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REPRODUCTION & GYNAECOLOGY > Physiology of Pregnancy and Lactation > Flashcards

Physiology of Pregnancy and Lactation Flashcards

1
Q

What name is given to the zygote immediately prior to becoming a blastocyst?

A

Morula

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2
Q

What are the two main parts of the blastocyst?

A

Inner cell mass - develops into foetus

Trophoblast - implants into uterine wall and becomes foetal portion of placenta

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3
Q

During what days of gestation does the embryo implant into the uterus?

A

5-8 days: blastocyst attaches to lining of uterus.

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4
Q

How do the trophoblastic cells penetrate the endometrium?

A
  • cords of trophoblastic cells penetrate the endometrium
  • These tunnel deeper and carve out a hole for the blastocyst
  • implantation finishes when the blastocyst is completely buried in the endometrium - DAY 12
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5
Q

Placenta is derived from both trophoblast and decidual tissue. TRUE/FALSE?

A

TRUE

=> both foetal and maternal tissue

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6
Q

Describe how the placenta develops

A
  • Trophoblasts differentiate into multinucleate cells
  • invade decidua and break down capillaries
    => form cavities filled with maternal blood
  • Embryo sends capillaries into trophoblast projections to form “placental villi”
  • Each villus contains foetal capillaries separated from maternal blood by a thin layer of tissue – no direct contact of foetal and maternal blood
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7
Q

What can be exchanged between foetal and maternal blood in the placenta?

A

respiratory gases
nutrients
metabolites
** largely down diffusion gradient **

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8
Q

When does the placenta become functional during pregnancy, and what other structure becomes functional at this point?

A

Placenta (and foetal heart) functional by 5th week of pregnancy

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9
Q

How is the early embryo delivered nutrients?

A
  • HCG signals corpus luteum to continue secreting progesterone
  • Progesterone stimulates maternal cells to concentrate glycogen, proteins and lipids for diffusion
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10
Q

Describe how circulation in the placenta works as a physiological arterio-venous shunt?

A
  • hair-like projections (villi) into uterine wall.
  • increases contact area between uterus and placenta
    => more nutrients and waste materials can be exchanged
  • Circulation within the intervillous space acts partly as an arteriovenous shunt.
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11
Q

Explain how the placenta plays the role of the foetal lungs?

A

O2 diffuses from maternal -> foetal circulation down concentration gradient

CO2 follows reverse conc gradient (due to partial pressure being elevated in foetal blood)

O2 saturated blood returns to fetus via umbilical vein
Maternal O2-poor blood, flows back into uterine veins.

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12
Q

Foetal haemoglobin is higher than that of adults. TRUE/FALSE?

A

TRUE

  • Higher Hb conc. in fetal blood
  • 50% more than adults
  • it also has a higher affinity for O2
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13
Q

How do water and electrolytes get into the placenta from the mother?

A
  • Water diffuses along osmotic gradient

- electrolytes follow water (iron and Ca2+ can only go from MOTHER -> CHILD)

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14
Q

How is glucose transported into the placenta and when is the most glucose required for the foetus during pregnancy?

A
  • simplified transport into placenta
  • glucose = main energy source for foetus
  • high glucose need in 3rd trimester
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15
Q

How do the majority of waste products exit the foetus back into the placenta?

A
  • diffusion based on concentration gradient
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16
Q

What prescription and non-prescription drugs can cross the placenta?

A
  • Teratogens e.g. valproate, carbamazepine, tetracycline

- Alcohol, nicotine, heroin, cocaine, caffeine

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17
Q

Why is HCG important in pregnancy?

A
  • promotes Corpus Luteum to remain and produce hormones (Progesterone and Oestrogen)
  • Has an effect on the testes of male fetus - development of sex organs
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18
Q

Why is Human Placental Lactogen (or Human Chorionic Somatomammotropin) needed in pregnancy?

A
  • produced from ~ week 5 of pregnancy
  • growth hormone-like effects: protein tissue formation.
  • decreases insulin sensitivity in mother => more glucose to foetus
  • breast development.
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19
Q

What is progesterone release responsible for during pregnancy?

A
  • development of decidual cells
  • decreases uterus contractility
  • preparation for lactation
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20
Q

What is the role of oestrogen in pregnancy?

A
  • enlargement of uterus
  • breast development
  • relaxation of ligments
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21
Q

What are estriol levels used to indicate in pregnancy?

A

estriol level - indicator of vitality of fetus

22
Q

What other hormonal changes can occur in pregnancy and what complications can these cause?

A
  • increased Aldosterone
    => salt and water retention
    => increased BP
  • Increased Cortisol
    =>oedema and insulin resistance
    => Gestational Diabetes
23
Q

The placenta and baby demand higher Ca2+ levels during pregnancy. What complication can this cause in the mother?

A

Hyperparathyroidism

24
Q

What cardiovascular adaptations may a pregnant woman experience?

A
  • Increased cardiac output (30 -50% more)
  • CO decreases in last 8 weeks
  • CO increases 30% more during labour
  • Heart rate increases (90bpm) => Increase CO.
  • Blood pressure drops during 2nd trimester (uteroplacental circ. expands and peripheral resistance decreases)
  • vasodilation occurs
25
Q

What haematological changes can be experienced by a mother in pregnancy?

A
  • plasma volume increases with CO (50%)
  • RBC erythropoesis increases
  • Hb is decreased by dilution (large PV)
  • Iron requirements increases (baby needs a lot of iron => mother may require supplements)
26
Q

What respiratory changes occur in a mother when she is pregnant?

