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human development > physiology of pregnancy > Flashcards

physiology of pregnancy Flashcards

1
Q

why do physiological adaptations need to occur?

A

to;
o Support the developing fetus
o Prepare the mother for labour

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2
Q

what cardiovascular changes occur during pregnancy?

A 
increased plasma volume
increase in erythrocyte production
increased cardiac output
fall in blood pressure
hypercoagulable state
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3
Q

how does blood volume change over the course of pregnancy?

A
  • Blood volume starts to increase during 1st trimester
  • Expands rapidly during 2nd trimester
  • Rises at a lower rate during 3rd trimester
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4
Q

how much can plasma volume increase overall during pregnancy?

A

45%

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5
Q

what follows an increase in plasma volume during pregnancy?

A

increase in total erythrocyte volume

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6
Q

how does dilution anaemia occur?

A

• Increase in RBC is smaller relative to that of plasma volume

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7
Q

how does Hb concentration change during pregnancy?

A

falls from around 150g/l pre-pregnancy to 120g/l during the third trimester

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8
Q

what stimulates erythropoiesis?

A

an increase in renal erythropoietin production

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9
Q

how does cardiac output change over the course of pregnancy?

A
  • Cardiac output increases by 35-40% in the first trimester

* CO increases slightly during 2nd and 3rd trimesters, approx. 50% at term

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10
Q

what causes increased CO?

A

increased HR and SV

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11
Q

why does stroke volume increase during pregnancy?

A

o Increase in ventricular wall muscle mass
o Heart is physiologically dilated
o Myocardial contractility is increased

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12
Q

how does the distribution of CO change during pregnancy?

A

o Mainly increase blood flow to uterus (2%  17%)

oSlight increase to breast

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13
Q

how does MABP change during pregnancy?

A

MABP stays the same/falls slightly

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14
Q

when does BP reach its lowest point during pregnancy?

A

between 17-24 weeks of pregnancy

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15
Q

how is MAP calculated?

A

CO x TPR

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16
Q

how does TPR change during pregnancy and why?

A

decreased TPR bc CO is increased to maintain BP around the same state

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17
Q

how does peripheral vascular resistance change during pregnancy?

A

falls by 50% during early pregnancy

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18
Q

what causes peripheral vasodilation?

A

o Progesterone – key role in relaxing smooth muscle.
o Oestrogen, nitric oxide, relaxin and calcitonin gene-related peptide are also implicated in causing vasodilation
o Other influences include placenta, an additional organ – contributes an extra blood vessel circuit

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19
Q

what is the effect of an enlarged uterus on blood flow?

A

• Enlarged uterus (around 3rd trimester) can cause compression of vena cava –> impedes venous return to heart –> reduction in CO and BP (contributes to maternal hypotension)

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20
Q

how should pregnant women be positioned for BP measurements?

A

on the side - not supine

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21
Q

what is pre-eclampsia characterised by?

A

characterised by high blood pressure with proteinuria and oedema

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22
Q

what is haemostasis?

A

the process of coagulation depending on enzymatic activity, which culminates in the form of a stable, vascular plug

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23
Q

what is fibrinolysis?

A

clot dissolution that occurs during the healing phase

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24
Q

what is a hypercoagulable state?

A

– increased tendency towards blood clotting

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25
Q

why is it important for pregnancy to induce a hypercoagulable state?

A

important to maintain placental function during pregnancy and as prep to prevent excessive bleeding during delivery

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26
Q

which clotting factors increase during pregnancy?

A

all clotting factors gradually increase - EXCEPT XI and Tissue factor (TF)

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27
Q

do coagulation inhibitors increase or decrease during pregnancy?

A

decrease

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28
Q

what haemostatic changes occur in pregnancy?

A

o Increased platelet production
o Decreased platelet count (reflects increased activity and consumption)
o Inhibition of fibrinolysis activity

29
Q

what is thrombosis/thromboembolism?

A

localised blood clot forming where it shouldnt

30
Q

who is affected by thrombosis/thromboembolism?

A

Affects 1/1000 women under the age of 35

31
Q

what physiological changes to the respiratory system occur during pregnancy?

A

increased O2 consumption
increased alveolar ventilation
increased minute ventilation
large increase in tidal volume

32
Q

why is there increased O2 consumption during pregnancy?

A

maintains the additional metabolic requirements of pregnancy

33
Q

what is alveolar ventilation?

A

amount of air that reaches the alveoli and is available for gas exchange with the blood

34
Q

what is minute ventilation?

A

volume of gas inhaled/exhaled from lungs/min

35
Q

why is minute ventilation increased?

A

large increase in tidal volume

respiratory rate slightly increased

36
Q

what are the mechanisms of increase in ventilation?

A
  • Progesterone-mediated hypersensitivity to CO2

* Progesterone stimulates the respiratory centre directly to increase sensitivity to carbon dioxide

37
Q

what changes in lung volume occur during pregnancy?

A
  • Decrease in total lung capacity
  • Increased tidal volume
  • Decrease in expiratory reserve volume
  • Decrease in residual volume
  • Expanding uterus
38
Q

what changes does increased ventilation cause to an ABG?

