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Repro > Week 7.0 - Coitis and fertilisation > Flashcards

Week 7.0 - Coitis and fertilisation Flashcards

1
Q

How long does it take for spermatogonia to mature into spermatozoa?

A

-upto 74 days (50 in testis 12-24 in epididymis)

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2
Q

When does spermatogenesis begin/end?

A

-From puberty until death

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3
Q

How many of the sperm produced per day become viable sperm?

A

-50%

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4
Q

Does production of sperm stay the same throughout life?

A

-Decreases in quantity and quality with age

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5
Q

Which hormone acts on the leydig cells? What is the result of this?

A
  • LH

- Production of testosterone

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6
Q

Which hormone acts on the sertoli cells? What is the result of this?

A
  • FSH
  • Antigen binding protein production leading to the concentration of testosterone in luminal fluid enabling spermatogenesis
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7
Q

If the pituitary gland is removed, how is spermatogenesis stimulated?

A

-FSH and testosterone

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8
Q

What is the function of oestrogen in the testis?

A

-Increase sperm viability

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9
Q

What is nuclear condensation and when does it happen?

A

-Extrusion of the cytoplasm and condensation of the nucleus from spermatid to spermatozoon

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10
Q

What does the acrosome contain? Why?

A

-Golgi apparatus and hydrolytic enzymes to enable sperm to penetrate ovum

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11
Q

Identify the main feature of the midpiece of a spermatozoon

Why is this needed?

A
  • Mitochondria packed around either side

- Motility is a highly energy dependant process

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12
Q

What is the tail of a sperm made from?

A

-Flagellum produced by microtubules

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13
Q

What signals for the cytoplasm and organelles to be stripped from the permatid?

A

-Testosterone

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14
Q

What is different between the mature spermatozoa in the seminiferous tubules and the mature spermatozoa in the epididymis?

A

-Lack motility in the seminiferous tubules

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15
Q

What is spermiation?

A

-Release of spermatozoa from sertoli cells into seminiferous lumen

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16
Q

How are spermatozoa transported from seminiferous lumen to epididymis?

A

-Testicular fluid (produced by sertoli cells) and peristaltic contraction

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17
Q

How long can mature spermatozoa stay in the epididymis?

A

-Several months, eventually phagocytosed

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18
Q

How do the spermatozoa get into ductus deferens?

A

-Upon sexual arousal the epididymal wall contracts and expels the sperm into the ductus deferens

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19
Q

What are the phases of coitus?

A
  • Excitement phase
  • Plateau phase
  • Orgasmic phase
  • Resolution phase
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20
Q

What is the refractory period in males?

A

-After ejaculation it is not possible to ejaculate again upon further stimulation

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21
Q

Describe the excitement phase of the male sexual response

A
  • Sensory and psychological stimulation
  • Inhibition of sympathetic outflow (thoracolumbar)
  • Activation of parasympathetic outflow (sacral)
  • Ach-> M3 on endothelial cells of penile bvs -> increased Ca-> activation of eNOS -> NO production
  • Arterial vasodilation in corpora cavernosa
  • Increased penile blood flow
  • Penile filling (full of blood but not erect)
  • Penile tumescence (erection)
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22
Q

What happens to the testes and scrotum upon sexual arousal?

A

-Testes elevate and engorge and scrotal skin thickens and tenses

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23
Q

Describe the plateau phase of male sexual response

A
  • Activation of sacrospinous reflex
  • Contraction of ishiocavernosus -> compresses crus of penis and impedes venous return -> venous engorgement
  • Rise in intracavernosus pressure higher than systolic pressure -> decreased arterial inflow
  • Stimulation of secretion from accessory glands
  • Loss of erection unlikely
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24
Q

Which accessory glands are stimulated in the plateau phase of male sexual response?

A
  • Cowpers glands

- Littre’s glands

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25
Q

What are the two stages of orgasmic phase in male sexual arousal?

