Physiology of Pregnancy and Lactation Flashcards
At Day 1: Fertilization occurs in the ______ of the Fallopian Tube.
At Day 1: Fertilization occurs in the ampulle of the Fallopian Tube.
3-5 days: Transport of ______ into the _____
3-5 days: Transport of blastocyst into the uterus
5-8 days: _____ attaches to _____ of uterus.
5-8 days: blastocyst attaches to lining of uterus.
Blastocyst: - ____ cells develop into embryo - Outer cells burrow into uterine wall and become ______
Blastocyst: - inner cells develop into embryo - Outer cells burrow into uterine wall and become placenta
What happens when the blastocyst adheres to the endometrial lining?
cords of trophoblastic cells begin to penetrate the endometrium
What do advancing cords of trophoblastic cells do?
tunnel deeper into endometrium, carving out a hole for the blastocyst. The boundaries between cells in the advancing trophoblastic tissue disintegrate
When implantation is finished the blastocyst is _______ ______ in the endometrium - by day __
When implantation is finished the blastocyst is completely buried in the endometrium - by day 12
What is the placenta derived from?
Trophoblast and decidual tissue
What do trophoblastic cells do?
Trophoblastic cells (chorion) differentiate into multinucleate cells (syncitiotrophoblasts) which invade decidua and break down capillaries to form cavities filled with maternal blood
How do placental villi form?
Developing embryo sends capillaries into the syncitiotrophoblast to form placental villi
What does each placental villus contain?
contains fetal capillaries
Is there direct contact between foetal and maternal blood?
No - fetal capillaries separated from maternal blood by a thin layer of tissue
When is the placenta and foetal heart functional?
by 5th week of pregancy
Describe early nutrition of the embryo
- invasion of trophoblastic cells into the decidua
- Human chorionic gonadotropin (HCG) signals the corpus luteum to continue secreting progesterone
- Progesterone stimulates decidual cells to concentrate glycogen, proteins and lipids
How does the placenta increase contact area between uterus and placenta?
As it develops it extends villi into uterine wall so that more nutrients and waste products can be exchanged
Circulation within the intervillous space acts partly as an ________ _____.
Circulation within the intervillous space acts partly as an arteriovenous shunt.
What role does the placenta play?
The role of the foetal lungs
What is the respiratory function of the placenta?
Makes supply of oxygen and removal or carbon dioxide
Oxygen diffuses from the maternal into the foetal circulation (PO2 ____ > PO2 ____)
Oxygen diffuses from the maternal into the foetal circulation (PO2 maternal > PO2 foetal)
Carbon dioxide (partial pressure is elevated in _____ blood) follows a _____ gradient.
Carbon dioxide (partial pressure is elevated in foetal blood) follows a reversed gradient.
Fetal, oxygen-saturated blood, returns to the fetus via the ______ vein, while maternal, oxygen-poor blood, flows back into the _____ veins.
Fetal, oxygen-saturated blood, returns to the fetus via the umbilical vein, while maternal, oxygen-poor blood, flows back into the uterine veins.
What three factors facilitate oxygen transport to the foetus?
- Foetal Hb (increased ability to carry O2)
- Higher Hb concentration in foetal blood (50% more than in adults)
- Bohr effect (foetal Hb can carry more oxygen in low pCO2 than in high pCO2)
What classic transport mechanisms do placental exchange processes occur via?
- Passivetransport (without energy consumption)
- Simple diffusion
- Osmosis
- Simplified transport
- Active transport
Water diffuses into placenta along its ______ gradient. Exchange increases during pregnancy up to the __th week (___l/day)
Water diffuses into placenta along its osmotic gradient. Exchange increases during pregnancy up to the 35th week (3.5l/day)
Electrolytes follow ___ (____ and ____) only go from mother to child.
Electrolytes follow H2O (iron and Ca2+) only go from mother to child.
Glucose, (foetus’ main source of energy), passes the placenta via ______ transport (high glucose need in ___ trimester).
