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brs (phase 1a) > (endo) pregnancy > Flashcards

(endo) pregnancy Flashcards

1
Q

in males, what occurs in the efferent ducts in the reproductive tract?

A

tubular fluid reabsorption resulting in concentration of fluid, which helps w male fertility

(induced by oestrogen)

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2
Q

in males, what occurs in the epididymis in the reproductive tract?

A

secretion of nutrients (e.g. fructose) and glycoprotein into the epididymal fluid

(induced by androgens)

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3
Q

what are the implications of aromatase deficiency?

A

(very rare!)

= hirsutism, acne, deep voice, primary amenorrhoea, tall (as need E2 to close epiphyseal growth plates), osteoporosis, virilisation of fetus

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4
Q

why is the secretion of nutrients into the epididymal fluid important in men?

A

fructose = provides an energy source for sperm to make their journey through the female reproductive tract

glycoprotein = preotective coating for sperm as they enter a hostile environment

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5
Q

what are the components of semen?

A

1) spermatozoa (15-120 million)
2) seminal fluid (2-5ml)
3) leukocytes

4) potentially viruses e.g. hepatitis B, HIV

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6
Q

what are the contents of seminal fluid?

A
  • fructose
  • fibrinogen
  • fibrinolytic enzymes
  • citric acid
  • bicarbonate
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7
Q

where is seminal fluid secreted from?

A

accessory sex glands

  • seminal vesicles
  • prostate gland
  • bulbourethral gland

small contribution from
- testis/epididymis

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8
Q

what is sperm capacitation?

A

the process of achieving fertilising capability in the female reproductive tract

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9
Q

what is involved in the capacitation of sperm?

A

1) loss of glycoprotein coat
2) changes in surface membrane characteristics
3) development of whiplash movements of the tail

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10
Q

where does capacitation of sperm occur?

A

takes place ONLY in the ionic & proteolytic environment of the fallopian tubes

(i.e. nowhere else in the male reproductive tract/initial parts of the female reproductive tracts)

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11
Q

what is sperm capacitation dependent on?

A

1) oestrogen-dependent

2) Ca2+-dependent

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12
Q

how many chromososme are found in one sperm?

A

23 chromosomes

= haploid

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13
Q

what is the acrosome?

A

organelle within sperm containing enzymes

= can bind to the zona pellucida

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14
Q

what is the zona pellicida?

A

glycoprotein layer surrounding the plasma membrane of the oocyte

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15
Q

explain what happens in the acrosome reaction

A

1) sperm bind to the ZP3 receptor (‘sperm receptor’) of the zona pellucida
2) Ca2+ influx into the sperm (stimulated by progesterone)
3) release of hyaluronidase and proteolytic enzymes from the acrosome

= sperm penetrates the zona pellucida and enters the oocyte

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16
Q

which receptor does the sperm bind to on the oocyte?

A

ZP3 receptor of the zona pellucida

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17
Q

what stimulates the calcium influx into the sperm during the acrosome reaction?

A

progesterone

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18
Q

why are hyaluronidase and proteolytic enzymes released from the acrosome?

A

to break down polysaccharides in the zona pellucida

= to allow sperm to enter the oocyte to enable fertilisation & fusion of gametes

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19
Q

where does fertilisation occur?

A

within the ampulla of the fallopian tube

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20
Q

what does fertilisation subsequently trigger?

A

the cortical reaction

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21
Q

what is the cortical reaction?

A

following fertilisation (i.e. once the sperm enters the egg), cortical granules release molecules that degrade the zona pellucida (e.g. ZP2 & 3)

= to prevent polyspermy

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22
Q

where are cortical granules found and why are they important?

A

in the oocyte

= release molecules upon fertilisation to degrade the zona pellucida
= so no polyspermy w no available receptors

23
Q

as the conceptus travels down the fallopian tube to the uterus, how does it receive its nutrition?

A

receives nutrients from uterine secretion

= during the 3-4 days it takes to travel from the fallopian tube to the uterus

24
Q

what are the two phases of implantation?

A

1) attachment phase

2) decidualisation phase

25
Q

what is the attachment phase of implantation?

A

outer trophoblast cells contact uterine surface epithelium

26
Q

what is the decidualisation phase of implantation?

A

changes in the underlying uterine stromal tissue

27
Q

what does implantation require?

A

requires progesterone domination in the presence of oestrogen

= as progesterone ‘PROmotes GESTATION’ and prepares endometrium for implantation

28
Q

which three molecules promote implantation?