A
  • Emission

- Ejactulation

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26
Q

Describe the emission stage of orgasmic phase in male sexual response

A
  • Stimulation of sympathetic reflex
  • Contraction of smooth muscle in ductus deferens, seminal vesicle and prostate
  • Internal and external urethra contracts
  • Semen becomes pooled in urethral bulb
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27
Q

Describe the ejaculation stage of orgasmic phase of male sexual response

A
  • Sympathetic spinal reflex with cortical control
  • Further contraction of glands and ducts and sphincters
  • Filling of urethra stimulates pudendal nerve-> contractions of the genital organs, ischiocavernosus and bulbocavernosus -> expulsion of semen
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28
Q

Describe the resolution phase of the male sexual response

A
  • Activation of sympathetic outflow
  • Contraction of arteriolar smooth muscle in corpora cavernosa
  • Increased venous return
  • Detumescence and flaccidity
  • Testes descend and scrotum thins and relaxes
  • Refractory period entered
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29
Q

Describe the excitement phase of the female sexual response

A
  • Sensory and psychological stimulation
  • Activation of parasympathertic outflow; inhibition of sympathetic outflow
  • Vasocongestion causes vaginal lubrication to begin
  • Clitoris becomes engorged with blood
  • Uterus elevates, inner 2/3 of vagina lengthens and expands
  • Increased muscle tone, HR and BP
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30
Q

Describe the plateau phase of female sexual response

A
  • Further increase in muscle tone, HR and BP
  • Labia minora deepen in colour
  • Clitoris withdraws under its hood
  • Barthlin glands secretions lubticates vestibule for entry of penis
  • Orgasmic platform forms in lower 1/3 of vagina, upper 2/3 fully distended and uterus is fully elevated
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31
Q

Describe the orgasmic phase of the female sexual response

A
  • Orgasmic platform contracts rhythmically 3-15 times
  • Uterus contracts, anal sphincter contracts
  • Clitoris remains retracted under its hood
  • No refractory period - multiple orgasms possible
32
Q

In which direction does the uterus contract during a female orgasm?

A

-From fundus down to cervix

33
Q

Describe the resolution phase of the female sexual response

A
  • Clitoris descends and engorgement subsides
  • Labia returned to unaroused colour and size
  • Uterus descends
  • Vagina shortens and narrows back to unaroused state
34
Q

What happens to the breasts during female sexual response?

A
  • Breasts increase in size
  • Nipples become erect
  • Areola increases in size
  • Sex flush
35
Q

What is ‘the G spot’?

A
  • Area of erotic sensitivity located on the anterior wall of the vagina which can stimulate female ejaculation in some women
  • Tissue similar to prostate
36
Q

What happens to the female sexual response cycle with age?

A
  • Reduced desire
  • Reduced vasocongestion-> reduced vaginal lubrication
  • Vaginal and urethral tissue loose elasticity
  • Length and width of vagina decrease with reduced expansile capacity
  • Number of orgasmic contractions reduced
37
Q

What is the most common problem in sexual dysfunction? How can it manifest?

A
  • Desire

- Hypoactive, aversion, hyperactive nymphomania/satyriasis

38
Q

What is Kluver Bucci syndrome?

A

-Bilateral medial temporal lobe lesion causing hyperphagia, hypersexuality, hyperorality, visual agnosia and docility

39
Q

What is arousal sexual dysfunction in females?

A

-Persistent, recurrent inability to attain or maintain lubrication-swelling response

40
Q

What is arousal sexual dysfunction in males? Give some causes

A
  • Impotence

- Psychological, tissue damage, vascular damage, drugs (alcohol/anti-hypertensives)

41
Q

How does viagra work?

A

-Inhibits cGMP breakdown causing increased Ca and Increased NO production

42
Q

How much semen is produced in one ejaculation?

A

-2-4 ml

43
Q

How many sperm in one ejaculation?

A

-20-200x10^6/ml

44
Q

How many sperm are viable per ejaculation?

A

-60% (at least 30% abnormal)

45
Q

What is the definition of abnormal low sperm count?

A

-less than 20 million/ml

46
Q

Describe the glandular secretions from the seminal vesicles

A
  • Make up 60% of ejaculate

- Alkaline fluid to neutralise urethra, fructose for ATP production, prostaglandins and clotting factors (semenogelin)

47
Q

Why does semen contains prostaglandins?

A

-Increases sperm motility and female genital smooth muscle contraction

48
Q

Why does semen contain clotting factors?

A

-Liquefaction of semen in 1 hour

49
Q

Describe the glandular secretions from the prostate

A
  • 25% of ejaculate

- Milkym slightly acidic secretion containing proteolytic enzymes (PSA/pepsinogen) and citric acid

50
Q

Why do prostate secretions contain proteolytic enzymes?