Glucose, (foetus’ main source of energy), passes the placenta via simplified transport (high glucose need in 3rd trimester).
There is free diffusion of _____ _____ across the placenta
There is free diffusion of fatty acids across the placenta
What is diffusion of waste products across the placenta based upon?
The concentration gradient
What % of all congenital malformations are due to drugs?
3%
What does HCG prevent?
Prevents involution of corpus luteum by stimulating progesterone and oestrogen.
What does HCG contribute to the development of?
Development of foetal sex organs
What is human placental lactogen (human chorionic somatomammotropin)?
Hormone produced from week 5 of pregnancy
What does human placental lactogen (human chorionic somatomammotropin) do?
Growth hormone life efffects- protein tissue formation
Decreases insulin sensitivity in mother (more glucose for the foetus)
Involved in breast development
What does the rise in progesterone cause?
- development of decidual cells
- decreases uterus contractility
- preparation for lactation
What does the rise in oestrogens cause?
- enlargement of uterus
- breast development
- relaxation of ligaments
The serum level of HCG doubles every __ hours in a singleton early pregnancy
The serum level of HCG doubles every 48 hours in a singleton early pregnancy
What can changes in levels of HCG be used to diagnose?
- ectopic pregnancy (static or slow rising)
- failing pregnancy (falling)
- ongoing viable pregnancy (doubling or >60% rise)
What are the side effects of HCG rising?
Nausea and vomitting
What can cause very high levels of HCG?
Multiple pregnancy
Molar pregnancy
When do HCG levels begin to fall?
12-14 weeks
Placenta produces CRH (corticotrophin releasing hormone) which is turned into ____ by mother.
This makes ________ and ______.
_________- increases BP
_______- Oedema & insulin resistance = _________ _______
Placenta produces CRH (corticotrophin releasing hormone) which is turned into ACTH by mother.
This makes aldosterone and cortisol.
Aldosterone- increases BP
Cortisol- Oedema & insulin resistance = gestational diabetes
Placenta produces HCG (HC thyrotropin) which causes __________ in the mother.
Placenta produces HCG (HC thyrotropin) which causes hyperthyroidism in the mother.
The increased Ca2+ demands of the placenta cause hyperparathyoidism in the mother.
The increased ____+ ________ of the placenta cause hyperparathyoidism in the mother.
Increase in Cardiac Output (CO) during pregnancy is due to demands of the __________ ________.
Increase in Cardiac Output (CO) during pregnancy is due to demands of the uteroplacental circulation.
CO is __-__% above normal (beginning at 6 weeks gestation and peaking at around __ weeks)
CO is 30-50% above normal (beginning at 6 weeks gestation and peaking at around 24 weeks)
What can increased CO present as?
Physiological;
- ECG changes
- functional murmurs
- heart sounds
When does CO decrease?
In last 8 weeks
In the last 8 weeks CO becomes sensitive to what?
To body position- compresses vena cava
CO increases __% more during labour.
CO increases 30% more during labour.
Heart rate (HR) increases up to __ beats/min to increase CO.
Heart rate (HR) increases up to 90 beats/min to increase CO.
When does BP drop and why?
During 2nd trimester (uteroplacental circulation expands & peripheral resistance decreases)
With multiple pregnancy __ increases more and __ drops more
With multiple pregnancy CO increases more and BP drops more
What are the haematologic changes of pregnancy?
- plasma volume increases proportionally with CO (50%)
- Erythropoeisis (RBC) increases 25%
- Hb is decreased by dilution (increasing blood viscosity)
- iron requirements increases significantly (6-7mg/day in 2nd half of pregnancy)
Why does lung function change in pregnancy?
Partly due to progesterone increases and partly because the enlarging uterus interferes with lung function.
Describe the respiratory changes in pregnancy
Progesterone signals the brain to lower CO2 levels
O2 consumption increases to meet metabolic need of foetus, placenta and mother (20% above normal)
Growing uterus
How are CO2 levels reduced in pregnancy?
