Physiology of pregnancy and lactation Flashcards

1
Q

Describe the changes seen as the ovum progresses from the ampulla to implantation?

A

Polar bodies form
Cleavage
Morula formed
Blastocyst

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2
Q

What is the difference between the inner cell mass and trophoblast?

A

Inner cell mass; destined to become foetus

Trophoblast; accomplishes implantation and develops into foetal portions of placenta

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3
Q

What occurs day 3-8 in fertilisation?

A

3-5; transport of blastocyst into uterus

5-8; blastocyst attaches to lining of uterus

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4
Q

How does the blastocyst implant on the endometrial wall?

A

When the free-floating blastocyst adheres to endometrial lining, cords of trophoblastic cells begin to penetrate the endometrium
Advancing cord of trophoblastic cells tunnel deeper into endometrium, carving out a hole for the blastocyst.
Boundaries between cells in advancing trophoblastic tissue disintegrate

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5
Q

When is the implantation completed?

A

Day 12

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6
Q

From what cells is the placental derived from?

A

Trophoblast

Decidual

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7
Q

What will trophoblast cells differentiate into?

A

Multinucleate cells (syncytiotrophoblasts) which invade the decidua and break down capillaries to form cavities filled with maternal blood

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8
Q

How does the placenta get a vascular supply?

A

Developing embryo sends capillaries into the syncytiotrophoblast projections to form placental villi

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9
Q

What does each villus contain?

A

Foetal capillaries separated from maternal blood by a thin layer of tissue

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10
Q

When is the placental and foetal heart functional?

A

Week 5

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11
Q

How does the embryo gain nutrition from the placenta?

A

Invasion of trophoblastic cells into the decidua

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12
Q

What will hCG stimulate?

A

Corpus luteum to continue to secrete progesterone

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13
Q

What is the function of progesterone in early pregnancy?

A

Stimulates decidual cells to concentrate glycogen, proteins and lipids

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14
Q

What occurs in terms of vasculature as the placenta develops?

A

It extends hair like projections into the uterine wall

Increasing contact area between uterus and placenta allowing for more nutrients to be exchanged

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15
Q

Where do blood vessels from the embryo develop?

A

In villi

A thin membrane separates the embryo’s blood in villi from mother’s blood in the intervillous space

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16
Q

Is there direct contact between maternal and foetal blood?

A

No; circulation within intervillous space acts partly as an arteriovenous shunt

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17
Q

What is the role of the placenta in oxygen transport?

A

Plays the role of foetal lungs

Supplies oxygen, removes carbon dioxide

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18
Q

How does maternal oxygen diffuse into foetal circulation?

A

The partial pressure of oxygen in mother is higher that foetus

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19
Q

How can carbon dioxide be removed from foetus?

A

Partial pressure is elevated in foetal blood to allow for a reversed gradient

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20
Q

Through which structure is foetal oxygenated blood returned to the foetus?

A

Umbilical vein

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21
Q

Through which structure is maternal oxygen poor blood returned?

A

Uterine vein

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22
Q

What 3 factors facilitate foetal oxygen supply?

A

Foetal Hb; increased ability to carry oxygen
Higher Hb; concentration in foetal blood is more than 50% of adults
Bohr effects; foetal Hb can carry more oxygen in low pCO2 than in high pCO2

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23
Q

What is the function of hCG?

A

Prevents involution of corpus luteum (stimulates progesterone, oestrogen)
Effect on testes of male foetus; development of sex organs

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24
Q

When is hPL produced?

