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Yr 2 LCRS - Endo > 11 - Endocrinology of Pregnancy > Flashcards

11 - Endocrinology of Pregnancy Flashcards

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1
Q

How many spermatozoa are present in the semen from ejaculation?

A

15-120 million/ml

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2
Q

How much seminal fluid is present in the semen from ejaculation?

A

2-5ml

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3
Q

What does semen consist of?

A

Spermatozoa

Seminal fluid

Leukocytes

Potentially viruses (e.g. Hepatitis B, HIV)

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4
Q

How many spermatozoa from the ejaculate enter the cervix?

A

1 in 100

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5
Q

How many spermatozoa from the ejaculate start to travel from the cervix to ovum?

A

1 in 10,000

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6
Q

How many spermatozoa from the ejaculate start to travel from the cervix to ovum?

A

1 in 1 million

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7
Q

Where does seminal fluid come from?

A

Mainly from accessory sex glands:

  • seminal vesicles
  • prostate
  • bulbourethral glands

Small contribution from:

  • epididymis
  • testis
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8
Q

What is capacitation of sperm?

A

A functional maturation of the spermatozoon.

Only occurs in female reproductive system, can’t happen in the male

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9
Q

What is the purpose of capacitation of sperm?

A

To allow them fertilising capability in the female reproductive tract

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10
Q

Outline what occurs in capacitation of sperm

A

1) Loss of glycoprotein ‘coat’
2) Change in surface membrane characteristics
3) Develop whiplash movements in tail

Steps 2 and 3 are capacitation

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11
Q

Where does capacitation of sperm occur?

A

Takes place in ionic and proteolytic environment of the Fallopian tube

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12
Q

What does the process of capacitation depend on?

A

Oestrogen dependent

Ca2+ dependent

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13
Q

What does the spermatozoon bind to on the ovum?

A

ZP3 glycoprotein

- sperm receptor

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14
Q

What does the spermatozoon penetrate before ovum membrane?

A

Zona Pellucida

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15
Q

What occurs after the spermatozoon binds to ZP3?

A

Ca2+ influx into sperm

- stimulated by progesterone

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16
Q

Where does fertilisation occur?

A

Within the Fallopian tube

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17
Q

What does fertilisation trigger?

A

Cortical reaction

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18
Q

What occurs in the cortical reaction?

A

Cortical granules in the ovum release molecules which degrade the Zona Pellucida (e.g. ZP2 and 3)

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19
Q

How does the cortical reaction stop other sperm binding to the ovum?

A

The Zona Pellucida is degraded, so sperm can’t bind as there are no receptors

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20
Q

What occurs to the chromosome number of the ovum during fertilisation?

A

Goes from haploid to diploid

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21
Q

After fertilisation, how long can the free-living phase last before it attaches to the uterus?

A

Up to 9-10 days

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22
Q

What is the conceptus?

A

The whole product of conception at any stage of development, from fertilization of the ovum to birth.

It denotes the embryo and its adnexa (appendages or adjunct parts) or associated membranes (i.e. the products of conception).

The conceptus includes all structures that develop from the zygote, both embryonic and extraembryonic.

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23
Q

What does the conceptus receive nutrients from whilst free-living?

A

Uterine secretions

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24
Q

What occurs to the conceptus in the first 3-4 days after fertilisation?

