Physiology Flashcards
Stuff on pregnancy paturition periods and menopause
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What happens to the heart during pregnancy?
SV increases so CO increases by 40%
HR does not increase majorly
Systolic BP remains the same, diastolic may drop in 1st+2nd trimesters
Ankle oedema, supine hypotension and varicose veins are common
What happens to the lungs during pregnancy?
Increased metabolic rate - 20% - and increased O2 consumption:
Tidal vol increases, RR remains normal
Arterial pO2 increases, pCO2 decreases
Mild compensated respiratory alkalosis is normal in pregnancy
Pulmonary oedema is NOT normal
What happens to liver function during pregnancy?
ALP increases, albumin falls
Oestrogen + progesterone may slow or stop flow of bile - intrahepatic cholestasis of pregnancy- total serum bile acids increase
What happens to renal function during pregnancy?
In healthy kidneys:
50% increase in renal blood flow and GFR
Salt and water reabsorption increases due to elevated sex steroids
Pelvicaliceal system and ureters dilate - predisposing to upper UTI/pyelonephritis
Serum creatinine, rate and albumin fall (lower albumin means greater fluid retention)
Urine protein loss increases
What is the puerperium?
Time between delivery of placenta to 6wks post delivery
What endocrine changes occur in the puerperium?
Decrease in serum levels of placental hormones (human placental lactogen, hcg, oestrogen and progresterone)
Increase of prolactin - from anterior pituitary; responsible for milk production; inhibited by dopamine; high levels inhibit oestrogen
Oxytocin - responsible for ‘let down’ reflex where smooth muscle contracts around lobules, squeezing milk into ducts during suckling
What physiological changes occur in the puerperium?
Involution of the uterus and genital tract:
Muscle - ischaemia, autolysis and phagocytosis
Decidua (endometrium that has been under the influence of progesterone throughout pregnancy) – shed as lochia (discharge): Rubra (day 0-4, blood, cervical discharge, decidua etc)
Serosa (day 4-10, cervical mucuous, microorganisms, WBCs etc)
Alba (day 10-28, epithelial cells, cholesterol, fat, micororganisms, WBCs etc)
What happens to milk production?
At birth – presence of colostrum
Lactogenesis II – “onset of copious milk production” - stimulated by:
Prolactin – milk production
Oxytocin – Milk ejection reflex
Insulin and cortisol
Lactation suppression
7-10 days
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How does prolactin work?
Baby suckles - nipple sensations trigger PRL secretion by anterior pituitary gland - travels to breast in blood - stimulates lactocyte to produce milk
More is secreted at night, it suppresses ovulation, levels peak after the feed - stimulating more milk production for next feed
How does oxytocin work?
Baby suckles - triggers OXT release from posterior pituitary - blood stream to breasts - myo-epithelial cell contraction and expulsion of milk
Helped by sight/sound/smell of baby, conditioned over time, hindered by anxiety/pain/stress
What are the phases of labour and what happens in each?
Pre-labour:
Braxton Hicks contractions from c.wk 26
Discharge cervical mucous plug
First stage, latent phase:
Woman perceives regular uterine contractions
Cervical effacement = thinning and dilatation of cervix - >4cm by end of agent phase
First stage, active phase:
From 5c to full dilatation of c.10cm
Usually takes up to 10-12 hrs, average is 3-4hrs
Second stage, foetal expulsion:
Cervix fully dilated to when baby is born
Usually between 2-3hrs
Third stage, delivery of placenta:
Separates from uterus - uterus contracts and stops blood flow to placental vessels to stop haemorrhage
Average between 10-12mins
If cutting the umbilical cord is delayed by at least one minute or until it ceases to pulsate = reduced risk of neonatal jaundice + increased iron stores
What happens to blood during pregnancy?
Blood volume increases - red cells up 20% but plasma up 50% so Hb falls
Suppression of fibrinolytic activity, rise in fibrinogen and clotting factors - increased risk of thromboembolism
Platelets fall
WCC and ESR rise
WCC ratios of Th1:Th2 change - mean that some inflammatory conditions get better and some get worse
What happens biochemically in pregnancy?
Ca requirements increase - esp in 3rd trimester and whilst lactating - gut absorption increases but overall Serum Ca and phos fall
What endocrine changes happen in pregnancy?
Initially insulin sensitivity is high - lots of glucose absorbed and weight put on to prepare for growth of baby
Following this (possibly in the 2-3rd trimester), peripheral insulin sensitivity decreases (potentially to the point of resistance) due to levels of circulating oestrogen and cortisol
Human chorionic gonadotropin hormone (hCG):
Only produced during pregnancy - almost exclusively in the placenta
HCG hormone levels found in maternal blood and urine increase dramatically during the first trimester and may contribute to causing nausea and vomiting often associated with pregnancy
Human placental lactogen (hPL):
Produced by the placenta - helps in the process of providing nutrition for the fetus and plays a role in stimulating milk glands in the breasts in anticipation of breastfeeding
Oestrogen:
Responsible for the development of the female sexual characteristics
Normally formed in the ovaries, also produced by the placenta during pregnancy to help maintain a healthy pregnancy
Progesterone:
Produced by the ovaries and by the placenta during pregnancy
Progesterone stimulates the thickening of the uterine lining in anticipation of implantation of a fertilized egg