A

fall in PaCO2 and slight rise in PaO2

39
Q

what acid-base changes does hyperventilation lead to? how is this compensated?

A
  • Leads to development of chronic respiratory alkalosis

* Renal compensation (HCO3- loss, H+ retention)

40
Q

what changes occur to the kidneys during pregnancy?

A
  • increase in length
  • dilation of the renal calyces, pelvis and ureter mainly due to the action of progesterone to relax smooth muscle
  • increased renal plasma flow
  • increased glomerular filtration rate
  • Increase in urea, creatinine, urate clearance and excretion of bicarbonate
41
Q

what is glycosuria? why does it occur?

A

decrease in reabsorption of glucose

Due to increase in filtered load of glucose which is greater than the ability of the proximal tubule to reabsorb glucose

42
Q

how do prorenin, renin and angiotensinogen change during pregnancy?

A
  • Prorenin: peaks 8-12 weeks of gestation
  • Renin: rises around 20 weeks of gestation
  • Significant increase in Angiotensinogen
43
Q

how does oestrogen affect renin secretion?

A

increases renin secretion from granular cells

44
Q

how does oestrogen affect angiotensinogen?

A

upregulate angiotensinogen production in the liver

45
Q

what does increased activity of RAAS in early pregnancy lead to?

A

leads to water retention + decrease in plasma osmolarity

46
Q

what does increased aldosterone secretion during pregnancy lead to?

A

reabsorption of salt + water

47
Q

name markers of liver function

A

alanine aminotransferase
aspartate transaminase
lactate dehydrogenase
gamma-glutamyl transferase

48
Q

what are clinical signs of liver disease?

A

spider naevi and palmar erythema may occur

49
Q

what action does pregnancy have on GI function?

A
  • heartburn/reflux common
  • Progesterone-mediated reduction in lower oesophageal sphincter tone
  • • Predisposition to regurgitation and aspiration during anaesthesia
    • Small and large bowel – decrease in tone and motility
    • 60% increase in water absorption
    • Constipation
    • Haemorrhoid formation
50
Q

why is heartburn/reflux common in pregnancy?

A

partly bc of increased intra-abdominal pressure (aggravated in supine position)

51
Q

how is pancreatic function affected by pregnancy?

A
  • Pancreatic islets of Langerhans – hyperplasia of insulin producing β-cells: Increased insulin production
  • Early pregnancy tissues show an increased sensitivity to insulin and plasma glucose may fall
  • Late pregnancy insulin response blunted by placental hormones and plasma glucose may rise.
  • Increased placental glucose uptake
52
Q

what is parturition?

A

labour or the act of giving birth

53
Q

what are the 3 stages of labour?

A

o Dilation of cervix/uterine contractions
o Fetal expulsion
o Placental expulsion

54
Q

what changes occur to cardiac output during labour?

A

o Increases bc “autotransfusion” from contracting uterus.
o Further increase in blood may be autotransfused as placenta delivered.
o Pain/anxiety and stimulation of sympathetic nervous system also increases heart rate and possibly blood pressure.

55
Q

what postpartum changes are there to the cardiovascular system?

A

o Blood volume decreases by 20% in 72hrs postpartum
o Heart rate and CO decreases to baseline in 2 weeks
o Proteins and lipids decrease to baseline in 2-3 weeks

56
Q

what postpartum changes are there to the urinary system?

A

o Functional change – prompt return to baseline with decreased blood volume
o Structural change - Dilatation of bladder, ureters and renal pelvis – persist for  3 months

57
Q

when does the mammary gland start developing?

A

start of puberty

58
Q

what hormones regulate the development of the non-pregnant adult mammary gland?

A

progesterone and oestrogen

59
Q

how do mammary glands develop during puberty?

A

• Lactiferous ducts and alveoli (lobes) develop but the breast is not capable of large-scale mile production (lactogenesis)

60
Q

how does the mammary gland develop during pregnancy?

A
  • Lobular ductal-alveolar system undergoes hypertrophy.
  • Proliferation of ducts.
  • Alveoli mature.
  • Deposition of adipose tissue between lobules of the gland
61
Q

what hormones regulate development of the mammary gland during pregnancy?

A
  • Controlled by placental steroids: estradiol and progesterone as well as placental peptide hormone (hPL).
  • Pituitary growth hormone and prolactin may also have a role.
62
Q

when is the breast fully developed for milk production?

A

middle of pregnancy

63
Q

what is prolactin?

A

primary lactogenic hormone (initiates milk production)

64
Q

what inhibits secretory activity of mammalian tissue?

A

steroid secretion (placental steroids: oestrogen and progesterone)

65
Q

what triggers lactogenesis?

A

triggered post-delivery by fall in steroid secretion (placental steroids: oestrogen and progesterone).

66
Q

what hormone is needed for the milk ejection reflex?

A

oxytocin

67
Q

what stimulates oxytocin release?

A

in response to suckling

68
Q

how does the milk ejection reflex occur?

A

oxytocin secreted

Contraction of myoepithelial cells – release milk from alveoli and small ducts into large ducts and sinuses

human development (20 decks)

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