Physiology - Pregnancy and Lactation Flashcards
1
Q
what does the fertilised ovum divide and become?
A
a blastocyst
2
Q
what occurs in the first 3-5 days following fertilisation?
A
transport of the blastocyst into the uterus
3
Q
what happens 5-8 days post fertilisation?
A
the blastocyst attaches to the lining of the uterus
4
Q
what do the inner cells of the blastocyst become?
A
the embryo
5
Q
what do the outer cells of the blastocyst become?
A
the placenta
6
Q
what happens when the blastocyst adheres to the endometrium?
A
cords of trophoblastic cells begin to penetrate the endometrium
7
Q
when is implantation of the blastocyst completed?
A
by day 12
8
Q
what is the placenta derived from?
A
trophoblasts
decidual tissue
9
Q
what is another name for the trophoblast cells?
A
chorion
10
Q
what do the trophoblast cells differentiate into?
A
multinucleate cells called synctiotrophoblasts
11
Q
what do the syncytiotrophoblast cells do?
A
invade the decider and break down capillaries, forming cavities filled with maternal blood
12
Q
what forms the placental villi?
A
capillaries from the developing embryo entering the syncytiotrophoblast projections in the decider
13
Q
what do placental villi contain?
A
foetal capillaries separated from maternal blood by a thin layer of tissue
14
Q
when are the placenta and foetal heart functional?
A
by the fifth week of pregnancy
15
Q
what provides early nutrition to the embryo?
A
trophoblastic cells that have invaded into the decidua
16
Q
what takes over providing nutrition to the embryo later in the pregnancy?
A
the placenta
17
Q
what effect does HCG have on the corpus luteum?
A
signals it to keep secreting progesterone
18
Q
what effect does progesterone have on the decidual cells?
A
stimulates them to concentrate glycogen, proteins and lipids
19
Q
what is the outcome of the placental villi extending into the uterine wall?
A
increases contact area between the uterus and placenta allowing gate exchange of nutrients and waste
20
Q
what plays the role of the foetal lungs?
A
the placenta - allows supply of oxygen and removal of CO2 from the foetus
21
Q
which has higher oxygen concentration - maternal or foetal blood?
A
maternal
22
Q
in which direction does oxygen diffusion in the placenta occur?
A
from the maternal circulation to the foetal circulation
PO2 maternal > PO2 foetal
23
Q
in which direction does CO2 diffusion occur in the placenta?
A
from the foetal circulation to the maternal circulation
maternal CO2 < foetal CO2
24
Q
where does foetal blood go after getting oxygen from the placenta?
A
returns to the foetus via the umbilical vein
25
where does maternal blood go after giving oxygen to the placenta?
back into the uterine veins
26
what three factors facilitate the supply of the foetus with oxygen?
foetal Hb
higher Hb concentration in foetal blood
Bohr effect
27
how is foetal Hb different from adult Hb?
has an increased ability to carry oxygen
28
which has a higher Hb concentration - foetal blood or maternal blood?
foetal
this enables greater oxygen transport
29
how does the Bohr effect facilitate oxygen transport in the foetus?
foetal Hb can carry more oxygen in low pCO2 than in high pCO2
this is good because foetal CO2 < maternal CO2
30
in which direction does water travel across the placenta and via what mechanism?
from mother to foetus
via osmosis
31
what amount of water is exchanged across the placenta in pregnancy?
increases up to the 35th week where it is around 3.5L per day
32
how do electrolytes cross the placenta?
follow the water that moves via osmosis
33
which electrolytes go ONLY from mother to child across the placenta?
iron and calcium
need to ensure mothers have adequate levels of these substances
34
how does glucose pass across the placenta?
via simplified transport
35
what is the foetuses main source of energy?
glucose
36
at which point in pregnancy is most glucose required?
in the third trimester
37
how do fatty acids move across the placenta?
via free diffusion
38
name four hormones that change throughout pregnancy
HCG
HCS/HPL
oestrogen
progesterone
39
what does HCG stand for?
human chorionic gonadotrophin
40
what does HCG do?