A
  • progesterone signals to brain to lower CO2 levels

- O2 levels are increased (RR and Tidal vol increase) to meet demands of both mother and baby (20% more than normal)

27
Q

Explain how the urinary system of a pregnant mother is affected?

A
  • GFR and renal plasma flow increase
  • Increased re-absorption of ions and water (oedema)
  • Slight increase of urine formation
  • Postural changes affect renal functions
    - upright position DOWN
    - supine position UP
    - lateral position during sleep VERY UP
28
Q

What is pre-eclampsia?

A

pregnancy induced hypertension + proteinuria

29
Q

What signs other than increased blood pressure and proteinuria may be seen in pre-eclampsia?

A

Kidney function decline
=> salt and water retention
=> oedema formation (esp hands and face)
=> Renal blood flow and GFR decreases

30
Q

Pre-eclampsia is more common in what groups of women?

A
  • pre-existing hypertension
  • diabetes
  • autoimmune diseases (eg lupus)
  • renal disease
  • FHx of pre-eclampsia
  • obesity
  • multiple gestation (twins or multiple birth).
31
Q

What is the most significant risk factor for pre-eclampsia?

A

having had pre-eclampsia previously.

32
Q

What is Eclampsia?

A
  • EXTREME pre-eclampsia (lethal without Tx)

Symptoms:

  • vascular spasms
  • extreme hypertension
  • chronic seizures
  • coma
33
Q

How is eclampsia normally treated?

A
  • vasodilators

- cesarean section (best Tx is to get the baby OUT)

34
Q

How many kilograms does the average mother put on during pregnancy?

A

11kg (5kg foetus and 6kg mother)

35
Q

How are the average 11kg split up into different components of maternal weight gain during pregnancy?

A 
Foetus - 3.5kg
Extra-embryonic fluid/tissue - 2kg
Uterus - 1kg
Breasts - 1kg
Body Fluid - 2.5kg
Fat accumulation - 1kg
36
Q

what should a pregnant mother be eating more of during pregnancy in relation to metabolism and nutrition for the foetus?

A
  • 250 - 300 extra kcal/day for mother
  • Extra protein intake - 30g/day
  • At end of pregnancy - fetal glucose requirements higher => need to account for this
37
Q

What are the two different stages of metabolism that a mother experiences during pregnancy?

A

1st - 20th week - mother´s ANABOLIC phase:
- small nutritional demands of the foetus

21 - 40 week (esp. last trimester):

  • high metabolic demands of the fetus
  • accelerated starvation of the mother
38
Q

What usually happens during the mother’s anabolic metabolism phase of pregnancy?

A
  • normal/increased sensitivity to insulin
  • lower plasma glucose
  • lipogenesis, glycogen stores increases
  • growth of breasts/ uterus /weight gain
39
Q

What occurs during the mothers catabolic metabolism phase of pregnancy?

A
  • maternal insulin resistance
  • increased transport of nutrients through placental membrane
  • lipolysis
40
Q

What specific nutritional needs are important in pregnancy?

A
  • Folic acid (folate) - reduces risk of neural tube defects
  • Vitamin D supplements
  • High protein diet, higher energy uptake
  • Iron supplements may be required
  • B - vitamins - erythropoesis
41
Q

Why should folic acid ideally be taken BEFORE pregnancy begins?

A
  • it is taken to prevent neural tube defects

BUT often neural tube has formed BEFORE patient knows they are pregnant

42
Q

Describe how the uterus becomes more “excitable” towards the end of pregnancy?

A
  • Oestrogen:Progesterone ratio INCREASES
    => oestrogen increases contractility and oxytocin receptors on uterus
  • Oxytocin (posterior pituitary)
    => increases contractions and excitability
    => stimulates placenta to make prostaglandins
  • Foetal hormones: oxytocin, adrenal gland, prostaglandin (control timing of labour)
  • Mechanical stretch of uterine muscles increases contractility
  • Stretch of the cervix also stimulate uterine contractions
43
Q

What are Braxton Hicks contractions?

A

Small contractions that do NOT indicate labour

- these increase toward the end of pregnancy

44
Q

Describe how stretching of the cervix causes positive feedback?

A

stretch of the cervix by fetal head
=> increases contractility
=> causes further oxytocin release

45
Q

How may a woman engage abdominal muscle contractions during labour?

A
  • Strong uterine contraction / pain from birth canal cause neurogenic reflexes from spinal cord

=> Induce intense abdominal muscle contractions

46
Q

What are the 3 stages of Labour?

A

1st stage: cervical dilation (8-24 hours).
2nd stage: passage through birth canal (few min to 120 mins).
3rd stage: expulsion of placenta.

47
Q

How are the means to lactate developed in the mother during pregnancy?

A

Oestrogen = stimulates growth of ductile system
Progesterone: development of lobule-alveolar system
Prolactin stimulates milk production (steady rise in levels wk 5 – birth).

48
Q

Why can milk only normally be produced AFTER women give birth?

A

Oestrogen and Progesterone inhibit milk production

=> At birth sudden drop in both

49
Q

How soon after birth does prolactin stimulate milk production and what are the contents of the first milk produced?

A
  • 1-7 days after birth, prolactin induces high milk production.
  • Stimulates colostrum (low volume, no fat)
50
Q

What does the baby do to allow milk ejection from the mother’s breast?

A
  • suckling on mechanoreceptors in nipple
  • this sends signal to higher brain centres to allow production of oxytocin (for smooth muscle contraction) and prolactin (for milk production)
51
Q

Why may a post-partum haemorrhage occur after the delivery of the placenta?

A

If the womb doesn’t contract down after placenta is delivered (to condense surface area and vasculature)
then haemorrhage is likely to occur

REPRODUCTION & GYNAECOLOGY (58 decks)

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