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Physiology 2 > Reproduction: Spermatogenesis > Flashcards

Reproduction: Spermatogenesis Flashcards

1
Q

What is the optimal temperature for sperm production in the testes?

A

1.5-2.5°C below body temperature

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2
Q

What is the normal volume of the testes?

A

Between 15-25 ml

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3
Q

How is an orchidometer used to examine the size/volume of the testes?

A
  • Orchidometer has different sized beads each with known volume
  • Doctor will palpate a testicle as well as each of the beads on the orchidometer until they feel the same weight within the doctors hands
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4
Q

What structure are the testes mainly made up of?

A

Mainly made up of semineferous tubules (90% of each testicle made up of semineferous tubule).

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5
Q

What are some characteristics of the semineferous tubules?

A
  • 600m worth of semineferous tubules within each testicle
  • All of the tubules lead to the rete testis which connect to the epididymis which is connected to the vas deferens.
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6
Q

Within the walls of the semineferous tubule there are spermatogonia. What are spermatogonia?

A

Undiffererentiated germ cells on basement membrane that are able to undergo mitosis and produce more spermatogonia or under meiosis and differentiate into primary spermatocytes

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7
Q

What does the fact that the spermatogonia can undergo mitosis mean for sperm production in men?

A

It means that unlike women men can always continue to produce sperm so remain fertile trhoughout their lifetime

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8
Q

Briefly explain the process of how spermatogonia become mature sperm cells

A
  • Spermatogonia go through mitosis to form primary spermatocyte
  • Primary spermatocyte goes through meiosis I to form secondary spermatocyte
  • Secondary spermatocyte goes through mitosis II to from spermatids
  • Spermatids then form mature sperm cells
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9
Q

Within the semineferous tubules there are columns of sertoli cells what are the spaces between these columns of sertoli cells called?

A

Adluminal compartment

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10
Q

What cells/substances are within the adluminal compartment?

A
  • Secretions from the sertoli cells
  • Developing sperm cells (spermatogonia, primary and secondary spermatocytes)
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11
Q

What structure do the adluminal compartments forms?

A

They form the blood-testes barrier

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12
Q

Within the testes there are spaces between the semineferous tubules. What are these spaces filled with?

A
  • Blood and lymphatic vessels
  • Leydig cells
  • Interstitial fluid.
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13
Q

What are the 3 types of spermatogonia?

A
  • Type A dark spermatogonia
  • Type A pale spermatogonia
  • Type B spermatogonia
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14
Q

Explain how each of the 3 types of spermatogonia are formed?

A
  • Type A dark spermatogonia formed from Type A dark spermatogonia undergoing mitosis
  • Type A pale spermatogonia formed from the differentitaion of Type A dark seromatogonia
  • Type B spermatogonia formed from Type A pale spermatogonia undergoing mitosis
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15
Q

Once the type B spermatogonia are formed what occurs to them and what is formed as a result?

A
  • Type B spermatogonia move from basement membrane into the adluminal compartment and duplicate their DNA
  • This causes formation of diploid primary spermatocyte
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16
Q

Once the spermatids are formed from the secondary spermatocytes where do they move into within the semineferous tubule?

A
  • Once spermatids are formed they migrate from adluminal compartment towards the lumen of the semineferous tubule
17
Q

What is Spermiogenesis?

A

The differentiation of the spermatids into the spermatozoa as they move into the lumen of the semineferous tubule

18
Q

What changes occur to the spermatids as they differentitate into spermatozoa?

A
  • Loss of cytoplasm
  • Elongation
  • Growth of tail and acrosome
  • Movement of cellular contents
19
Q

What does it mean when it says that the meiotic divisions of spermatogenesis are “incomplete?”

A

It means that each of the cells produced as a result of meiotic division are connected to each other via a cytoplasmic bridge which creates a synctium

20
Q

What does the production of synctia during spermatogenesis mean for the cells cause its formation?

