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YR2: Endocrinology > Endocrinology of Pregnancy > Flashcards

Endocrinology of Pregnancy Flashcards

1
Q

Where is tubular fluid reabsorbed and what controls this process?

A

Rete testis
Early epididymis
Induced by oestrogen

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2
Q

Where do you find oestrogen within the male reproductive tract?

A

Tubular fluid produced by sertoli cells

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3
Q

What stimulates the release of nutrients and other molecules (e.g. glycoproteins) into the epididymal fluid?

A

Androgens

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4
Q

What are the roles of androgen induced secreted nutrients and molecules?

A

Nutrients provide energy for impending journey

Glycoproteins coat surface of the spermatozoon (to protect from hostile environment)

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5
Q

Within which part of the male reproductive tract is fluid reabsorbed and secretory products put in?

A

Epididymis

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6
Q

Why is the concentration of sperm in the vas deferens higher than further down the reproductive tract?

A

Further down the reproductive tract, other fluids + secretory products are added thus diluting the sperm.

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7
Q

Which structures contribute to the seminal fluid?

A

Epididymis/testes (small contribution)
Seminal vesicle (2/3)
Prostate (1/3)
Bulbourethral glands

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8
Q

What is semen comprised of?

A

Spermatazoa
Seminal fluid
Leucocytes
Potential viruses

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9
Q

When do sperm achieve full activity and what is the name given to this process?

A

Capacitation

Occurs within ionic + proteolytic environment of Fallopian tube

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10
Q

What 3 changes take place in capacitation?

A

Loss of glycoprotein coat
Change in surface membrane characteristics (leading to acrosome reaction when in close proximity to the ovum)
Whiplash movements of the tail

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11
Q

What are capacitation changes dependent on?

A

Oestrogen

Calcium

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12
Q

Describe the acrosome reaction.

A

Sperm binds to ZP3 glycoprotein on zona pellucida
Once bound, progesterone stimulates Ca2+ influx into the sperm
Causes release of hyaluronidase + proteolytic enzymes from acrosome
Results in penetration of the zona pellucida

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13
Q

Where does fertilisation normally occur? What does fertilisation result in the expulsion of?

A

Fallopian tube

Expulsion of Second polar body

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14
Q

The zonal reaction immediately follows fertilisation. Describe the zonal reaction.

A

Cortical granules release molecules that degrade the zona pellucida (including ZP3 + ZP2)
Prevents further binding of other sperm
Ca2+ dependent
The cell is now diploid

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15
Q

How does the conceptus receives nutrients before implantation? Describe the conceptus at this point

A

Uterine secretions provide nutrients

Continues to divide as it moves down Fallopian tube

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16
Q

How long is this free-living phase of the conceptus?

A

9-10 days

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17
Q

In what stage of the menstrual cycle does the development of the conceptus occur?

A

Luteal phase– oestrogen + progesterone are high

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18
Q

What does the conceptus compact to form?

A

8-16 cells morula

19
Q

What are the two parts of the blastocyst?

A

Inner cell mass: becomes the embryo

Trophectoderm: becomes the chorion (which becomes the placenta)

20
Q

What hormonal change facilitates the transfer of the conceptus to the uterus?

A

Increasing progesterone: oestrogen ratio

21
Q

What is a decidua?

A

Thick layer of modified mucous membrane, which lines the uterus during pregnancy + is shed after birth

22
Q

What hormone environment is required for decidualisation phase of implantation?

A

Progesterone dominance in the presence of oestrogen

23
Q

State 2 molecules that are of particular importance in implantation. Mention which cells produce these molecules.

A

Leukaemia inhibitory factor (LIF)
Produced by endometrial secretory glands
Stimulates adhesion of blastocyst to endometrial cells
IL-11
Also released from endometrial cells + into uterine fluid
Also may be involved

24
Q

In decidualisation, what endometrial changes due to progesterone occur?

