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MEDI 202 - Genes To Community > Hormonal Changes Before & During Pregnancy > Flashcards

Hormonal Changes Before & During Pregnancy Flashcards

1
Q

What is folliculogenesis?

A

The process where a recruited primordial follicle grows into a Graafian one.

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2
Q

What is oogenesis?

A

The formation of egg cells, which are part if the follicle so technically, oogenesis is part of folliculogenesis.

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3
Q

When do hormonal changes occur?

A

During menstrual cycle, during fertilisation, during pregnancy all the way until labour.

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4
Q

What is the main function of the placenta that take place?

A

To provide efficient nutrient and oxygen supply for fetal growth.

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5
Q

What is a primordial follicle?

A

A primary oocyte arrested in meiotic prophase I. Surrounded by a single layer of follicular cells without zone pellucida.

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6
Q

How many primordial follicles are there during different phases of life?

A

Mid-pregnancy: 7 million
At birth: 1 to 2 million
Menstrual Cycle: 12 to 20 follicles will be stimulated to grow each cycle
At menopause: less than 1000

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7
Q

How many primordial cells actually become a Graafian follicle?

A

Out of the 12 to 20, only one matures to become a Graafian follicle, and be released.

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8
Q

Why is there a decrease from 7 million to 1 to 2 million primordial follicles?

A

Most of them undergo atresia and die.

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9
Q

What kind of receptors do granuloma cells have?

A

They initially express FSH receptors and later on they express LH ones.

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10
Q

What kind of receptors do theca cells have?

A

They express LH receptors.

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11
Q

What is the process of oogenesis during the fetal period?

A

Fetal Period: Oogonium undergoes mitosis and turns into a primary follicle, meiosis is in progress and the primary oocyte is stuck at prophase I until puberty.

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12
Q

What is the process of oogenesis during puberty?

A

Every month one primary oocyte completes meiosis I and it develops into one polar body a secondary oocyte. From there on meiosis II may occur to form two polar bodies.

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13
Q

What is the process of oogenesis after fertilisation?

A

In the case of fertilization, the secondary oocyte completes meiosis II to produce an ovum and a second polar body.

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14
Q

How is a primary oocyte arrested in meiosis I?

A

Granulosa cells release cGMP which inhibits the PDE3A enzyme in the oocyte and blocks cAMP degradation. cAMP increases and thus meiosis is arrested.

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15
Q

How does meiosis I resume?

A

Pre-ovulatory LH surge inhibits cGMP production by granuloma cells which decreases cAMP production and thus resumes meiosis.

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16
Q

How is GnRH released?

A

In pulses

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17
Q

Menstrual Cycle Hormones Regulated

A

The patterns of pulsation of GnRH secrete specific hormones. Low-frequency pulsations favours FSH release while high-frequency favours LH release.

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18
Q

Where is LH released from?

A

Corpus luteum

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19
Q

Why can’t granuloma cells produce oestrogen on their own?

A

They require androgens which are produced by the theca cells.

20
Q

What changes to the receptors of the granuloma cells during the follicular phase?

A

They have FSH receptors

21
Q

What do theca cells produce?

A

Androgens

22
Q

What do granuloma cells produce?

A

Progesterones

23
Q

What is the hypothalamic-pituitary-ovarian axis?

A

A tightly regulated system controlling female reproduction

24
Q

Does oestrogen usually have positive or negative feedback?

A

Oestrogen can have both, but usually it is negative except of when it is required for ovulation, as it secretes LH.

25
Q

Explain HPO axis

A

GnRH from the hypothalamus causes release of FSH and LH from the anterior pituitary which stimulate ovarian hormones.

26
Q

What is the function of inhibin?

A

Negative feedback and it inhibits FSH secretion by the anterior pituitary.

27
Q

Which primary follicle survives?

A

The largest one, with the most FSH support.

28
Q

What causes atresia?

A

The lack of support of FSH, as large volumes of androgens are released from the dominant follicle.

29
Q

What are the functions of the placenta?

A

Support: provide nutrients and oxygen
Immunity: suppress the maternal immune system to prevent immunologic rejection
Endocrine: hormone synthesis, transport and metabolism

30
Q

Where does the embryo get its nutrients from prior to the formation of the placenta?

A

Trophoblastic digestion and absorption of nutrients from endometrial decidua.

31
Q

Which hormone is similar to LH during pregnancy?

A

hCG, human chorionic gonadotropin, maintains corpus luteum and secretes progesterone and oestrogen.

32
Q

Why is oestrogen higher towards the end of the pregnancy?

A

It helps with the relaxation of smooth muscle so makes labor and delivery easier.

33
Q

Which hormone is detected to present a positive pregnancy result?

A

hCG

34
Q

What effect does oestrogen have during pregnancy?

A

Enlargement of ovaries, uterine tubes, uterus, vagina, breasts and female external genitalia.

It also causes renal sodium and water retention which leads to oedema and swelling.

35
Q

What is the function of progesterone during pregnancy?

A

Development of decidua, essential for nutrition,
Decreases frequency of uterine contractions, less of a chance for miscarriage.
Promotes development of lobules and alveoli in breasts
Inhibits T lymphocyte-mediated rejection of placenta

36
Q

What is the effect of human chorionic somatomammotropin?

A

Stimulates breast development and lactation
Decreases insulin sensitivity, and decreases utilisation of glucose from the mother
Promotes release of free fatty acids

Similar effects as prolactin and growth hormone

37
Q

Where is human chorionic somatomammotropin produced?

A

Syncytiotrophoblasts

38
Q

What is the effects of relaxin during pregnancy?

A

Inhibits uterine contraction
Relaxes pubic symphysis
Development of mammary glands
Vasodilator, increased renal blood flow, venous return and cardiac output

39
Q

What is the effect of relaxin at the time of delivery?

A

Softens and dilates uterine cervix

40
Q

What happens to the anterior pituitary gland during pregnancy?

A

Increases 50% in size

41
Q

Which anterior pituitary hormones increase during pregnancy?

A

Corticotropin
Thyrotropin
Prolactin

42
Q

Which anterior pituitary hormones decrease during pregnancy?

A

FSH and LH due to high levels of oestrogen

43
Q

What happens to the adrenal cortex during pregnancy?

A

Glucocorticoids increase so synthesise tissues in the fetus.
Aldosterone secretion increases so increase in renal retention so pregnancy induced hypertension

44
Q

What happens to the thyroid gland during pregnancy?

A

50% increase in size

45
Q

What happens to the parathyroid glands?

A

increase in size and produce for PTH

46
Q

Why does PTH production increase?

A

Calcium released from mother’s bones moves to the fetus in order to ossify its own bones, so PTH increases to provide calcium for both

47
Q
A

MEDI 202 - Genes To Community (23 decks)

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