A

It means that each of the cells produced during the meiotic division sof spermatogenesis that form the synctia can develop together

21
Q

Explain the effect LH has on spermatogenesis

A
  • LH secreted from anterior pituitary binds to LH receptors on Leydig cells between semineferous tubules
  • This causes cholesterol to be converted into androgens (mainly testosterone) by the leydig cells
  • Testosterone then migrates to Sertoli cells within semineferous tubules
  • This stimulates Sertoli cells to produce secretions that help/nuture developing spermatozoa
22
Q

Explain the effect FSH can has on spermatogenesis

A
  • FSH released from anterior pituitary will bind to FSH receptors on sertoli cells present within tight junctions of semineferous tubules
  • Binding of FSH to Sertoli cells allows for them to stay alive/be maintained as Sertoli cells need FSH to survive
  • Binding of FSH to sertoli cells also causes aromatase to convert androgens present in Sertoli cells to Oestrogens
23
Q

What is testicular atrophy?

A

Condition is which the testes diminish in size and may lose function

24
Q

How do anabolic steroids result in testicular atrophy?

A
  • Anabolic steroids contain both natural and synthetic androgens
  • These androgens produce negative feedback on hypothalamus and anterior pituitary which result in reduced secretion of GnRH, FSH and LH
  • Reduced LH secretion leads to reduced Sertoli cell function, Developing spermatogonia less well nutured so less are produced.
  • Reduced FSH secretion leads to reduction in no. of Sertoli cells present within semineferous tubules
  • Both of these effects result in testicular atrophy
25
Q

Explain how the parasympathetic nervous sytem contributes to the production of an erection

A
  • Parasympathetic nervous system causes vasodilation of the arteries of corpus cavernosum
  • Also causes vasoconstriction of the veins of the corpus cavernosum
  • This causes tissue of corpus carvenosum/corpus spongiosum to fill with blood and swell producing erection
26
Q

How does swelling of corpus cavernosum/ corpus spongiosum result in maintainance of an erection?

A
  • Swelling leads to compression of the penile veins/venules which means more blood is able to stay within the penile tissue and maintain swelled state of corpus tissue
27
Q

Explain how the sympathetic nervous system contributes to ejaculation?

A
  • Sympathetic nervous system causes smooth muscle contraction in the epididymis and vas deferens
  • This causes sperm to move from the epididymis into the penile urethra
28
Q

What two nervous systems are involved in the evacuation of the ejaculate from the penile urethra?

A
  • Sympathetic nervous system
  • Somatic nervous system
29
Q

Apart from sperm cells ejaculate contains seminal fluid. What is seminal fluid?

A
  • Fluid in which the sperm cells swim in
  • Contains secretions from seminal vesicles, prostate and bulbo-urethral gland
30
Q

How do secretions from bulbo-urethral gland contribute to production of seminal fluid?

A
  • Bulbo-urethral gland secretes fluid prior to ejaculation which helps to lubricate the urethra for spermatozoa to pass through.
  • This fluid neutralises traces of acidic urine within the urethra
31
Q

How do secretions from seminal vesicles contribute to production of seminal fluid?

A
  • Secretes fluid into ampulla of vas deferens as sperm cells move through it
  • Secretions contain proteins, enzymes, fructose and and prostaglandins
32
Q

What role does the fructose within the secretions of seminal vesicles play in the production of seminal fluid?

A

Fructose provides energy source for sperm cells allowing them to travel through urethra

33
Q

How do secretions from the prostate contribute to production of seminal fluid?

A
  • Secretes milky or white fluid
  • Secretions contain proteolytic enzymes, prostatic acid phosphatase and prostate-specific antigen
  • Alos has high zinc concentration
34
Q

Why do the secretions from the prostate have a high zinc concentration?

A

Zinc thought to be antibacterial

35
Q

Proteolytic enzymes, prostatic acid phosphatase and prostate-specific antigen are involved in liquefaction of the ejaculate. What does this mean?

A

Means over time the ejaculate goes from viscous to more runny and liquid-like

36
Q

Why does the ejaculate go through liquefaction?

A
  • It occurs so that the sperm present within the ejaculate don’t move around too much until they reach the vagina/cervix
  • So ejculate starts off viscous to prevent movement of sperm but needs to become more liquid-like to then allow sperm to move freely
37
Q

What are some of the criteria for a normal sperm sample?

A
  • Volume 1.5 – 6.0 ml
  • Liquefaction before 30 minutes
  • Motility > 40%
  • Normal morphology > 4%

Physiology 2 (29 decks)

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