing Meiosis
  • metamorphosing SPERMATIDS
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26
Q

INNERMOST LAYER of SEMINIFEROUS TUBULE consists of 2 CELLS

A
  • SPERMATOGONIA (primitive germ cells)
  • SERTOLI CELLS (Surround germ cells, offering STRUCTURAL SUPPORT)
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27
Q

through the FORMATION and BREAKDOWN of GAP JUNCTIONS, SERTOLI CELLS…

A

GUIDE GERM SPERM CELLS TOWARDS LUMEN

the availability of NUTRIENTS TO GERM CELLS is CONTROLLED by the SERTOLI CELLS through these GAP JUNCTIONS
through restriction of substances and the blockage of paracellular diffusion

28
Q

the FORMATION of TIGHT JUNCTIONS serves as the PHYSICAL BASIS for the…

A

BLOOD-TESTIS BARRIER

  • creating microenvironment that is SPECIALISED and IMMUNOLOGICALLY SAFE

Blood-Testis Barrier: formed by the tight junctions between Sertoli cells - creates a barrier, allows environment (microenvironment) to be safe for sperm.
Prevents escape of membrane antigens of differentiating sperm into blood which would activate immune system.
Prevents entry of toxins into seminiferous tubules
Helps maintain unique chemical composition of s.f fluid

29
Q

which RECEPTORS do SERTOLI CELLS EXPRESS

A
  • ANDROGEN RECEPTORS for RECOGNITION of TESTOSTERONE (essential in progression of spermatogenesis)
  • FSH RECEPTORS for RECOGNITION of FSH (essential for maximal sperm production)
30
Q

during EMBRYOGENESIS PRIMORDIAL GERM CELLS MIGRATE into..

A

TESTES
become IMMATURE germ cells - SPERMATOGONIA

31
Q

what happens to SPERMATOGONIA from PUBERTY

A

undergo MITOSIS and continually proliferate and differentiate and develop to form SPERM

32
Q

steps in SPERMATOGENESIS

A
  • SPERMATOGONIA MIGRATE among SERTOLI CELLS TOWARDS CENTRAL LUMEN of SEMINIFEROUS TUBULE
  • SPERMATOGONIA progressively modified and ENLARGED (MITOSIS) to form Large PRIMARY SPERMATOCYTES
  • Primary Spermatocytes undergo MEIOSIS I to form 2 SECONDARY SPERMATOCYTES
  • secondary spermatocytes DIVIDE (MEIOSIS II) to form SPERMATIDS
  • modified to become SPERMATOZOA
33
Q

Approx how long does SPERMATOGENESIS take

A

64 days

34
Q

what is SPERMATOGENESIS

A

PRODUCTION of MATURE SPERMATOZOA

35
Q

what is SPERMIOGENESIS

A

CONVERSION of SPERMATIDS INTO SPERMATOZOA

36
Q

what is SPERMIATION

A

RELEASE of SPERMATOZOA INTO LUMEN

37
Q

what is CAPACITATION

A

FINAL MATURATION of SPERMATOZOA in FEMALE GENITAL TRACT

(conditioning process to liberate acrosome)

38
Q

what is the CONVERSION of SPERMATIDS into SPERMATOZOA called

A

SPERMIOGENESIS

39
Q

what is the RELEASE of SPERMATOZOA into the LUMEN called

A

SPERMIATION

40
Q

before DIFFERENTIATING and ELONGATING into Spermatozoa, SPERMATIDS still have usual CHARACTERISTICS of

A

EPITHELIOID CELLS

41
Q

on the outside of the ANTERIOR TWO THIRDS of the HEAD of the SPERMATOZOON what is there

A

THICK CAP - ACROSOME

42
Q

ACROSOME of SPERMATOZOA HEAD is mainly FORMED from the..

A

GOLGI APPARATUS

43
Q

what does ACROSOME of SPERMATOZOA HEAD contain

A

ENZYMES
- help sperm to enter ovum

(eg Hyaluronidase and tubal mucosal enzymes for corona radiata,
acrosin (proteolytic) esterases and neuraminidase for zona pellucida)

44
Q

both TESTES produce up to how much sperm a day

A

120 MILLION per DAY

45
Q

where is MOST of the SPERM STORED

A

VAS DEFERENS

(small amount in epididymis)

46
Q

normal MOTILE, FERTILE SPERM are capable of FLAGELLATED MOVEMENT through the fluid liquid medium at what VELOCITY

