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Reproduction > Physiology of Pregnancy and Lactation > Flashcards

Physiology of Pregnancy and Lactation Flashcards

1
Q

What part of the blastocyst develops into the placenta?

A

Trophoblast = accomplishes implantation and develops into foetal portions of placenta

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2
Q

What happens to the fertilised ovum as it moves from the site of fertilisation to the site of implantation?

A

Progressively divides and differentiates into a blastocyst

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3
Q

Where does fertilisation occur?

A

In the ampulla of the fallopian tube

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4
Q

What happens to the blastocyst between days 3-5?

A

Transported into uterus

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5
Q

When does the blastocyst attach to the lining of the uterus?

A

From days 5-8

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6
Q

What do the different cells of the blastocyst develop into?

A

Inner cells = embryo

Outer cells = burrow into uterine wall and become placenta

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7
Q

What happens when the blastocyst adheres to the endometrial lining?

A

Cords of trophoblastic cells begin to penetrate the endometrium

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8
Q

What carves a hole in the endometrium for the blastocyst to adhere to?

A

Advancing cords of trophoblastic cells = tunnel deeper into endometrium

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9
Q

What happens to the boundaries between cells in advancing trophoblastic tissue?

A

The boundaries disintegrate

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10
Q

What is the fate of the blastocyst at the end of implantation?

A

It is completely buried in the endometrium = occurs by day 12

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11
Q

What is the placenta derived from?

A

Trophoblastic and decidual tissue

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12
Q

What do trophoblastic chorion cells differentiate into?

A

Multinucleate cells called syncytotrophoblasts = invade decidua and break down capillaries to form cavities filled with maternal blood

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13
Q

How are placental villi formed?

A

Developing embryo sends capillaries into the syncytotrophoblast projections

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14
Q

What does each placental villi contain?

A

Foetal capillaries separated from maternal blood by a thin layer of tissue = no direct contact between foetal and maternal blood

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15
Q

What kind of exchange exists between the mother and foetus?

A

2 way exchange = largely down diffusion gradient

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16
Q

When are the placenta and foetal heart functional from?

A

By the fifth week of pregnancy

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17
Q

What does HCG signal the corpus luteum to do?

A

Continue secreting progesterone = stimulates decidual cells to concentrate glycogen, proteins and lipids

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18
Q

What is the purpose of the placental villi?

A

Increase contact between uterus and placenta = more nutrients and waste products cane be exchanged

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19
Q

Where do blood vessels from the embryo develop?

A

In the placental villi = thin membrane separates embryonic villous blood from maternal blood in intervillous space

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20
Q

What does the circulation within the intervillous space act as?

A

An AV shunt

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21
Q

How does the placenta act as the foetal lungs?

A

Respiratory function makes supply of oxygen and removal of carbon dioxide possible

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22
Q

Where does exchange of oxygen take place in the placenta?

A

Between maternal oxygen-rich blood and umbilical oxygen-poor blood

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23
Q

What direction does oxygen move in during placental exchange?

A

From maternal into foetal circulation system = carbon dioxide moves in the opposite direction

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24
Q

What happens to blood once oxygen exchange has occurred within the placenta?

A

Foetal oxygen-enriched blood returns to foetus via umbilical vein
Maternal oxygen-depleted blood flows back into uterine veins

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25
Q

What facilitates foetal oxygen supply?

A

Foetal Hb = increased ability to carry oxygen
Higher Hb concentration = 50% higher than adults
Bohr effect

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26
Q

How does the Bohr effect facilitate foetal oxygen supply?

A

Foetal Hb can carry more oxygen in low pCo2 than in high pCO2

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27
Q

How is water transported in the placenta?

A

Diffuses into placenta along osmotic gradient = exchange increases during pregnancy up to 35th week (3.5L/day)

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28
Q

How are electrolytes transported in the placenta?

A

Follow water = iron and calcium only go from mother to child

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29
Q

How does glucose pass into the placenta?

