Physiology of Pregnancy and Puerperium Lactation Flashcards

1
Q

what is the role of the fimbriae?

A

sweep ovum into oviduct, carried along by smooth muscle contraction and cilia

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2
Q

what is a fertilised ovum called once it divides and differentiated?

A

blastocyst

*progressively divides into blastocyst as it moves from site of fertilisation in upper oviduct to site of implantation in uterus

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3
Q

between which days after fertilisation does the blastocyst attach to lining of uterus?

A

5-8

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4
Q

what do the inner cells and outer cells of blastocyst develop into?

A

inner cells = embryo

outer cells = burrow into uterine wall and become placenta

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5
Q

what is the role of the placenta?

A

produce several hormones to maintain pregnancy

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6
Q

what happens once the free-floating blastocyst adheres to the endometrial lining?

A

cords of trophoblastic cells begin to penetrate the endometrium

advancing cords of trophoblastic cells tunnel deeper into the endometrium, carving out a hole for the blastocyst

the boundaries between cells in the advancing trophoblastic tissue disintegrates

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7
Q

what is the decidua?

A

modified mucosal lining of the uterus (that is, modified endometrium) that forms in preparation for pregnancy.
*formed in a process called decidualization under the influence of progesterone

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8
Q

when implantation is finished, the blastocyst is completely buried in the endometrium - what day does this occur?

A

day 12

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9
Q

what type of tissue is the placenta derived from?

A

trophoblast and decidual tissue

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10
Q

how is the placenta formed?

A

trophoblast cells (chorion) differentiate into multinucleate cells (syncytiotrophoblasts) which invade decidua and break down capillaries to form cavities filled with maternal blood

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

each villus contains foetal capillaries separated from maternal blood by a thin layer of tissue (no direct contact between foetal and maternal blood)

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11
Q

the placenta acts as a 2 way exchange of what?

A

respiratory gases, nutrients, metabolites

largely down diffusion gradient

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12
Q

the placenta and foetal heart are functional by which week of pregnancy?

A

5th

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13
Q

what is the role of human chorionic gonadotrophin (HCG)?

A

signals the corpus luteum to continue secreting progesterone

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14
Q

what is the role of progesterone?

A

signal decidual cells to concentrate glycogen, proteins and lipids

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15
Q

where do blood vessels from the embryo develop?

A

villi (hair like projections) from placenta into uterine wall

*thin membrane separates the embryos blood in the villi from mothers blood in intervillous space

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16
Q

the circulation within the intervillous space acts partially as what?

A

arteriovenous shunt

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17
Q

what is the difference in components of maternal vs umbilical blood?

A

maternal = oxygen rich

umbilical blood = mixing of arterial and venous blood, oxygen-poor

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18
Q

how do oxygen and CO2 exchange between maternal and foetal circulation?

A

oxygen diffuses from maternal into foetal circulation (PO2 maternal > PO2 fetal)

CO2 (partial pressure is elevated in fetal blood) follows a reversed gradient

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19
Q

once oxygen and CO2 has been exchanged between maternal and fetal circulation, how does it return back?

A

fetal, oxygen saturated blood, returns to the fetus via the umbilical vein

maternal, oxygen-poor blood, flows back into the uterine veins

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20
Q

what three factors facilitate the supply of oxygen to the foetus?

A
  1. fetal Hb (increased ability to carry O2)
  2. higher Hb concentration in blood (50% more than in adults)
  3. bohr effect (foetal Hb can carry more oxygen in low PCO2 than in high PCO2)
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21
Q

how does water diffuse through the placenta?

A

along its osmotic gradient

*exchange increases during pregnancy up to 35th week (3.5l/day)

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22
Q

what follows H2O in the diffusion through the placenta?

A

electrolytes (iron and Ca2+ only can go from mother to child)

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23
Q

how does glucose (foetus’ main source of energy) pass the placenta?

A

via simplified transport (high glucose needed in 3rd trimester)

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24
Q

fatty acids have free diffusion - true or false?