A

LIF & IL11

(LIF = leukaemia inhibitory factor)

= + need progesterone (!!!!)

29
Q

what is the function of LIF in implantation?

A

produced by endometrial cells, LIF stimulates adhesion of blastocyst to the endometrial cells

30
Q

which cells produce LIF?

A

endometrial cells

31
Q

which cells produce IL11?

A

endometrial cells (release into uterine fluid)

32
Q

how do hCG levels change during pregnancy and why?

A

highest in the initial 10 weeks, and then fall to lower levels rapidly for remainder

= initially high as syncitiotrophoblast cells produce hCG to maintain CL production of progesterone + oestrogen (in the absence of an actual placenta)

33
Q

how do oestrogen levels change during pregnancy and why?

A

rise continuously

= produced initially by the corpus luteum and then the placenta (but to a lesser degree compared to progesterone production)

34
Q

how do progesterone levels change during pregnancy and why?

A

rise continuously

= produced initially by the corpus luteum and then the placenta (but to a greater degree compared to oestrogen production)

35
Q

what is human placental lactogen?

A

hormone made by the placenta that modulates maternal metabolism to provide nutrients for the foetus

e.g. causes insulin resistance to increase glucose bioavailability for foetus

36
Q

how does human placental lactogen work?

A

modulates maternal metabolism to provide nutrients for foetus

e.g. causes insulin resistance to increase circulating glucose for foetus

37
Q

how do human placental lactogen levels change during pregnancy?

A

rise continuously

but to a lesser degree compare to oestrogen and progesterone

38
Q

what controls progesterone and oestrogen production in the first 40 days of a pregnancy?

A

produced by the corpus luteum (of the maternal ovary)

= stimulated by hCG (produced by syncitiotrophoblast cells) which acts on the LH receptors

39
Q

what maintains the corpus luteum?

A

either LH or hCG

= both which act on LH receptors to prevent CL degradation

40
Q

what is the impact of oestrogen and progesterone secretion during pregnancy?

A

inhibits maternal LH & FSH via negative feedback loops

41
Q

what controls progesterone and oestrogen production AFTER the first 40 days of a pregnancy?

A

placenta takes over

i.e. luteo-placental shift

42
Q

from where does the placenta produce progesterone?

A

from maternal cholesterol converted into pregnenolone

43
Q

from where does the placenta produce oestrogen?

A

either from maternal or fetal DHEAS

1) maternal DHEAS = oestrone, oestradiol
2) fetal DHEAS = oestriol

44
Q

in pregnancy, which maternal hormones increase in concentration?

A
  • ACTH
  • adrenal steroids
  • prolactin
  • IGF-1 (stimulated by a placental GH-variant)
  • iodothyronines
  • PTH related peptides
45
Q

in pregnancy, which maternal hormones decrease in concentration?

A
  • gonadotrophins (LH, FSH)
  • pituitary GH
  • TSH
46
Q

why do iodothyronines increase in pregnancy?

A

hCG, made by the syncitiotrophoblast cells of the placenta, is similar to TSH

= mild stimulation of the thyroid gland to produce more thyroid hormone

47
Q

why do PTH-related peptides increase in pregnancy?

A

produced mainly by breast tissue

= can increase calcium for fetal skeleton

48
Q

why does IGF-1 increase in pregnancy?

A

placental GH secretion increases that stimulates the liver to secrete more IGF-1

49
Q

why do gonodotrophins fall in pregnancy?

A

during pregnancy, oestrogen + progesterone levels rise

= so, via negative feedback LH + FSH fall

50
Q

why does pituitary GH fall in pregnancy?

A

placenta releases placental GH and so pituitary GH levels fall via negative feedback

51
Q

why does TSH fall in pregnancy?

A

in pregnancy, hCG released by the placenta is similar to TSH and so stimulates the thyroid gland to secrete iodothyronines

= resulting in TSH levels falling bc of negative feedback

52
Q

what are the functions of oxytocin in females?

A

1) uterine contraction (increased oxytocin receptors in late pregnancy)
2) cervical dilation
3) milk ejection

53
Q

where are oxytocin receptors mainly found?

A

1) myoepithelial cells of the mammary gland

2) myometrium + endometrium of the uterus

54
Q

explain the endocrine control of lactation

A

stimulus = suckling of breast

suckling stimulates neural pathways that activate the hypothalamus + pituitary gland to release hormones

1) APG releases prolactin = milk PRODUCTION
2) PPG releases oxytocin = milk EJECTION

brs (phase 1a) (7 decks)

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