A

Glandular epithelial secretion
Glycogen accumulation in stromal cell cytoplasm
Increased vascular permeability in the invasion region, associated with oedema of tissues
Growth of capillaries

25
Q

Which chemical factors are involved in decidualisation?

A

Mainly IL-11
Histamine
Certain prostaglandins
TGF-beta (promotes angiogenesis)

26
Q

What is the role of hCG and when does it peak?

A

Peaks at 8 weeks + is particularly important in 1st 6 weeks
Mimics LH by binding to LH receptors on the corpus luteum + stimulating the production of oestrogen + progesterone
Produced by trophoblast cells

27
Q

What change takes place after about 6 weeks?

A

Role of hormone production is transferred from the corpus luteum (stimulated by hCG) to the placenta

28
Q

Describe how oestrogen and progesterone levels change throughout pregnancy.

A

Oestrogen + progesterone levels continue to rise through pregnancy with progesterone always being the dominant influence

29
Q

What is the role of human placental lactogen?

A

Involved in changes in metabolism
Causes insulin resistance so mother has higher glucose levels
Promotes nutrients going to baby

30
Q

Which steroid precursor tends to be provided by the mother for the foetus?

A

Pregnenolone

31
Q

Which androgen is formed by the maternal and foetal adrenals? This is used as a precursor for oestrogen production.

A

Dehydroepiandrosterone Sulphate (DHEAS)

32
Q

Which oestrogens are produced by the placenta using DHEAS from the mother and foetus?

A

Oestradiol

Oestrone

33
Q

Oestradiol + Oestrone aren’t a good measure of foetal health. Explain why.

A

These oestrogens are dependent on precursor production from the both the foetal + maternal adrenals.
Therefore, it is not a good measure of foetal health.

34
Q

What is the main oestrogen of pregnancy? Describe how it is produced.

A

OESTRIOL
DHEAS from the foetal adrenals is conjugated in the foetal liver to form 16-alpha-hydroxy DHEAS
16-alpha-hydroxy DHEAS is then de-conjugated in the placenta + used to produce oestriol

35
Q

Describe how maternal hormones change in pregnancy.

A 
Most increase (pituitary becomes enlarged):
ACTH
Corticotrophin
Prolactin
IGF1 
Iodothyronines
Adrenal steroids 
PTH related peptides
Hormones that decrease: 
Gonadotrophins
Pituitary GH (because placental GH variant increases towards term)
TSH
36
Q

What biochemical change is required for contraction of the uterus during parturition?

A

Increase in intracellular Ca2+ concentration

37
Q

Describe how oestrogen increases the chance of contraction.

A

Oestrogen binds to oestrogen receptors + triggers synthesis of prostaglandins within the endometrial cells.
Prostaglandins stimulate the release of Ca2+ from intracellular stores.

38
Q

Describe how oxytocin increases the chance of contraction.

A

Oxytocin binds to its receptor on the endometrial cell + opens Ca2+ channels, allowing Ca2+ ions to move in from outside

39
Q

Describe the effect of progesterone on the contraction process.

A

Progesterone keeps the effects of oestrogen under control

by inhibiting oestrogen receptors + the production of prostaglandins

40
Q

What change occurs when the foetus reaches a particular size, which is crucial for contraction to take place?

A

A switch in steroid synthesis from progesterone synthesis to oestrogen synthesis
Leads to oestrogen dominance –> prostaglandin production –> Ca2+ release from intracellular stores –> promotion of muscle contraction

41
Q

What 2 hormones are involved in milk production and milk ejection?

A

Prolactin: milk production
Oxytocin: milk ejection
Both have a similar neuroendocrine reflex arc stimulated by suckling

42
Q

What are the 2 phases of implantation? Describe them

A

Attachment phase: Outer trophoblast cells contact uterine surface epithelium
Decidualisation phase: changes in underlying uterine stromal tissue

43
Q

List 3 key roles of Oxytocin

A

Uterine contraction
Cervical dilation
Milk ejection

44
Q

Which hormone is produced by the foetus around the time of partruition?

A

Cortisol

YR2: Endocrinology (19 decks)

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