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Reproduction > 6.1 Sexual Function And Fertilisation > Flashcards

6.1 Sexual Function And Fertilisation Flashcards

1
Q

Where is the majority of semen produced?

A

The accessory glands

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2
Q

What is the function of accessory glands secretion?

A
  • transport medium for sperm
  • neutralises acidic environment of vagina ( buffering capability )
  • nutrition source for spermatozoa
  • Prostaglandins in the secretion stimulate muscular activity in the female tract
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3
Q

Why does semen initially clot?

A

Due to clotting factors provided by the seminal vesicles.

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4
Q

How is semen unclotted?

A

By the substance from the prostate that contains specific enzymes to break down the coagulation

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5
Q

What factors of sperm are considered when looking at issues with infertility?

A

Time taken to breakdown coagulation of semen

Amount, morphology and motility of sperm

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6
Q

What are the 4 phases in the human sexual response?

A

Excitement phase
Plateau phase
Orgasm phase
Resolution phase

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7
Q

What are the 2 main stimuli for the excitement phase?

A

Psychogenic

Somatic

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8
Q

What is the refractory phase?

A

A phase after the orgasm phase where the individual returns to haemodynamic norm

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9
Q

How does the resolution phase vary between males and females?

A

Men have a refractory period whilst women do not.

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10
Q

In the excitement phase in men, what neurones result in an erection?

A

Parasympathetic efferent from the pelvic nerve

Somatic efferents from the pudendal nerve

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11
Q

Describe the physiology of an erection

A
  1. Parasympathetic in the pelvic nerve stimulate smooth muscle relaxation
  2. Sinusoids in the corpus cavernous relax
  3. Arterial dilation
  4. Increased blood flow against the though tunica albuginea surrounding the corpus cavernosa
  5. Compression of venous drainage
  6. Blood is prevented from leaving the penis, engorgement of the arteries causes erection.
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12
Q

Why is it important the the corpus spongiosum does not become completely compressed by the erection?

A

As the urethra runs in the corpus spongiosum. Urethra needs to remain open to allow the semen to leave

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13
Q

Describe the neurotransmitters involved in maintaining an erection

A

Parasympathetic neurones from the pelvic and cavernous nerve secrete ACh.
ACh acts on M3 receptor to increase calcium intracellular levels.
Calcium activates NO synthase, producing citrulline and NO in the breakdown of arginine.
No is the key intracellular transmitter stimulation vasodilation via guanylyl cyclase using GTP to form Cyclic GMP. This pathway continues and results in smooth muscle relaxation.

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14
Q

Disruption to which factors can call erectile dysfunction?

A 
Psychological input
Vascular disorder
Anti-hypertensives
Neurological disorders 
Trauma of the fibrous tissue of the corpus cavernosa
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15
Q

How does viagra work to help patients with erectile dysfunction?

A

Increases the amount of cGMP in the cells by stopping the breakdown of cGMP by phosphodiesterase

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16
Q

What occurs in the emission stage in men?

A

Semen moves into the prostate urethra. This occurs due to smooth muscle contraction from the prostate, vas deferents and seminal vesicles.

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17
Q

What is ejaculation?

A

The expulsion of semen

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18
Q

What structures contract during ejaculation?

A

The glands
Ducts
Bladder Internal sphincter
Rhythmic striatal contractions

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19
Q

Why does the internal sphincter contract during ejaculation?

A

To avoid retrograde ejaculation and sperm entering the bladder

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20
Q

What’s the nervous supply that controls emission and ejaculation of semen?

A

Sympathetic control

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21
Q

What is capacitation?

A

The final step of sperm to become fully mature.Occurs in the female reproductive tract at the cervix.
Sperm cell membrane changes to allow fertilisation, tail movement changes.

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22
Q

Describe how a sermon fertilises an oocyte

A

Enzymes in the across membrane released to remove outer granuloma cells that are still surrounding the ovum as the corona radiata.
Sperm interacts with zona pellucida causing acrosome reaction.
Single head of sperm will penetrate ovum and fuse with the membrane

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23
Q

What does the cortical reaction do?

A

Prevents further sperm from entering

Trigger meiosis II of the ovum to complete.

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24
Q

What’s special about the cells of the morula?

A

Totipotent

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25
Q

What is hatching?

A

When the zona pellucida degenerates, allowing the morula to continue dividing. The blastocyst can then implant into the endometrial lining.

26
Q

Where does the embryo implant?

A

In the postero-superior surface of the uterine cavity. In the stroma of the endometrium

27
Q

What structural adaptations does the stroma undergo in preparation for implantation ?

A

Increased secretory glands

Increased vasculature

28
Q

What is the window of fertility?

