Physiology Flashcards
what does the zygote divide into?
blastocyst which is transported to the uterus
what happens day 3-5 after fertilisation?
blastocyst is transported to the uterus
what happens days 5-8 after fertilisation?
blastocyst attaches to the lining of the uterus
how does the blastocyst attach to the lining of the uterus?
cords of trophoblastic cells penetrate the endometrium
what is the placenta derived from?
trophoblast and decidual tissue
role of trophoblast cells
invade decidua and break down capillaries to form cavities filled with maternal blood
what separates maternal and foetal blood?
thin membrane
AV shunt?
what week are the placenta and heart functional by?
week 5
role of hCG
prevents degeneration of the corpus luteum
role of human placental lactogen (HCS)
produced from week 5
protein formation
decreases insulin sensitivity in mother so more for foetus
role of progesterone in pregnancy
develops decidual cells
decreases uterine contraction
prepares lactation
role of oestrogen in pregnancy
enlarges uterus
breast development
relaxation of ligaments
what conditions is HCG useful in the diagnosis of?
ectopic= static or slow rising
failing pregnancy= falling
viable pregnancy= double or >60% rise
side effects of HCG
N&V
what conditions lead to more hCG?
multiple pregnancy
molar pregnancy
what week do hCG levels fall?
12-14 weeks
what happens when the placenta produces CRH?
increases ACTH in mother increasing aldosterone and cortisol
risks hypertension, oedema, GDM
cardiovascular changes in pregnancy?
increased CO
increased HR
BP drops in semester 2
why does BP drop in semester 2?
uteroplacental circulation expands
PVR decreases
haematological changes in pregnancy
plasma volume increased
EPO increases (increased RBC)
Hb decreases
why does Hb decrease?
dilution
iron requirements increase
respiratory changes in pregnancy
progesterone signals to lower CO2 levels (increase pH
O2 consumption increases
increased RR and TV
urinary changes in pregnancy
GFR and RPF increased
increased re-absorption of ions and water
increased UO
postural changes affect renal function
postural changes that affect renal function
upright decreases
supine increases
circulatory changes in pregnancy
hypercoagulable state
VTE risk
metabolic changes in pregnancy
weight gain
21-40 weeks catabolic phase
specific nutritional needs in pregnancy
folic acid vitamin D protein energy iron B-vitamins (erythropoiesis)
what hormones induce labour?
oestrogen inducing oxytocin receptors
what do oestrogen and oxytocin do in labour?
stimulates uterus contraction and make prostaglandins
three stages of labour
- cervical dilatation (8-24 hours)
- passage of foetus through the birth canal (minutes-120 minutes)
- expulsion of placenta and membranes (<10 minutes)
active cervical dilatation
4-10cm
when is stage 2 of labour considered prolonged?
3 hours
2 hours in multiparous women
when is surgery needed for stage 3 of labour?
> 1 hour
active management of stage 3?
syntometerine or oxytocin
what is Bishops score used for?
determine whether it is safe to induce labour
what is liquor?
fluid that surrounds the foetus
true labour contractions (compared to Braxton Hicks)
under oxytocin
evenly spaced, getting shorter
length of contraction increases
thinning of cervix
three reasons why labour may not be progressing?
- power
- passage
- passenger
pacemaker of uterus smooth muscle contraction
fundus the tubal ostia
ideal passage pelvic shape
gynaecoid
what can failure to progress risk?
obstructed labour
risks in obstructed labour
sepsis
AKI
fistula formation
foetal asphyxia
signs of obstruction
moulding caput (oedema) anuria haematuria vulval oedema
what does a partogram assess?
assess progress of labour
7 cardinal movements of baby in pelvis
- Engagement
- Descent
- Flexion
- Internal rotation
- Crowning and extension
- Restitution and external rotation
- Expulsion of anterior shoulder first
what is crowning?
appearance of the foetal head at the introitus
actions taken once baby born?
delayed clamping
skin-to-skin contact
analgesics options in labour
massage water immersion IM opiates paracetamol/ co-codamol TENS entonox (oxygen + NO, gas and air) diamorphine epidural (levobupivacaine +/- opiate) spinal
which analgesic can inhibit progress in stage 2?
epidural
complications with anaesthetics used in labour
hypotension
dural puncture
atonic bladder
intrapartum foetal assessment
- foetal heart + maternal pulse
- CTG
- amniotic fluid
what does a CTG show?
contraction frequency
decelerations
accelerations
variability
DRCBRAVADO= determine risk contractions baseline rate variability acceleration decelerations overall impression
oestrogen in breast feeding
grows ductile system
progesterone in breast feeding
grows lobule-alveolar system
role of prolactin in breast feeding
stimulates milk production
role of oxytocin in breast feeding
let-out reflex
what is the puerperium?
6 week period following birth with tissues returning to non-pregnant state
how long does lochia last?
discharge containing blood, mucus and endometrial casting lasting around 10-14 days
how long does it take BP to return to normal
6 weeks
placental functions
foetal homeostasis gas exchange nutrition/waste transport acid-base balance hormone production transport of IgG
three shunts in the foetal circulation
ductus venosus
foramen ovale
ductus arteriosus
fates of the shunts
- FO closes (but can persist as PFO)
- Ductus arteriosus becomes ligamentum arteriosus (but can persist as PDA)
- Ductus venosus becomes ligamentum teres
preparations for birth in the 3rd trimester
surfactant production accumulation of glycogen brown fat subcutaneous fat swallowing amniotic fluid
adaptions in first few hours of life
thermoregulation
no shivering > breakdown brown fat
ketones as brain fuel
when is there a risk of hypothermia in babies?
preterm with low brown fat and subcutaneous stores, large SA
when is there a risk of hypoglycaemia in babies?
increased demand (unwell, hypothermic)
premature
small for dates
maternal diabetes and hyperinsulinaemia
why does physiological jaundice happen?
breakdown of foetal Hb with immature conjugating pathways causing circulating unconjugated bilirubin