A

Week 5 of pregnancy

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25
What is the function of hPL?
Growth hormone like effect; protein tissue formation Decreases insulin sensitivity in mother; more glucose for foetus Involved in breast development
26
Which hormones are responsible for the development of gestational diabetes in women?
Human placental Lactogen Cortisol Growth hormone
27
What is the function of progesterone in pregnancy?
Development of decidual cells Decreases uterine contractility Preparation for lactation
28
What is the function of oestrogen in pregnancy?
Enlargement of uterus Breast development Relaxation of ligaments
29
What should happen to hCG levels in pregnancy?
Should double every 48 hours in a singleton early pregnancy
30
For what conditions can hCG be used to diagnose/ monitor?
Ectopic; static or slow rising Failing pregnancy; falling Ongoing viable pregnancy; doubling or > 60% rise
31
What are the side effects of rising hCG in pregnancy?
Nausea Vomiting HYPEREMESIS GRAVIDARUM
32
When are high levels of hCG common?
Multiple pregnancy | Molar pregnancy
33
When should hCG levels peak and fall?
Peak; 8-12 weeks | Fall from 12-14 weeks then plateau
34
What is the role of CRH in pregnancy?
Increased ACTH Increased aldosterone and cortisol Hypertension and oedema + insulin resistance
35
What is the sequelae of increased hCG in pregnancy?
Hyperemesis gravidarum | Hyperthyroidism
36
What is the sequelae of increased calcium demands in pregnancy/?
Hyperparathyroidism
37
Does CO change in pregnancy?
Increased due to demands of uteroplacental circulation
38
How will CO change as the pregnancy progresses?
30-50% above normal from 6-24wks Decreases in last 8 weeks Increases by 30% in labour
39
What is the resultant effect of increased CO in pregnancy?
Placental circulation Increased metabolism Skin; thermoregulation Renal circulation
40
Will HR increase in pregnancy?
Yes; up to 90/min to increase CO
41
What occurs with BP in pregnancy?
Drops during 2nd trim (uteroplacental circulation expands and peripheral resistance decreases) With multiple pregnancies, CO increases more, BP drops more
42
What are the haematological changes assoc with pregnancy?
Plasma volume increases proportionally with CO Erythropoiesis increases by 25% Hb is decreased by dilution (decreasing blood viscosity) Iron requirements increase (6-7mg/day in 2nd trim)
43
Which hormone results in the resp changes seen in pregnancy?
Progesterone increases and enlarging uterus
44
What is the role of progesterone in resp changes in pregnancy?
Signals brain to lower co2 levels (increases co2 sensitivity in resp centres )
45
What are the 3 factors that change respiration in pregnancy?
Progesterone action on brainstem O2 consumption increases (20% above normal) Growing uterus
46
What are the mechanisms the body will adapt to lower co2 levels in pregnancy?
RR increases Tidal and minute volume increases (50%) pCO2 decreases slightly Vital capacity and pO2 don't change
47
Will GFR and renal plasma flow increase in pregnancy?
Yes; both increase up to 30-50% with a peak at 16-24 weeks
48
What is the resultant effect of increased GFR and renal plasma flow in pregnancy?
Increased re-absorption of ions and water Placental steroids Aldosterone Increased urine formation
49
What effect does posture have on renal function in pregnancy?
Upright position; decreased Supine; increased Lateral position in sleep; increased alot
50
What is preeclampsia?
Pregnancy induced hypertension and proteinuria
51
At what week can preeclampsia be diagnosed?
20th week
52
What happens to renal function in pre-eclampsia?
Declines; salt and water retention (oedema esp hands and face) Renal blood flow and GFR decrease
53
What are risk factors for pre-eclampsia?
``` Pre-existing hypertx Diabetes Autoimmune disease (lupus) Renal disease Family history of preeclampsia Obesity Women with multiple gestation ```
54
What is the single most significant risk for preeclampsia?
Previous pre-eclampsia
55
What causes pre-eclampsia?
Extensive secretion of placental hormones Immune response to foetus Insufficient blood supply to placenta; ischaemia
56
What is eclampsia?
Extreme pre-eclampsia which is lethal without treatment
57
What are the symptoms of eclampsia?
Vascular spasm Extreme hypertension Chronic seizures Coma
58
What is the treatment for eclampsia?
Vasodilators | C-section
59
What is the average maternal weight gain in pregnancy?
11kg; but can be as much as 30kg
60
What makes up the maternal weight gain?
``` Foetus; 3.5kg Extra-embryonic fluid/ tissue; 2 kg Uterus; 1kg Breast; 1kg Body fluid; 2.5kg Fat accumulation; 1kg ```
61
How should the diet of a mother change whilst pregnant?
200 kcal - 85% foteal metabolism, 15% stored as maternal fat 30g/day protein End of pregnancy; foetal glucose needs 5mg/kg/min therefore mother requires 2.5mg/kg/min
62
What is the 1st phase of pregnancy?
Weeks 1-20; mothers anabolic phase Anabolic metabolism of mother Small nutritional demands of conceptus
63
What is the 2nd phase of pregnancy?
21-40 weeks esp last trim High metabolic demands of foetus Accelerated starvation of mother
64
What occurs in the mothers anabolic phase?
Normal or increased sensitivity to insulin Lower plasmatic glucose level Lipogenesis, glycogen stores increased Growth of breasts, uterus, weight gain
65
What occurs in the mothers catabolic phase?
Maternal insulin resistance Increased transport of nutrients through placental membrane Lipolysis
66
What are the special nutritional needs in pregnancy?
``` Folic acid; reduces risk of neural tube defects Vit d; esp in overweight women High protein diet; higher energy uptake Iron supplements B vits - erythropoiesis ```
67
What hormone ratio changes resulting in increased excitability of uterus?
Oestrogen: prog | Progesterone inhibits contractility whilst oestrogen increases
68
What is the role of oxytocin in parturition?
Increases contraction and excitability
69
What hormones does the foetus produce?
Oxytocin Adrenal gland Prostaglandins
70
What stimulates uterine contraction?
Mechanical stretch of uterine muscles | Stretch of cervix - oxytocin release
71
When will women get braxton Hicks contractions?
Near end of pregnancy
72
What acts as a positive feedback mechanism in the onset of labour?
Stretch of cervix by foetal head increases contractility
73
What impact will strong uterine contraction have on the spinal cord?
Neurogenic reflexes that will induce intense abdominal muscle contractions
74
What is the effect of oestrogen on initiation of labour?
Induces oxytocin receptors on the uterus
75
What is the effect of oxytocin in initiation of labour?
Stimulates uterus to contact | Stimulates placenta to make prostaglandins
76
What is the effect of prostaglandins on initiation of labour?
Stimulates more vigorous contractions of the uterus
77
What is the 1st stage of labour?
Cervical dilation (8-24 hours)
78
What is the 2nd stage of labour?
Passage through birth canal (few mins to 120 mins)
79
What is the 3rd stage of labour?
Expulsion of placenta
80
What effect does oestrogen have on the production and release of milk?
Growth of ductile system
81
What effect does progesterone have on the production and release of milk?
Development of lobule-alveolar system
82
What effect does E and P have on milk production?
Inhibit At birth; sudden drop in E and P Oestrogen = growth of ductile system Progesterone = growth of lobules
83
What effect does prolactin have on the production and release of milk?
Stimulates milk production (steady rise in levels from wk 5 to birth) 1-7 days after birth, prolactin induces high milk production Stimulates colostrum
84
What are the components of colostrum?
High protein | High immunoglobulin allowing for foetal immunity
85
Which hormones are involved in the milk let down reflex?
Oxytocin | Prolactin