A

By simplified transport = high demand in third trimester

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30
Q

How do fatty acids move in the placenta?

A

Via diffusion

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31
Q

What is diffusion of waste products based on?

A

Concentration gradient

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32
Q

How much are drugs (other than alcohol) implicated in congenital malformations?

A

Responsible for 3% of all congenital malformations

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33
Q

What is the function of HCG?

A

Peaks at 10 weeks gestation = prevents involution of corpus luteum, causes development of male sexual organs

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34
Q

What is the function of human placental lactogen (HPL)?

A

Produced from 5th week and increases as pregnancy goes on = GH-like effect causing protein tissue formation, decreases insulin sensitivity in mother, involved in breast development

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35
Q

What is the function of progesterone?

A

Increases as pregnancy goes on = development of decidual cells, decreases uterine contractility, preparation for lactation

36
Q

What are the functions of oestrogens?

A

Enlargement of uterus, breast development, relaxation of ligaments

37
Q

How do HCG levels change in a singleton early pregnancy?

A

Serum levels double every 48hrs

38
Q

What conditions can HCG levels be useful for diagnosis?

A

Ectopic pregnancy = static or slow rising levels
Failing pregnancy = falling levels
Ongoing viable pregnancy = doubling/>60% rise

39
Q

What are the side effects of HCG?

A

Nausea and vomiting

40
Q

When may high levels of HCG occur?

A

In multiple or molar pregnancies

41
Q

When do HCG levels begin to fall?

A

From 12-14 weeks gestation

42
Q

Why does cardiac output increase during pregnancy?

A

Due to the demands of the uteroplacental circulation

43
Q

How does the cardiac output change during pregnancy?

A

Increases to 30-50% above normal = begins in week 6 and peaks at week 24
Decreases in last 8 weeks = uterus compresses IVC
Increases 30% more during labour

44
Q

What are some normal CV changes that occur during pregnancy?

A

ECG changes, functional murmurs and heart sounds

45
Q

What happens to maternal heart rate during pregnancy?

A

Increases up to 90 beats per minute

46
Q

How does blood pressure change during pregnancy?

A

Drops during 2nd trimester = uteroplacental circulation expands and peripheral resistance decreases

47
Q

What are the CV changes that occur during a multiple pregnancy?

A

Cardiac output increases by more and BP drops by more than would occur during a singleton pregnancy

48
Q

What haematologic changes occur during pregnancy?

A

Plasma volume increases proportionally with cardiac output (50% increase)
Erythropoesis increases by 25%

49
Q

What effect do the haematologic changes that occur during pregnancy have on haemoglobin?

A

Decreases Hb by dilution = decreases blood viscosity

50
Q

How do iron requirements change during pregnancy?

A

Increase = 6-7 mg/day needed in second half of pregnancy = may need iron supplements

51
Q

What causes lung changes during pregnancy?

A

Increases in progesterone and the enlarging uterus interfering with lung function

52
Q

How does progesterone affect CO2 level?

A

Signals brain to lower CO2 levels

53
Q

Why does oxygen consumption increase during pregnancy?

A

Increases up to 20% above normal to meet metabolic needs of mother, foetus and placenta

54
Q

What changes occur to lower CO2 levels?

A

Respiratory rate increases, tidal and minute volumes increase, pCO2 increases slightly

55
Q

What changes occur in the urinary system during pregnancy?

A

GFR and renal plasma flow increase by up to 30-50% = peaks at 16-24 weeks gestation
Increased reabsorption of ions and water
Slight increase in urine formation

56
Q

How do postural changes during pregnancy affect renal function?

A

Decrease in function if upright
Increase in function if supine
Significant increase in function when in lateral position during sleep

57
Q

What is pre-eclampsia?

A

Pregnancy induced hypertension and proteinuria

58
Q

What are some signs of pre-eclampsia?

A

Increasing BP since 20 weeks gestation
Decrease in renal blood flow and GFR
Oedema = salt and water retention

59
Q

What causes oedema in pre-eclampsia?

