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LCRS Endocrinology > Endocrinology of pregnancy > Flashcards

Endocrinology of pregnancy Flashcards

1
Q

In relation to the size of a sperm cell, how long is the journey of a sperm from testes to oviduct?

A

100,000 times the length of a sperm (<1/10^6 make it)

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2
Q

What happens to most of the tubular fluid in men?

A

It reabsorbed within the rate testis and early epididymis under the control of oestrogen

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3
Q

What produces tubular fluid?

A

Sertoli cells

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4
Q

What controls secretion of nutrients and other molecules into the epididymal fluid?

A

Androgens

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5
Q

What are the nutrients and other molecules for?

A

Provide journey for impending journey and coat the surface of the spermatozoon

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6
Q

Where does a vasectomy occur?

A

Vas deferens at the bottom end

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7
Q

How does concentration of spermatozoa compare in vas deferens compared to later on?

A

It is much higher at the vas deferens as lots of fluid is added along the way

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8
Q

What does semen consist of?

A

Spermatozoa
Seminal fluid
Leucocytes
Viruses (potentially)

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9
Q

What are some examples of components of seminal fluid that come from epidydimis/testis?

A

Inositol, carnitine, glycerylphosphorylcholine

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10
Q

What are some examples of components of seminal fluid that come from accessory sex glands (seminal vesicle and prostate)?

A

Fructose
Fibrinogen
Citric acid
Fibrinogenase and fibrinolytic enzymes

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11
Q

Why do you get fibrinogen and fibrinolytic enzymes in semen?

A

After ejaculation, the semen initially clots and then must be broken down

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12
Q

What are spermatozoa in the seminiferous tubule like?

A

Quiescent and incapable of fertilising an ovum

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13
Q

What are spermatozoa in the vas deferens like?

A

Capable of limited movement (whiplash)

Limited ability to fertilise

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14
Q

When is full activity and fertilising capability achieved?

A

When in the female reproductive tract

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15
Q

What is the process of reaching full activity and fertilising capability called?

A

Capacitation

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16
Q

What percentage of spermatozoa in ejaculate make it to the cervix?

A

1%

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17
Q

How do the spermatozoa achieve capacitation? (3 things)

A

Loss of glycoprotein coat
Change in surface membrane characteristics
Whiplash movements of the tail

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18
Q

Why can the spermatozoa lose the glycoprotein coat?

A

It has a protective function in the vagina but once in the uterus it isn’t necessary

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19
Q

What two things are all the components of capacitation reliable on?

A

Oestrogen and calcium

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20
Q

What happens to a sperm as it approaches an ovum?

A

There are changes in the membrane

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21
Q

What does a spermatozoon bind to?

A

ZP3 glycoprotein on zona pellucida

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22
Q

What happens after the spermatozoon binds to ZP3?

A

Progesterone stimulates the calcium influx into the spermatozoon

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23
Q

What does the calcium influx lead to in fertilisation?

A

Calcium dependent acrosome reaction

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24
Q

What does the calcium dependent acrosome reaction enable?

A

An exposed spermatozoon recognition site to bind to a second glycoprotein (ZP2)

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25
Q

What happens once ZP2 has bound?

A

The acrosome releases its enzymes allowing penetration of the zona pellucida so that the head of the spermatozoon can enter the ovum

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26
Q

Where does fertilisation normally occur?

A

Fallopian tubes

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27
Q

What does fertilisation lead to?

A

Expulsion of the second polar body and the zonal reaction

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28
Q

What is the zonal reaction?

A

Cortical granules release molecules which degrade the zona pellucida, this prevents further binding of other sperm. This is also calcium dependent

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29
Q

What is the conceptus?

A

The product of the zygote starting to divide (baby early days)

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30
Q

What happens to the conceptus as it moves from fallopian tubes to uterus?

A

It continues to divide

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31
Q

How long does it take for the conceptus to travel from fallopian tubes to the uterus?

A

3-4 days

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32
Q

How does the developing conceptus receive its nutrients until implantation?

A

Uterine secretions

33
Q

How long does the free living phase last (between formation and implantation)?

A

9-10 days

34
Q

While this occurs, the woman is in her luteal phase, what does this mean?

A

There will be high oestrogen and progesterone

35
Q

What does the conceptus first compact to form?

A

8-16 cell morula

36
Q

What does the 8-16 cell morula then become?

A

A blastocyst

37
Q

What are the two parts of the blastocyst and what do they become?

A

An inner cell mass- becomes the embryo

Trophectoderm- becomes the chorion which becomes the placenta

38
Q

What facilitates the transfer to the uterus?