A

true

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25
diffusion of waste products is based on what?
concentration gradient
26
what is the role of human chorionic gonadotropin?
prevents involution of corpus luteum (stimulates progesterone, oestrogen) *effect on testes of male foetus = development of sex organs
27
what is the role of human chorionic somatomammotropin?
produced from week 5 of pregnancy growth hormone-like effects = protein tissue formation decreases insulin sensitivity in mother = more glucose for foetus involved in breast development
28
what is the role of progesterone?
development of decidual cells decreases uterus contractility preparation of lactation
29
what is the role of oestrogens?
enlargement of uterus breast development relaxation of ligaments
30
what hormone acts as an indicator of vitality of the foetus?
estriol level
31
what is the consequences to the mother if the placenta produces CRH?
mother produces ACTH which increases aldosterone (hypertension) and cortisol (oedema and insulin resistance -> gestational diabetes)
32
what is the consequences to the mother if the placenta produces HC thyrotropin?
hyperthryoidism
33
what is the consequences to the mother if the placenta has increasing Ca2+ demands?
hyperparathyroidism
34
why does the mother have an increased cardiac output during pregnancy?
due to the demands of the uteroplacental circulation *as a result, ECG changes, functional murmurs and heart sounds are all normal changes
35
when in pregnancy does CO decrease again?
last 8 weeks (becomes sensitive to body position: uterus compresses vena cava) *increases 30% more in labour
36
what is the changes in heart rate and blood pressure during pregnancy?
HR increases up to 90/min to increase CO BP drops during 2nd trimester (uteroplacental circulation expands and peripheral resistance decreases)
37
with twins, does CO increase more or decrease?
increases more *BP drops more
38
what are the haemotological changes in mother in pregnancy?
PV increases proportionally with CO RBC increases Hb is decreased by dilution (decreases blood viscosity) iron requirements increase
39
how much iron is required during 2nd half of pregnancy?
6-7mg/day *iron supplements needed
40
why does maternal lung function change during pregnancy?
partly due to progesterone increase and partly due to enlarging uterus interfering with lung function
41
what maternal respiratory changes occur during pregnancy?
progesterone signals the brain to lower CO2 levels (increases CO2 sensitivity in resp centres) O2 consumption increases to meet need of foetus growing uterus
42
as a result of these respiratory changes, how does the body actually lower these CO2 levels?
resp rate increases tidal volume increases pCO2 decreases slightly *vital capacity and PO2 don't change
43
what maternal urinary system changes occur during pregnancy?
GFR and renal plasma flow increases increased re-absorption of ions and water (placental steroids, aldosterone) slight increase of urinary formation
44
how does postural changes affect renal functions in pregnancy?
upright position - decreases renal function supine position - increases renal function lateral position during sleep - increases renal functions
45
what is pre-eclampsia?
pregnancy induced hypertension and proteinuria
46
what changes take place in pre-eclampsia?
increasing BP since week 20 kidney function declines - salt and water retention (oedema formation esp in hands and face) renal blood flow and GFR decreases
47
pre-eclampsia is more common in what women?
those with - pre-existing hypertension - diabetes - autoimmune diseases - renal diseases - FH of pre-eclampsia - obesity - multiple birth most significant risk = having it before
48
what is thought to cause pre-eclampsia?
extensive secretion of placental hormones immune response to foetus insufficient blood supply to placenta
49
what is eclampsia?
extreme pre-eclampsia (lethal without treatment)
50
what are the signs of eclampsia?
vascular spasms extreme hypertension chronic seizures coma
51
what is the treatment of eclampsia?
vasodilators | C-section
52
what is the average weight gain during pregnancy?
24lb *can be as much as 75lb
53
how many extra calories should be ingested by mother during pregnancy?
250-300 extra protein intake = 30g/day
54
what are the 2 metabolic phases of pregnancy?
1st-20th week = mothers anabolic phase - anabolic metabolism of mother - increased sensitivity to insulin, lower plasma glucose, lipogenesis, glycogen stores increases - growth of breasts, uterus, weight gain - quite small nutritional demands of foetus 21st-40th week (esp last trimester) - high metabolic demands of foetus - insulin resistance, increased transport of nutrients through placental membrane, lipolysis - accelerated starvation of mother
55
during which metabolic phase of pregnancy does maternal insulin resistance take place?
catabolic (2nd) phase - caused by increased HCS, cortisol and growth hormone
56
what are the different special nutritional needs in pregnancy?
``` folic acid - reduces risk of neural tube defects vitamin D supplements high protein diet, higher energy uptake iron supplements may be required B-vitamins - erythropoesis ```
57
during parturition (birth), how does the oestrogen:progesterone ratio alter?
increases excitability - progesterone inhibits contractility while oestrogen increases contractility
58
what hormone from the maternal posterior pituitary gland increased contractions and excitability?
oxytocin *this stimulates uterus to contract and stimulates placenta to make prostaglandins from uterine wall which stimulates more vigorous contractions
59
what foetal hormones control timing of labour?
oxytocin adrenal gland hormones prostaglandin
60
other than hormones, what else increases uterus contractility and stimulates uterine contractions?
mechanical stretch of uterine muscles increases contractility stretch of cervix also stimulates uterine contractions
61
what positive feedback takes place during labour?
stretch of the cervix by foetal head increases contractility cervical stretching also causes further oxytocin release
62
how does uterine contractions induce intense abdominal muscle contractions?
strong uterine contractions and pain from birth canal cause neurogenic reflexes from spinal cord that induce intense abdominal muscle contractions
63
what are the three stages of labour?
``` 1st = cervical dilation (8-24 hours) 2nd = passage through birth canal (few min to 120 min) 3rd = expulsion of placenta ```
64
what is the role of oestrogen and progesterone in producing milk?
oestrogen = growth of ductile system progesterone = development of lobule-alveolar system
65
why is milk only produced at birth?
both oestrogen and progesterone inhibit milk production at birth, there is a sudden drop in these hormones
66
what hormone stimulates milk production?
prolactin (steady rise in levels week 5 - birth) 1-7 days after birth, prolactin induces high milk production stimulates colostrum (low volume, no fat)
67
how does sound of childs cry induce milk production?
sound causes hypothalamus to signal to pituitary to release prolactin (anterior pit) and oxytocin (posterior pit) which causes milk secretion and smooth muscle contraction the machoreceptors in nipple results in baby suckling