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Reproduction > Physiology of Pregnancy and Lactation > Flashcards

Physiology of Pregnancy and Lactation Flashcards

(86 cards)

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1
Q

summarise the stages of fertilisation from ovulation to implantation

A

fimbrae sweep ovum into oviduct, carried by smooth muscle contraction and cilia
fertilisation occurs in ampulla of fallopian tube (day 1)
cleavage, division and differentiation
morula
blastocyst containing inner cell mass (becomes fetus) and trophoblast (accomplishes implantation and develops into fetal portions of placenta)
blastocysts reaches uterus day 4-5 and implants days 5-7

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2
Q

how does implantation occur

A

cords of trophoblastic cells invade the endometrium
as they carve deeper into endometrium make hole for the blastocyst and the boundaries between the cells in the advancing trophoblastic tissue disintergrate
when implantation is finished the blastocyst is completely buried in the endometrium (day 12)

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3
Q

what happens to the different parts of the blastocyst

A 
inner cells become embyro 
outer cells (trophoblastic cells) burrow into endometrium and become the placenta
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4
Q

do maternal and foetal circualtions mix

A

no

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5
Q

what tissue is the placenta derived from

A

both trophoblast and decidual tissue (endometrium during pregnancy)

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6
Q

how is the placenta formed

A

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

developing embryo send capillaries into 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 bloods)

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7
Q

what gestation is the placenta functional

A

week 5

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8
Q

what exchange occurs at placenta

A

2 way exchange of resp gases, nutrients, metabolites

largely down diffusion gradient

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9
Q

what does hCG do to the corpus luteum

A

signals it to continue secreting progesterone

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10
Q

what does progesterone do to decidual cells

A

stimulates them to concentrate glycogen, proteins and lipids

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11
Q

as the placenta develops it extends villi into the uterine wall, what does this do

A

increases contact area between uterus and placenta meaning more nutrients and waste materials can be exchanged

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12
Q

what provides the early nutrition for the embryo

A

corpus luteum

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13
Q

what is the intervillous space and what is its function

A

within villi mothers blood is in intervillous soace along with blood vessels from the embryo. these re separated by a thin membrane

circulation within the intervillous space acts as an arteriovenous shunt (passage between artery and vein)

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14
Q

what structure acts as the fetal lungs

A

the placenta

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15
Q

what is the respiratory function of the placenta

A

supplies O2

removes CO2

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16
Q

how does the placental exchange of gas happen

A

maternal O2 rich blood
umbilical blood is a mix of arterial and venous blood, O2 poor
O2 diffuses from maternal into foetal circulation system (PO2 maternal> PO2 fetal)

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

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17
Q

what happens to the blood after placental gas exchange

A

O2 rich fetal blood returns to fetus via umbilical vein

maternal O2 low blood flows back into the uterine veins

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18
Q

how does the fetus receive sufficient oxygenation

A

fetal Hb has increased ability to carry O2
higher Hb concentration in fetal blood (50% more than in adults)
bohr effect (fetal Hb can carry more O2 in low pCO2 than in high pCO2)

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19
Q

how does water cross placenta

A

along its osmotic gradient (exchange increases during pregnancy up to 35th week)

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20
Q

how do electrolytes cross placenta

A

follow H20

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21
Q

which electrolytes can only go from mother to fetus and not back

A

iron and Ca2+ - why anaemia common in pregnancy

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22
Q

how does glucose cross placenta

A

(fetus’ main source of energy)
passes the placenta via simplified transport
(high glucose need in 3rd trimester)