prevents involution of the corpus luteum
this stimulates progesterone and oestrogen production
41
what effect does HCG have on male foetuses?
aids in the development of the sex organs
42
describe the levels of HCG throughout pregnancy
highest in early pregnancy
43
what is another name for human placental lactogen (HPL)?
human chorionic somatomammotropin
44
when is HPL produced?
from around week 5 in pregnancy
continues to rise throughout pregnancy
45
what are the three main effects of HPL?
growth hormone like effects - protein tissue formation
decreases maternal insulin sensitivity
involved in breast development
46
what effect does decreasing insulin sensitivity in the mother have on the foetus?
allows more glucose to be provided for the foetus
47
what three effects does progesterone have throughout pregnancy?
development of decidual cells
decreases uterine contractility
prepares the body for lactation
48
describe levels of progesterone and oestrogen throughout pregnancy
rise throughout pregnancy
49
what three effects do oestrogen have during pregnancy?
enlargement of the uterus
breast development
relaxation of the pelvic ligaments
50
what happens to serum HCG levels in early singleton pregnancy?
double every 48 hours
51
what are HCG levels like in an ectopic pregnancy?
static or slow rising
52
what are HCG levels like in a failing pregnancy?
reducing
53
what side effects can HCG cause?
nausea and vomiting
54
when can HCG levels be higher than normal?
multiple pregnancies
| molar pregnancy
55
when do HCG levels start to fall?
from 12-14 weeks
56
what effect does placental CRH have on the mother?
increased ACTH resulting in increased aldosterone and cortisol
57
what effect can increased aldosterone have in a pregnant mother?
hypertension
58
what effect can increased cortisol have in a pregnant mother?
oedema
insulin resistance = gestational diabetes
59
what possible effect can HCG have on a pregnant mother?
hyperthyroidism
60
what possible effect can increased calcium demands in pregnancy have on the mother?
hyperparathyroidism
61
what happens to CO during pregnancy?
rises to 30-50% above normal
62
what causes the increase in CO during pregnancy?
the demands of the uteroplacental circulation
63
describe the CO throughout pregnancy?
begins to rise at 6 weeks
peaks around 24 weeks
decreases in the last 8 weeks
increases again during labour
64
what change in heart rate occurs during pregnancy?
increases up to 90/min to increase CO
65
what change in blood pressure occurs during pregnancy?
does during the second trimester
66
what causes the drop in BP in the second trimester?
the uteroplacental circulation expands and peripheral resistance decreases
67
how are the cardiovascular changes in pregnancy different when it is a multiple pregnancy?
CO increases more
BP drops more
68
is average pregnancy BP usually higher or lower than pre-pregnancy BP?
lower - usually by 15mmHg
69
what are BP levels like by the time the baby reaches term?
back to pre-pregnancy levels
70
what three haematological changes happen in the mother during pregnancy?
plasma volume increases
erythropoiesis increases
Hb is decreased by dilution
71
what happens to iron requirements during pregnancy and what can be done for this?
they increase significantly
iron supplements are often needed to prevent anaemia
72
what is the definition of anaemia in the first trimester?
Hb <110g/L
73
what is the definition of anaemia in the second and third trimesters?
<105g/L
74
what is the normal definition of anaemia?
Hb 120-160g/L
75
what causes respiratory changes during pregnancy in the mother?
progesterone increases
enlarging uterus interferes with lung function
76
what happens to the GFR and renal plasma flow in a pregnant mother?
increase
peaks at 16-24 weeks
77
what drives the increased re-absorption of ions and water in pregnancy?
placental steroids
| aldosterone
78
what effect does an upright position have on renal function in pregnancy?
decreases
79
what effect does an supine position have on renal function in pregnancy?
increases
80
what effect does a lateral position during sleep have on renal function in pregnancy?
increases LOTS
81
what is the reference range for ALT in a pregnant individual?
<30
82
what is the reference range for urea in a pregnant individual?
<3.5
83
what is the reference range for creatinine in a pregnant individual?
<50
84
what is the reference range for albumin in a pregnant individual?