A

1-4 mm/min

47
Q

POST ejaculate MAXIMAL LIFE SPAM of SPERM is

A

24-48 HOURS at body temperature

(although can live for many weeks in male genital ducts)

48
Q

role of TESTOSTERONE in SPERMATOGENESIS

A

GROWTH and DIVISION of GERM CELLS

49
Q

role of LH in SPERMATOGENESIS

A

STIMULATES LEYDIG CELLS to SECRETE TESTOSTERONE

50
Q

role of FSH in SPERMATOGENESIS

A

STIMULATES SERTOLI CELLS necessary for the CONVERSION of SPERMATIDS to SPERMATOZOA (SPERMIOGENESIS)

51
Q

how are OESTROGENS FORMED and what are they ESSENTIAL for in SPERMATOGENESIS

A
  • formed FROM TESTOSTERONE by SERTOLI CELLS when stimulated by FSH
    (FSH -> SCs -> Testosterone
    -> Oestrogens)
  • essential for SPERMIOGENESIS (SPERMATIDS TO SPERMATOZOA)
52
Q

Role of GROWTH HORMONE in SPERMATOGENESIS

A
  • CONTROLS BACKGROUND METABOLIC FUNCTIONS of the TESTES
  • PROMOTES EARLY DIVISION of SPERMATOGONIA
53
Q

what controls background METABOLIC FUNCTIONS of the TESTES and promotes EARLY DIVISION of the SPERMATOGONIA

A

GROWTH HORMONE

54
Q

what INHIBITS SPERMATOGENESIS

A

INCREASE in TEMPERATURE

(internal temp of scrotal sac is 2-3 degrees lower than body temp)

55
Q

how is REGULATION of SCROTAL TESTES TEMPERATURE brought about

A

CONTRACTION or RELAXATION of DARTOS and CREMASTER MUSCLES of the scrotum

56
Q

what can cause DEGENERATION of the SEMINIFEROUS TUBULES

A

INFECTIONS such as MUMPS

57
Q

Where does SEMINAL FLUID come from

A

ACCESSORY SEX GLANDS,
PROSTATE (nutrients, enzymes, PSA)
SEMINAL VESICLES (mucoid material - fructose, citric acid, nutrients, prostaglandins, fibrinogens)
BULBOURETHRAL glands (mucus)

58
Q

average VOLUME of EJACULATE and what does it contain

A

3 mL

  • SPERMATOZOA
    (less than 1%) (100 million/mL)
  • SEMINAL FLUID
59
Q

SEMINAL FLUID is unusual because of its HIGH CONCENTRATIONS of

A
  • POTASSIUM
  • ZINC
  • CITRIC ACID
    -FRUCTOSE
  • PHOSPHORYLCHOLINE
  • SPERMINE
  • FREE AMINO ACIDS
  • PROSTAGLANDINS
  • ENZYMES (acid phosphatase, diamine oxidase, beta-glucuronidase, lactate dehydrogenase, alpha-amylase, PSA, seminal proteinase)
60
Q

process of SEXUAL AROUSAL

A
  • sexual arousal
    LIBIDO (requires TESTOSERONE)
  • ERECTION
    increased blood flow into penile corpus cavernosa
  • EMISSION
    deposition of sperm into proximal part of urethra
  • EJACULATION
    forceful discharge of semen through urethra
  • DETUMESCENCE / RELAXATIN
61
Q

reflex reaction of EJACULATION is TRIGGERED by

A

EMISSION
- entry of SEMEN from the prostatic urethra into the BULBOUS URETHRA

62
Q

EJACULATION is dependent on what REFLEX

A

SPINAL CORD REFLEX
- with CEREBRAL CONTROL

AFFERENT (sensory)
- SACRAL SPINAL CORD S2-S4

EFFECT (somatic motor neurons)
- via PUDENDAL NERVE

63
Q

AFFERENT (sensory) reflex of EJACULATION is from which SPINAL CORDS

A

S2-S4 (SACRAL)

64
Q

EFFERENT (somatic motor neurons) reflex of EJACULATION is via which NERVE

A

PUDENDAL NERVE

65
Q

what MUSCLE CONTRACTIONS propel the semen via the urethra through the external meatus (EJACULATION)

A
  • RHYTHMIC CONTRACTIONS of the STRIATED MUSCLES of the PERINEAL AREA:
    Muscles of PELVIC FLOOR, ISCHIOCAVERNOSUS, BULBOSPONGIOSUS muscles
  • SPASMODIC CONTRACTIONS of the muscles of the HIPS and ANAL SPHINCTER
    (spasm, sudden involuntary)

UROGENITAL (19 decks)

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