A

3 days before ovulation

Ovum has a maximum life span of 24 hours, Sperm can survive 72 hours in the female reproductive tract

29
Q

What maintains the endometrium in the waiting phase after ovulation?

A

The corpus luteum

30
Q

What is the lifespan of the corpus luteum?

A

14 days

31
Q

How many sperm are produced a day?

A

100 million

32
Q

What are the 2 specialised cells in the testis?

A

Leydig cells

Sertoli cells

33
Q

What are the 3 components of the accessory glands?

A

Seminal Vesicles
Prostate gland
Bulbourethral glands

34
Q

Describe the fraction of the seminal plasma produced at the accessory glands?

A

Seminal vesicle - 60%
Prostate gland - 25%
Bulbourethral glands - V. Small volume

35
Q

What is the function of secretions of the seminal vesicles?

A
  • alkaline , neutralises acid in the male urethra and female reproductive tract.
  • fructose, prostaglandins and clotting factors
36
Q

What is the function of the secretions of the prostate gland?

A
  • acidic, buffering
  • proteolytic enzymes (breakdown clotting proteins)
  • citric acid, acid phosphatase
37
Q

Describe the secretions of the bulbourethral glands?

A
  • alkaline fluid

- a mucous that lubricates the end of the penis and urethral lining

38
Q

What’s the normal volume of ejaculation?

A

2 - 6ml

39
Q

What’s the usual pH of semen?

A

7 - 8

40
Q

Where is the normal fertilisation site of the ovum?

A

Ampulla

41
Q

Which nerves release Ach in the stimulation of an erection?

A

Parasympathetic post ganglionic neurones

42
Q

What GPCR is responsible for the initiation of an erection?

A

M3 receptor on endothelial cells.

43
Q

How does NO enter vascular smooth muscle?

A

2 ways

  • released directly from nerves (cavernous nerve )
  • rise in intracellular calcium vie activation of M3 receptor triggers formation of intracellular NO
44
Q

What is sildenafil?

A

A.k.a viagra. It is a PDE V inhibitor. Frequently used to treat erectile dysfunction

45
Q

What spinal level does the stimulation of an erection stem from?

A

Point = parasympathetic

Reflexogenic pathway = S2 - S4

46
Q

At what spinal level does the innervation for ejaculation stem from?

A

Shoot = Sympathetic

Psychogenic pathway T10 to L2

47
Q

What action does oestrogen have on the mucus of the cervix?

A

Just oestrogen = thin stretchy mucus

48
Q

During the lateral phase, when oestrogen and progesterone are being released, how does the composition of the cervical fluid vary?

A

Previously thin and stretchy -> now thick and sticky to prevent further sperm entering.

49
Q

What is a fern test?

A

Detection of a fern like pattern of vaginal secretions when a specimen is allowed to dry on a glass slide and viewed under a microscope. Used to provide evidence for the presence of amniotic fluid

50
Q

What is Spinnbarkeit mucus?

A

Cervical mucus at the time of ovulation. Cervical fluid is abundant clear and strechable

51
Q

Describe the change in female physiology during sex

A
  1. Excitement = labia swell, clitoris enlarges, vaginal lubrication, flexes posteriorly
  2. Plateau = Vagina expands, uterus elevates, orgasmic platform
  3. Orgasm = Contractions in uterus, rhythmic contractions in orgasmic platform
  4. Resolution = uterus lowers, orgasmic platform disappears.
52
Q

Where is the semen deposited after sex?

A

At the entry of the cervix

53
Q

What is the fertile period?

A

Sperm deposition up to 3 days prior to ovulation or day of ovulation

54
Q

How are gametes transported?

A

Oocyte : cilia beating and peristalsis of uterine tube

Sperm : own propulsion

55
Q

How is the acrosome reaction triggered?

A

Sperm pushes through the corona radiata
Binds to the sperm surface receptor on the zona pellucida (ZP3 glycoprotein)
Triggers autosome reaction

56
Q

What reaction takes place to block polyspermy?

A

Cortical reaction.

57
Q

What occurs on fertilisation?

A

Series of calcium waves are activated following fusion of the oocyte and sperm membranes. Completion of meiosis II of the female gamete.

58
Q

What happens in assisted reproductive technology?

A

Oocytes fertilised in vitro, allowed to divide to the 4-8 cell stage. Morula transferred into the uterus.

59
Q

What happens in pre-implantation genetic diagnosis?

A

A single cell is removed from the morula and tested for serious heritable conditions before transferring the embryo into the mother

60
Q

After hatching, what occurs next?

A

Implantation

61
Q

Where does the uterus implant in placenta praevia?

A

Into the lower uterine segment

62
Q

What part of the embryo interacts with the endometrium?

A

The synctiotrophoblast

Reproduction (11 decks)

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