20-40
85
what change occurs to maternal coagulation during pregnancy?
hyper coagulable state
86
what effects does the maternal hypercoagulable state have?
reduces risk of haemorrhage
| increases risk of VTE
87
what happens to factor II levels in pregnancy?
no change
88
what happens to factor VII, IX, X and XII levels in pregnancy?
increase
89
what happens to fibrinogen levels in pregnancy?
increases
90
what happens to factor XI levels in pregnancy?
reduce
91
what happens to protein S levels in pregnancy?
reduce
92
what happens to protein C levels in pregnancy?
no change
93
what happens to antithrombin levels in pregnancy?
no change
94
what happens to plasminogen levels in pregnancy?
increase
95
what happens to D-dimer levels in pregnancy?
increase
96
what happens to vWF levels in pregnancy?
increase
97
what weight change is normal during pregnancy?
average weight gain of around 11kg
can sometimes be up to 30kg
98
how many extra calories per day should be ingested by a pregnant mother?
200
99
what should the protein intake of a pregnant mother be?
extra intake of 30g/day
100
what are the two phases of pregnancy as defined by the mothers metabolism?
mothers anabolic phase in 1st - 20th week
21-40 week - catabolic phase
101
describe the metabolic needs of the mother and foetus during weeks 1-20
anabolic metabolism of the mother
quite small nutritional demands of the foetus
102
describe the metabolic needs of the mother and foetus during weeks 21-40
high metabolic demands of the foetus
results in accelerated starvation of the mother
103
what causes maternal insulin resistance?
HPL
cortisol
growth hormone
104
what effect does folic acid have in pregnancy?
reduces the risk of neural tube defects
105
how much folic acid should be taken throughout pregnancy?
400mcg per day in the first 12 weeks
ideally also for three months prior to conception
106
what dose of vitamin D supplements should be taken during pregnancy?
10mcgs a day
20mcgs if BMI > 30
107
what happens to the uterus towards the end of pregnancy?
it becomes progressively more excitable
108
what effect do progesterone and oestrogen have on uterine contractility?
```
progesterone = inhibits
oestrogen = promotes
```
109
what happens to progesterone levels towards term and when labour starts?
levels fall
110
what is parturition?
the birth of the baby
111
what are prostaglandins produced by during parturition?
placenta
myometrium
decidua
membranes
112
what do prostaglandins do during parturition?
help to ripen the cervix
| play a role in the onset of labour
113
what produces oxytocin?
the maternal posterior pituitary gland
114
what does oxytocin do during parturition?
increases contractions and excitability
115
what effect does increasing foetal size have on parturition?
stretches uterine muscles, increasing contractility
116
what substances are given to induce labour and how do they work?
prostaglandins - ripen the cervix
oxytocin when membranes have ruptured - increase contractions of the uterus
117
when do Braxton Hicks contractions increase?
towards the end of pregnancy
118
what are Braxton Hicks contractions?
sometimes called practice contractions
mild, irregular, don't require pain relief
119
when does cervical ripening occur?
just before the onset of labour
120
what is cervical ripening?
the softening of the cervix ti allow duration
121
what causes cervical ripening?
oestrogen
relax
prostaglandins
122
what hormone is released in response to cervical stretching in labour?
further oxytocin release
123
what causes intense abdominal muscle contractions in labour?
strong uterine contractions + pain cause neurogenic reflexes from the spinal cord, that have an impact on the abdominal muscles
124
what is the first stage of labour?
cervical dilation
125
how long does the first stage of labour take?
8-24 hours
126
what is the second stage of labour?
passage of the foetus through the birth canal
127
how long does the second stage of labour take?
from a few minutes to two hours
128
what is the third stage of labour?
expulsion of the placenta
129
what effect does oestrogen have on lactation?
stimulates growth of the ductile system
130
what effect does progesterone have on lactation?
development of the lobule alveolar system
131
overall, what effect do oestrogen and progesterone have on milk production?
INHIBITION
levels drop at birth
132
what hormone stimulates milk production in lactation?
prolactin
133
what hormone triggers the "milk let down" reflex?
oxytocin