A

-Activate clotting factors

51
Q

Describe the glandular secretions from the bulbourethral glands

A
  • 5% of ejaculate

- Alkaline fluid to neutralise distal urethra

52
Q

Where is semen depositied?

A

-High in the vagina near external os

53
Q

During the secretory phase of the uterine cycle, describe the mucus at the cervix
Why?

A

-Thick, sticky, acidic mucus plug to prevent bacterial inflow

54
Q

What is the function of oxytocin in sperm transport?

A

-Stimulates uterine contraction to propel sperm

55
Q

Describe cytoplasmic maturation in the oocyte

A

-Organelles become arranged around the periphery, lipid and protein synthesis occurs

56
Q

How many sperm does it take for fertilisation?

A
  • Out of 200-300 million sperm, ~300 reach the fertilisation site
  • 299+ sacrificed to disperse the zona pellucida -> 1 for fertilisation
57
Q

How long can sperm survive in the female genital tract?

A

-upto 5 days

58
Q

How long does the ovulated oocyte survive?

A

-6-24 hours before phagocytosis

59
Q

When is the fertile period when sperm needs to be depositied?

A

-Upto 3 days prior to ovulation and on day of ovulation

60
Q

How and how long does fertilised oocyte take to travel to uterus?

A

-3/4 days via peristalsis and cilia

61
Q

What does the sperm need to penetrate on the oocyte for fertilisation?

A
  • Corona radiata

- Zona pellucida

62
Q

What is capacitation?

A
  • The final stage of spermatozoa maturation which takes place in the female genital tract
  • Cell membrane changes to allow fusion with oocyte surface by removal of protein coat of sperm, exposing the acrosomal enzymes
  • Tail changes from beat to whip-like action
63
Q

What is the acrosome reaction?

A
  • When sperm pushes through granulosa cells of corona radiata it has intact acrosome
  • Protein coat then binds to ZP3 proteins of zona pellucida triggering acrosome reaction
  • Path digested through ZP and one sperm penetrates and fuses with oocyte forming zygote
64
Q

Where abouts in meiosis II of the oocyte is it halted?

A

-Metaphase

65
Q

Describe sperm-oolemma binding and fusion

A

The oocyte has two regions of its PM: that which directly overlies metaphase chromosomes and is devoid of microvilli and the rest is rich in microvilli protrusions. The sperm binds to the microvilli

66
Q

What is the fast block to polyspermy?

A

-As soon as a sperm penetrates the zona pellucida there is an electrical change in the oocyte membrane -> Na channels open increasing the membrane potential to +25 mv. This causes a wave of depolarisation which starts at the site of sperm entry and propagates across the cytoplasm -> this prevents sperm from fusing

67
Q

What is the slow block to polyspermy?

A
  • Ca released from ER induces local exocytosis of cortical granules-> granules release enzymes to stimulate adjacent granules to undergo exocytosis
  • Wave of exocytosis around the oocyte alters the zona pellucida in such a way that sperm can no longer penetrate
68
Q

What is syngamy?

A
  • Completion of meiosis II with extrusion of polar body

- Male and female pronuclei migrate towards each other and fuse to form diploid zygote

69
Q

What is polyploidy?

A

-Embryos containing 3 or more pronuclei (polyspermy of failure of polar body extrusion

70
Q

What is cleavage?

A

-A series of rapid mitotic divisions which increases zygote cell number but not size thus increasing the nucleus:cytoplasmic ratio

71
Q

How do monozygotic twins occur as a result of cleavage?

A

-Totipotent cells become divided into 2 separate individual cell masses

72
Q

How do you get non-identical twins?

A

-Two eggs ovulates, two eggs fertilised

73
Q

What is compaction?

A

-At the 8 cell stage, blastomeres undergo compaction where cells become polarised and communicate by tight junctions

74
Q

What is a morula?

A

-16 stage blastomere as embryo passes into uterus

75
Q

What is hatching?

A

-Local digestion of zona pellucida by enzymes produced by trophoblast so it can begin implantation

76
Q

Does the conceptus implant immediately after entered uterus?

A

-No, nourished in an intrauterine fluid for 2-3 days

77
Q

Where are spermatozoa produced?

A

-Seminiferous tubules

Repro (24 decks)

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