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ESA4 > 13 - Repro - Conception > Flashcards

13 - Repro - Conception Flashcards

1
Q

Name the 4 phases of coitus:

A

1) Excitement
2) Plateau
3) Orgasmic
4) Resolution

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2
Q

Define coitus:

A

Act of sexual intercourse resulting in the deposition of sperm into the cervix

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3
Q

Which types of neurons are activated/inhibited during the excitement phase of coitus?

A 
Activated = Sacral parasympathetic neurons
Inactivated = Thoracolumbar sympathetic neurons
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4
Q

How does the activation of parasympathetic neurons result in erection?

A
  • Ach acts on M3 receptors on endothelial
  • Gq receptors = ^Ca2+ = eNOS activation
  • ^NO production
  • vasodilation of corpora cavernosa
  • ^blood flow to penis
  • erection
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5
Q

What happens to the scrotal skin during the excitement phase of coitus?

A

Thickens + tenses

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6
Q

Which spinal reflex is activated during the plateau phase of coitus in males? What does this activate?

A

Sacrospinous reflex

  • Contraction of ischiocavernosus
  • Stimulation of bulbourethral glands
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7
Q

What happens to the testes during the plateau phase of coitus?

A

Become engorged + elevated

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8
Q

Which spinal reflex is activated during the orgasmic phase of coitus? What are the consequences of this in the male?

A

Thoracolumbar sympathetic reflex

  • Contraction of smooth muscle of vas deferens, prostate, seminal vesicles, internal and external urethral sphincters
  • Semen pools in urethral bulb (internal urethra)
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9
Q

What stimulates the pudendal nerve resulting in ejaculation?

A

Filling of the internal urethra (due to thoracolumbar sympathetic reflex)

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10
Q

What prevents a male from immediate repeated orgasms?

A

Refractory period due to penile flaccidity occuring in the resolution phase of coitus:
- vasoconstriction in corpora cavernosum allows restoration of venous flow

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11
Q

Describe the changes to the female genital tract during the excitement phase of coitus:

A
  • Clitoris engorges
  • Vaginal lubrication
  • Inner 2/3rds of vagina lengthens and expands
  • Uterus elevates
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12
Q

Describe the changes to the female genital tract during the plateau phase of coitus:

A
  • Labia minora deepen in colour
  • Clitoris withdraws under hood
  • Bartholin’s gland secretions lubricate vestibule
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13
Q

Where is the orgasmic platform of a female?

A

Outer 1/3rd of vagina

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14
Q

Why does ageing often reduce sexual desire?

A
  • Change in body shape = lower self-esteem
  • Decreased lubrication of female tract
  • Loss of elasticity of vaginal tissue
  • Decreased number of orgasmic contractions
  • More rapid resolution
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15
Q

Immediately post-ejaculation, what happens to prevent sperm being lost in the vagina?

A

Semen coagulates due to clotting factors (fibrinogen + semenogelin)

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16
Q

Which gland is responsible for the production of the clotting factors present in semen? Name the main 2 clotting factors:

A

Seminal vesicles:

  • Fibrinogen
  • Semenogelin
17
Q

What reactions occur during the passage of sperm from the cervix to the fallopian tube?

A
  • Capacitation

- Acrosome reaction

18
Q

What occurs during capacitation, and how long does it typically take?

A
  • Removal of glycoprotein coat - exposes acrosomal enzymes
  • Tail movements change from waves to whip-like motion

Several hours

19
Q

Which cells make up the corona radiata?

A

Follicular cells

20
Q

What triggers the acrosome reaction?

A

The passage of sperm through the corona radiata

21
Q

Describe the acrosome reaction:

A
  • Proteins on head of sperm bind to ZP3 proteins on zona pellucida
  • Signalling mechanism = ^Ca2+ and ^cAMP in sperm
  • Acrosomal enzymes digest through zona pellucida ~ 15 mins
22
Q

How long does it usually take for sperm to digest through the zona pellucida?

A

~ 15 minutes

23
Q

To which proteins on the zona pellucida do sperm bind to?

A

ZP3 proteins

24
Q

Name the reaction which prevents polyspermy:

A

Cortical reaction

25
Q

Describe the cortical reaction (to prevent polyspermy):

A

Fast block = Na+ channels open = depolarisation of oocyte membrane

Slow block = Ca2+ released from ER = exocytosis of cortical granules

26
Q

Approximately how many sperm per ejaculation reach the fertilisation site?

A

~ 300 sperm

27
Q

How many sperm are required to disperse the zona pellucida on average?

A

~ 299

28
Q

How long do sperm survive in the female genital tract?

A

~ 5 days

29
Q

When is the fertile period of the menstrual cycle?

A

Day 11-16 of menstrual cycle

30
Q

Define syngamy:

A

The union of male and female pronuclei to form a diploid zygote

31
Q

How can polyploidy occur?

A
  • Failure of cortical reaction

- Failure to extrude second polar body

ESA4 (36 decks)

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