- RR increases
- tidal and minute volume increases (50%)
- pCO2 decreases slightly
- vital capacity and PO2 don’t change
Describe the urinary system changes in pregnancy?
- GFR and RPF increases up to 30-50% peaking at 16-24 weeks
- increased re-absorption of ions and water
- placental steroids
- aldosterone
- slight increase of urine formation
Postural changes affect renal function
- upright position (Decreased)
- supine posiiton (increased)
- lateral position during sleep (marked increase)
What is pre-eclampsia?
Pregnancy induced hypertension + proteinuria
How does kidney function deterioration present?
Oedema formation (especially hands and face)
Who is more likely to get pre-eclampsia?
Women with;
- pre-existing hypertension
- diabetes
- autoimmune disease (lupus)
- renal disease
- FHx of pre-eclampsia
- obesity
- multiple pregnancy
What is the single most significant risk factor for pre-eclampsia?
Previous pre-eclampsia
What causes pre-eclampsia?
Unsure
- extensive secretion of placental hormones?
- immune response to foetus?
- insufficient blood supply to placenta- ischaemia?
What is eclampsia?
Extreme pre-eclampsia (fatal without treatment)
How does eclampsia present?
Vascular spasms
Extreme hypertension
Chronic seizures
Coma
What is the treatment for eclampsia?
Vasodilators and caesarean section
What is the average weight gain in pregnancy?
11kg
5kg- foetus
6kg - mother
how many extra calories/protein should be ingested per day by mother?
200 extra kcal/day
30g/day protein
At end of pregnancy foetal glucose need is 5mg/kg/min and mothers is 2.5mg/kg/min
What are the two phases of pregnancy regarding nutrition?
1st phase- mothers anabolic phase 1st-20th week
- anabolic metabolism of mother
- quite small nutritional demands of the conceptus
2nd phase- 21-40th week
- high metaboic demands of foetus
- accelerated starvation of mother
Describe mothers anabolic phase?
- normal or increased sensitivity to insulin
- lower plasmatic glucose level
- lipogenesis, glucogen stores increase
- growth of breast, uterus, weight gain
Describe mothers catabolic phase?
- Maternal insulin resistance- caused by HPL, cortisol and GH
- increased transport of nutrients thorugh placental membrane
- lipolysis
What are the special nutritional needs in pregnancy?
- folic acid (folate)- reduces risks of neural tube defects
- vitamin D supplements
- higher protein diet, higher energy uptake
- iron supplementation
- B vitamins- erythropoeisis
What alters the excitability of uterus?
- Estrogen:progesterone ratio alters increasing excitability
- Progesterone inhibits contractility while oestrogen increases contractility*
- oxytocin from maternal PP glandl increases contractions and excitability
What do foetal hormones do during parturition?
Oxytoxin, adrenal gland, prostaglandin= control timing of labour
Mechanical stretch of _______ _______ increases contractility
Stretch of the ______ also stimulates uterine contractions
Mechanical stretch of uterine muscles increases contractility
Stretch of the cervix also stimulates uterine contractions
Describe the onset of labour
- Braxton Hicks contractions
- increase toward the end of pregnancy
- Positive feedback
- stretch of the cervix by fetal head increases contractility
- Cervical stretching also cause further oxytocin release
- Strong uterine contraction and pain from the birth canal cause neurogenic reflexes from spinal cord that induce intense abdominal muscle contractions
What are the three stages of labour?
1st stage: cervical dilation (8-24 hours)
2nd stage: passage through birth canal (few min to 120 mins)
3rd stage: expulsion of placenta
What does oestrogen stimulate regarding lactation?
Growth of ductile system
What does progesterone stimulate regarding lactation?
Development of lobule-alveolar system
What do E and P inhibit?
Milk production
What stimulates milk production
Prolactin- steady rise from week 5-birth
_-_ days after birth, prolactin induces high milk production.
Stimulates colostrum (low _____, no ___)
1-7 days after birth, prolactin induces high milk production.
Stimulates colostrum (low volume, no fat)
What causes milk let-down reflex
Sucking stimulus and oxytoxin