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23
Q

how do fatty acids cross placenta

A

free diffusion

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24
Q

what is diffusion of waste products across placenta based on

A

concentration gradient

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25
what teratogenic drugs can cross the placenta
``` thalidomide carbamazepine coumarins tetracycline alcohol, nicotine, heroin, cocaine, caffeine ``` drugs (exclusing alcohol) cause 3% of all congenital malformations
26
what effect does hCG have
prevents involution of the corpus luteum | affect on the testes of the male fetus (development of sex organs)
27
when does hCG peak
8-12 weeks
28
what is the role of human placental lactogen
produced from week 5 of pregnancy growth hormone like effects - protein tissue formation decreases insulin sensitivity in mother- more glucose for the fetus involved in breast development
29
what is the role of progesterone in pregnancy
development of decidual cells decreases uterus contractility- makes uterus relax preparation for lactation
30
what are the forms of oestrogen that are secreted in higher volumes as pregnancy progresses
estradiol (most secreted) estriol estrone
31
what is the role of estrogens in pregnancy
enlargement of uterus breast development relaxation of ligaments
32
what can relaxation of ligaments in pregnancy cause
pelvic girdle pain
33
how do hCG levels increase in a normal pregnancy
should double (or increase by >60%) every 48 hours in a singleton early pregnancy
34
what can hCG levels be used to help diagnose
``` ongoing viable pregnancy (doubling, or >60% rise) ectopic pregnancy (static or slow rising) failing pregnancy (falling) ```
35
what are the side effects of hCG
nausea and vomiting
36
what can cause high levels of hCG
multiple pregnancy | molar pregnancy
37
when do hCG levels start to fall
from 12-14 weeks
38
what does placental release of CRH (corticotrophin releasing hormone) cause
``` ACTH release in mother increase aldosterone (=hypertension) and cortisol (= oedema and insulin resistance = gestational diabetes) ```
39
what does HCG (HC thryotropin) released from the placenta cause
hyperthyroidism in the mother
40
what does increased Ca2+ demands of the placenta cause
hyperparathyroidism in the mother
41
what happens to cardiac output in pregnancy
is increased by 30-50% (begins 6wk gestation and peaks at 24 wks) due to demands of the uteroplacental circulation decreases in last 8 weeks (becomes sensitive to body position, uterus compresses vena cava) increases 30% more during labour
42
what causes the cardiac output to increase in pregnancy
placental circulation increased metabolism skin thermoregulation renal circulation
43
what can the increase CO cause in pregnant mothers
``` ECG changes functional murmurs (usually mild systolic and normal but always investigate) heart sounds ```
44
what happens in HR in pregnancy
increases with to 90/min to increase cardiac output
45
what happens to BP in pregnancy
drops during 2nd trimester (uteroplacental circulation expands and peripheral resistance decreases - vasodilation) with multiple pregancies cardiac output increases more and BP drops lower lowest at 17-24 wks, rises after this back to normal (36wks) then can go higher than BP before pregnancy
46
what haematologic changes happen in pregnancy
plasma volume increases proportionally with cardiac output (50%) erythropoesis (RBC) increases (25%) Hb is decreases by dilution (this decreases blood viscosity) iron requirements increase significantly (6-7 mg/ day in 2nd trim)- supplements usually needed
47
why lung changes happen in pregnancy
increase in progesterone (signals brain to lower CO2 levels) | enlarging uterus interferes with lung function - works to lower CO2
48
how does progesterone lower CO2 levels
increases CO2 sensitivity in respiratory centres of brain
49
what happens in O2 consumption in pregnancy
increases to meet metabolic needs of fetus, placenta and mother (20% above normal)
50
how is CO2 physically reduced in pregnancy
RR increases tidal and minute volume increases (50%) pCO2 decreases slightly vital capacity and PO2 dont change
51
what happens to the urinary system in pregnancy
GFR and renal plasma flow increase (up to 30-50%, peaks at 16-24 wks) increased re-absorption of ions and water (due to placental steroids and aldosterone) slight increase in urine formation
52
how do postural changes affect renal function
when in: up right position renal function decreased supine position increased lateral position during sleep increased significantly
53
what is pre-eclampsia
pregnancy induced hypertension and proteinuria
54
what are the features of pre-eclampsia
increasing BP since 20th week- hypertension kidney function declines causing salt and water retention- oedema of face and hands renal blood flow and GFR decreases