A

Increasing progesterone:oestrogen ratio due to the luteal phase

39
Q

What is the reason for implantation?

A

Establishing a system for getting nutrients form the mother to all cells in the embryo

40
Q

What does the initial attachment phase consist of?

A

Outer trophoblast cells making contact with the uterine surface epithelium

41
Q

What is the decidua?

A

Thick layer of modified mucous membrane which lines the uterus during pregnancy and is shed with afterbirth

42
Q

When does decidualisation of the underlying stromal tissue occur?

A

Within a few hours of implantation

43
Q

Which two molecules are of particular importance in attachment?

A 
Leukaemia inhibitory factor (LIF)
Interleukin 11 (IL-11)
44
Q

Where does leukaemia inhibitory factor come from?

A

Endometrial secretory glands

45
Q

What does leukaemia inhibitory factor do?

A

Stimulation adhesion of the blastocyst to the endometrial cells

46
Q

Where does interleukin-11 come from?

A

Endometrial cells

47
Q

What is interleukin-11 released into?

A

Uterine fluid

48
Q

What is the decidualisation reaction?

A

Invasion of the underlying uterine stromal tissue by the trophoblast cells of the blastocyst

49
Q

What happens within hours due to the decidualisation reaction?

A

Increased vascular permeability in the invasion region

Localised changes in intracellular composition and progressive sprouting and growth of capillaries

50
Q

What factors are involved in the decidualisation reaction?

A

Mainly IL-11
Histamine
Certain prostaglandins
TGFbeta- promotes angiogenesis

51
Q

When does hCG reach a peak?

A

8 weeks

52
Q

When is hCG vital and why?

A

First 6 weeks as its job is to replace LH

53
Q

What happens in terms of hormones that leads to menstruation?

A

Levels of oestrogen and progesterone fall

54
Q

Why is hCG released during pregnancy?

A

It is needed to maintain the stimulation of oestrogen and progesterone

55
Q

What produces hCG?

A

Trophoblast cells

56
Q

How does hCG work?

A

It can bind to LH receptors on corpus luteum hence replacing the effects of LH

57
Q

Why are the ovaries no longer necessary in a pregnancy after 5 weeks?

A

The placenta will have taken over production of the hormones

58
Q

What happens to oestrogen and progesterone levels throughout pregnancy?

A

They increase and until the end, progesterone remains the dominant influence

59
Q

What is human placental lactogen?

A

It is produced by the placenta
Growth hormone
Prolactin like effects

60
Q

What are the three components important in providing steroids?

A

Mother
Foetus
Placenta

61
Q

What does the mother provide in terms of steroids?

A

The precursors

62
Q

What is the most common precursor?

A

Pregnenolone which leads to progesterone

63
Q

What causes steroid production in the foetus?

A

Progesterone

64
Q

What precursor does the foetal and maternal adrenals produce?

A

Dehydroepiandrosterone sulfate (DHEAS)

65
Q

What is DHEAS taken up by the placenta to produce?

A

Oestradiol and small amounts of oestrone

66
Q

What is the main oestrogen of pregnancy?

A

Oestriol

67
Q

If you wanted to look at the health of the baby, which oestrogen would you look at?

A

Oestriol because its source is completely foetal

68
Q

How is oestriol formed?

A

It comes from the conjugation of DHEAS in the foetal liver to form 16alpha-hydroxy DHEAS which then goes to the placenta which deconjugates it and uses it to form estriol

69
Q

What happens to most maternal hormones during pregnancy?

A

They increase

70
Q

What happens to the pituitary during pregnancy?

A

It enlarges

71
Q

What is responsible for the action of parturition?

A

Contraction of actin and myosin filaments

72
Q

What does the contraction of the filaments (parturition) require?

A

Calcium

73
Q

Why is oestrogen stimulating the production of prostaglandins important for parturition?

A

The prostaglandins stimulate the production and release of calcium into the cytoplasm from intracellular stores

74
Q

What effect does progesterone have in relation to parturition?

A

Opposite effect to oestrogen
Inhibits prostaglandin synthesis
Inhibits oestrogen receptors

75
Q

At parturition, oxytocin will be released, what effect will this have?

A

It will bind to its receptor and open calcium channels allowing calcium ions to move in from outside

76
Q

What does prolactin do?

A

Promotes milk synthesis

77
Q

What does oxytocin do?

A

Promotes milk ejection

78
Q

How are prolactin and oxytocin linked neurologically?

A

They have the same neuroendocrine reflex

LCRS Endocrinology (18 decks)

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