A

Decline in renal function

60
Q

What are the risk factors for pre-eclampsia?

A

Pre-existing hypertension, diabetes, autoimmune disease, renal disease, family history, obesity, twins/multiple births

61
Q

What are the features of eclampsia?

A

Lethal without treatment = vascular spasms, extreme hypertension, chronic seizures, coma

62
Q

How is eclampsia treated?

A

C-section and vasodilators

63
Q

What is the usual maternal weight gain during pregnancy?

A

Average is 11kg = can be as much as 30kg

64
Q

What contributes to maternal weight gain during pregnancy?

A 
Foetus = 3.5kg
Extra-embryonic fluid and tissues = 2kg
Uterus = 1kg
Breasts = 1kg
Body fluid = 2.5kg
Fat accumulation = 1kg
65
Q

How much should calorie intake increase by during pregnancy?

A

200 extra kcal/day = 85% for foetal metabolism, 15% stored as maternal fat

66
Q

How does protein intake need to change during pregnancy?

A

Extra protein intake required = 30g/day

67
Q

When is the anabolic phase of pregnancy?

A

Weeks 1-20 = anabolic metabolism of mother, quite small nutritional demands of conceptus

68
Q

When is the catabolic phase of pregnancy?

A

Weeks 21-40 = especially high during 3rd trimester, high metabolic needs of foetus, accelerated starvation of mother

69
Q

What changes occur during the anabolic phase of pregnancy?

A

Normal/increased sensitivity to insulin
Lower plasma glucose level
Lipogenesis and increased glycogen stores
Growth of breasts and uterus, and weight gain

70
Q

What changes occur during the catabolic phase of pregnancy?

A

Maternal insulin resistance
Increased transport of nutrients through placental membrane
Lipolysis

71
Q

What causes insulin resistance?

A

HPL, cortisol and GH

72
Q

What are the special nutritional needs of pregnancy?

A

Folic acid = reduces risk of neural tube defects
High protein diet
Vitamin D and iron supplements
B vitamins = erythropoesis

73
Q

What happens to the uterus towards the end of pregnancy?

A

Becomes progressively more excitable

74
Q

What causes increased uterine excitability?

A

Alteration of oestrogen:progesterone ratio

Oxytocin = also increases contractions

75
Q

How do foetal hormones influence labour?

A

Control timing of labour

76
Q

What effect does stretch of pelvic organs during labour have?

A

Mechanical stretch of uterine muscles increases contractility
Stretch of cervix stimulates uterine contractions

77
Q

When do Braxton Hicks contractions occur?

A

Increase towards end of pregnancy

78
Q

How does positive feedback influence onset of labour?

A

Stretch of cervix by foetal head increases contractility and causes further oxytocin release

79
Q

What effect do string uterine contractions and pain from birth canal during labour have?

A

Cause neurogenic reflexes from spinal cord that induce abdominal muscle contractions

80
Q

What are the stages of labour?

A

1st stage = cervical dilation (8-24hrs)
2nd stage = passes through birth canal (up to 120mins)
3rd stage = expulsion of placenta

81
Q

How do oestrogen and progesterone aid lactation?

A 
Oestrogen = growth of ductile system
Progesterone = development of lobule-alveolar system
82
Q

What effect do oestrogen and progesterone have on milk production?

A

Inhibit milk production = drop suddenly at birth

83
Q

What hormone stimulates milk production?

A

Prolactin = steady rise in levels from week 5 to birth

84
Q

When does prolactin induce high milk production?

A

1-7 days after birth = also stimulates colostrum (low volume, no fat)

85
Q

What are the components of the milk let-down reflex?

A

Sucking stimulus and oxytocin

86
Q

What occurs in the milk let-down reflex?

A

Receptors in nipples stimulated
Impulses propagated to spinal cord
Stimulation of hypothalamic nuclei
Oxytocin released and milk ejected

Reproduction (62 decks)

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