A

Continues to divide as it moves down Fallopian tube to uterus

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25
Outline the development conceptus from fertilised egg to blastocyst
Fertilised egg 2-cell conceptus 4-cell conceptus 8-cell conceptus COMPACTION Morula Blastocyst
26
What is compaction?
Change in the shape of the conceptus
27
Describe the structure of blastocyst
Blastocoelic Cavity - in the middle ``` Trophoblast Cells (Chorion) - round the edge ``` Inner Cell Mass (Embryo)
28
What are the phases of implantation of the conceptus?
Attachment Phase Decidualisation Phase
29
What is the Attachment Phase of implantation of the conceptus?
Outer trophoblast cells contact uterine surface epithelium
30
What is the Decidualisation Phase of implantation of the conceptus?
Changes in underlying uterine stromal tissue Occurs within a few hours after fertilisation Begins to implant
31
What hormones are essential for implantation?
Progesterone domination in the presence of oestrogen
32
What percentage of the testes are dedicated to producing sperm?
90%
33
What cells do the testes consist of and what does each cell make?
Sertoli Cells in centre - make sperm Leidig Cells around edge - make testosterone
34
What hormone induces tubular fluid reabsorption in the male reproductive tract?
Oestrogen induces tubular fluid reabsorption This concentrates the sperm
35
Where is male oestrogen made?
Mainly from the conversion of testosterone (from Leidig Cells) to oestrogen by the enzyme aromatase
36
What occurs in a man with aromatase deficiency?
AROMATASE NEEDED TO CONVERT TESTOSTERONE TO OESTROGEN May be infertile May be very tall because long bones continue to grow as oestrogen is needed to close epiphyses May get osteoporosis as oestrogen protects bone May not present for a while because they have normal testosterone levels
37
What occurs in a woman with aromatase deficiency?
She will be virilised as aromatase is needed to convert testosterone to oestrogen Therefore, she will have high levels of testosterone
38
How do sperm get nutrients and their protective coating initially when being made in the testes?
Androgens induce nutrient and glycoprotein secretion into the epididymal fluid
39
How far does a spermatozoa travel from the testis to the fallopian tube?
100,000x its length
40
What are the reasons for having a high number of sperm in semen?
Only 1 in 1 million reach the ovum Also, some sperm do not have good motility
41
What is the acrosome reaction?
Sperm binds to ZP3 Ca2+ influx into sperm (stimulated by progesterone) Release of hyaluronidase and proteolytic enzymes from acrosome --> The sperm can then penetrates the Zona Pellucida
42
What is the acrosome in a sperm?
An organelle that develops over the anterior half of the head in the spermatozoa It binds to the Zona Pellucida around the ovum via ZP3 on the ovum
43
What is the Zona Pellucida made up of?
Glycoprotein
44
If fertilisation does not occur in the fallopian tube, what is the pregnancy called?
An ectopic pregnancy
45
What is the polar body?
When the egg forms through meiosis, half the chromosomes go to one and half to the other but one takes all the cytoplasm A polar body is a small haploid cell that is formed concomitantly as an egg cell during oogenesis, but which generally does not have the ability to be fertilized. When certain diploid cells in animals undergo cytokinesis after meiosis to produce egg cells, they sometimes divide unevenly. The polar body eventually degrades
46
What the trophoblast cells (chorion) surrounding the blastocyst go on to form once the egg has implanted?
The placenta
47
Explain what the uterine lining consists of
Endometrial lining with secretory glands
48
What does the uterine lining secrete to help with blastocyst attachment?
LIF (Leukaemia Inhibitory Factor) IL11 (Interleukin 11) Many other molecules e.g. HB-EGF
49
What is the role of LIF (Leukaemia Inhibitory Factor)?
Stimulates adhesion of blastocyst to endometrial cells From endometrial secretory glands (and blastocyst?)
50
What is the role of IL11 (Interleukin 11)?
Released into uterine fluid and may be involved in adhesion of blastocyst to endometrium
51
What occurs in Decidualisation?
Endometrial changes due to progesterone - glandular epithelial secretion - glycogen accumulation in stromal cell cytoplasm - growth of capillaries - increased vascular permeability (can lead to oedema)
52
What factors are involved in Decidualisation?
Interleukin-11 (IL-11) Histamine Certain prostaglandins TGFBeta (promotes angiogenesis)
53
What hormone rises at the beginning of pregnancy and is measure for in pregnancy tests?
hCG (Human chorionic gonadotropin) - can cause early symptoms of nausea and vomiting - hCG level falls after initial stages of pregnancy
54
Within what weeks of pregnancy does hCG rise and fall?
Rises = 0-8 weeks Falls = 8-12 weeks mainly = low levels until the end
55
Other than hCG, what hormones rise during pregnancy and remain higher than normal?
Human Placental Lactogen Oestrogens (mainly oestriol) Progesterone
56
What pregnancy-associated hormone rises to the highest level?
Progesterone Peak just before birth at 37 weeks approximately
57
What ion does Human Placental Lactogen balance within the body during pregnancy?
Calcium
58
Outline what happens in the first 40 days of pregnancy overall regarding progesterone and oestrogen production
FIRST 40 DAYS Hormones are produced in corpus luteum (in maternal ovary) - stimulated by hCG produced by trophoblasts - hCG acts on LH receptors Essential for developing foetoplacental unit Inhibits maternal LH and FSH via negative feedback
59
Outline what happens after 40 days of pregnancy overall regarding progesterone and oestrogen production
The placenta produces progesterone and oestrogen
60
Why are LH and FSH inhibited in pregnancy via negative feedback?
To prevent menstrual cycles during pregnancy
61
What do the mother and foetus both produce which leads to making oestrogens?
DHEAS
62
What are the physiological changes in maternal hormones during pregnancy?
INCREASE - ACTH - Cortisol - Adrenal Steroids - Prolactin - IGF1 (stimulated by placental GH-variant) - Iodothyronines - PTH Related Peptides - Placental GH - Kisspeptin DECREASE - Gonadotrophins (due to high circulating oestrogen) - Pituitary GH - TSH
63
Why can't cortisol or prolactin levels be used as diagnostic tools during pregnancy?
Because they are falsely raised as a result of pregnancy
64
What is the purpose of high kisspeptin during preganancy?
Synthesised and secreted by placenta Acts on GnRH neurones to stimulate reproductive axis Levels rise by 7000x - switches off reproductive axis - regulates invasion of placenta into endometrium
65
Where is Oxytocin secreted from?
Posterior Pituitary (Neurohypophysis)
66
What is the function of oxytocin during labour?
Oxytocin binds to oxytocin receptor on endometrial muscle This leads to contraction This then leads to parturition [These receptors increase in number during pregnancy]
67
What is parturition?
The action of giving birth to young; childbirth
68
Explain the endocrine mechanism that leads to lactation
Suckling = stimulus Neural pathways Hypothalamus Pituitary - adenohypophysis = prolactin (milk synthesis) - neurohypophysis = oxytocin (milk ejection)
69
Why can high prolactin levels cause amenorrhea in women and decreased libido in men?
It binds to kisspeptin receptors and switches off/downregulates the reproductive axis
70
What is the action of prolactin in lactation?
Milk synthesis
71
What is the action of oxytocin in lactation?
Milk ejection
72
What are the overall actions of oxytocin in pregnancy?
Cervical dilatation Milk ejection Uterine contraction
73
Why can marathon runners have high prolactin?
Their tops brush against their nipples causing stimulation of the neural pathways that lead to prolactin release.

Yr 2 LCRS - Endo (28 decks)

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