55
what causes pre eclampsia
?extensive secretion of placental hormones ?immune response to fetus insufficient blood supply to placenta- ischaemia
56
who is pre-eclampsia more common in
women with pre existing hypertension, diabetes, autoimmune disease (e.g. lupus), renal disease, FHx of pre-eclampsia, obesity, multiple gestations (twins)
57
what is eclampsia
extreme pre-eclampsia (lethal without Tx) | vascular spasms, extreme hypertension, chronic seizures and coma
58
what is the treatment for eclampsia
vasodilation and cesarean section
59
what is the average maternal weight gain (and what causes it )
11 kg - fetus (3.5 kg) - extra-embryonic fluid/ tissues (2 kg) - uterus (1 kg) - breasts (1 kg) - body fluid (2.5 kg) - fat accumulation (1 kg)
60
how much extra food is needed in pregnancy
200 extra calories/ day 30g/ day or protein end of pregnancy fetus needs 5mg/kg/min of glucose= 2.5mg/kg/min for mother
61
what causes the increased metabolic demand in pregnancy
85% fetal metabolism | 15% stored as maternal fat
62
what are the 2 metabolic phases of pregnancy
1st-20th week= mothers' anabolic phase: - anabolic metabolism of mother - small nutritional demands of the conceptus 21st-40th week (esp last trim) catabolic stage - high metabolic demands of fetus - accelerated starvation of mother
63
why should starvation of mother be avoided in pregnancy
as circulating ketones bad for babies brain
64
what happens physiologically in the anabolic phase of pregnancy
- normal/ increased sensitivity to insulin - lower plasmatic glucose level - lipogenesis, glycogen stores increase - growth of breasts, uterus, weight gain
65
what happens physiologically in the catabolic phase of pregnancy (accelerated starvation)
- maternal insulin resistance - increased transport of nutrients through placental membrane - lipolysis
66
what causes insulin resistance in pregnancy
HPL, cortisol and growth hormone
67
what are the special nutritional needs in pregnancy
folic acid- reduces risk of neural tube defects, ideally taken before conception vit D supplements (esp if mother overweight) high protein diet (higher energy intake) iron supplements may be required B vitamins for erythropoesis
68
towards the end of pregnancy the uterus progressively becomes more excitable- what does this mean
it becomes more contractile | progesterone inhibits contractility of uterus while oestrogen increases it
69
how does the uterus become more excitable during end of pregnancy
estrogen: progesterone ratio changes progesterone inhibits contractility of uterus while oestrogen increases it oxytocin (from maternal posterior pituitary gland) increases contractions and excitability mechanical stretch of uterine muscles and cervix by fetal head increases contractility
70
where is oxytocin release from
fetus | mothers posterior pituitary
71
what controls the timing of labour
oxytocin adrenal glands prostaglandins
72
what are braton hicks contractions
infrequent, irregular contractions that involve only mild cramping- preparing for birth, false labour become more frequent and stronger then labour pains begin
73
what does cervical stretching cause the release of
oxytocin
74
what do strong uterine contractions and pain from the birth canal cause
neurogenic reflexes from spinal cord that induce intense abdominal muscle contractions
75
what is parturition
initiation of labour
76
what hormone induces oxytocin receptors on uterus
estrogen
77
what does oxytocin cause
uterine contractions | stimulates placenta to make prostaglandins
78
what do prostaglandins cause
more vigorous contractions of uterus
79
what is full dilation
10 cm
80
what can induce labour
vaginal prostaglandins and oxytocin injection | intracervical ballon/ sweep- mechanical stretch
81
what are contractions like in late labour
strong, 3-4 every 10 minutes
82
what are the stages of labour
1st- cervical dilation (8-24 hours) 2nd- passage through birth canal (few mins to 120 mins) 3rd- expulsion of placenta
83
how does estrogen affect production and release of milk
stimulates growth of ductile system | inhibit milk production
84
how does progesterone affect production and release of milk
development of lobule-alveolar system | inhibit milk production
85
how does prolactin affect production and release of milk
stimulates milk production steady rise in weeks 5-birth) 1-7 days after birth prolactin induces high milk production stimulates colostrum (low volume, not fat- high in protein and immunoglobulins for fetal immunity)
86
what is the milk let down reflex
suckling stimulus (mechanoreceptors in nipple) or the sound of a childs cry causes release of prolactin (makes more milk) and oxytocin (causes breast to push out milk via smooth muscle contraction)

Reproduction (51 decks)

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