Physiology of Pregnancy and Lactation Flashcards
What does the fertilised ovum do?
Progressively divides and differentiates into a blastocyst
Where does the fertilised ovum move to?
Site of fertilisation in the upper oviduct (ampulla to the site of implantation in the uterus
What sweeps the ovum into the oviduct?
Fimbrae
What happens at day 1?
Fertilisation occurs in the ampulla of the fallopian tube
What happens at days 3-5?
Transport of blastocyst into the uterus
What happens at days 5-8?
Blastocyst attaches to lining of uterus
What happens to the blastocyst?
Inner cells develop into embryo
Outer cells burrow into uterine wall and become placenta
What does the placenta do?
Produce several hormones to maintain pregnancy
What happens when the blastocyst adheres to the endometrial lining?
Cords of trophoblastic cells begin to penetrate the endometrium
What happens by day 12?
Implantation is completed and the blastocyte is buried in the uterine lining
What is the placenta derived from?
Trophoblast and decidual tissue
What happens to trophoblastic cells (Chorion)?
Differentiates into multinucleated cells (Syncytiotrophoblasts) which invade decidua and break down capillaries to form cavities filled with maternal blood
How are placental villi formed?
Embryo sends capillaries into the syncytiotrophoblast projections
What does each villus contain?
Foetal capillaries separated by maternal blood by a thin layer of tissue
Is there any direct contact between foetal and maternal blood?
No
What is functional by week 5 of the pregnancy>
Placenta
Foetal heart
What helps with embryo nutrition?
Invasion of trophoblastic cells into the decidua
What does Human chorionic gonadotrophin (HCG) do?
Signals the corpus luteum to continue secreting progesterone - stimulating decidual cells to concentrate glycogen, proteins and lipids
What acts as an arteriovenous shunt?
Circulation within the intervillous space
What does the placenta play the role of?
The foetal lungs
What 3 factors facilitate the oxygen supply to the foetus?
Fetal Hb (increased ability to carry O2) Higher Hb (concentration in fetal blood 50% more than in adults) Bohr effects (fetal Hb can carry more O2 in low pCO2 than in higher pCO2)
Water diffusion increases until which week?
35th (3.5l/day)
When is a higher concentration of glucose required?
3rd trimester
Describe Human Chorionic Somatomammotrophin (HCS)
Produced from week 5
Growth hormone effect
Decreases insulin sensitivity in mother
Involved in breast development
What does changes in progesterone cause?
Development of decidual cells
Decreased uterus contractibility
Preparation for lactation
What does changes in estrogens cause?
Enlargement of uterus
Breast development
Relaxation of ligaments
Estriol level - indicator of vitality of foetus
Cardiac output increases by what until when?
Up by 30-50% until last 8 weeks
How high is the heart rate to accomodate the increased CO?
90/min
When does the BP drop?
2nd trimester
What happens to the CO and BP if the mother is carrying twins?
CO increases more
BP drops more
What happens to the plasma volume?
Increases proportionally with CO (50%)
What happens to Hb?
Decreases by dilution (Decreases blood viscosity)
What respiratory changes happen to lower CO2 levels?
Respiratory rate increases
Tidal volume and minute volume increase (50%)
pCO2 decreases slightly
Vital capacity and pO2 don’t change
What happens to the Glomerular Filtration Rate and Renal Plasma Flow?
Increases up to 30-50%, peaking at 16-24 weeks
What are features of pre-aclampsia?
Oedema
Hypertension
Proteinuria
GFR and renal plasma flow decreases
What happens in eclampsia?
Vascular spasms Severe hypertension Chronic seizures Coma Death
What is the treatment of eclampsia?
Vasodilators
Cesarean section
How much extra kcal/day should be consumed by the mother?
250-300
How much extra protein should the mother consume?
30g/day
Describe the 1st metabolic phase of pregnancy?
1st-20th week
Mother’s anabolic phase
Anabolic metabolism of the mother
Quite small nutritional demands of the conceptus
Describe the 2nd metabolic phase of pregnancy?
21-40th week (esp. last trimester)
high metabolic demands of fetus
Accelerated starvation of mother
What happens in the mothers anabolic phase?
Normal or increased sensitivity to insulin
Lower plasmatic glucose level
Lipogenesis, glycogen stores increase
Growth of breasts, uterus, weight gain
What happens in the catabolic phase?
Maternal insulin resistance
Increased transport of nutrients through placental membrane
lipolysis
What causes insulin resistance?
HCS
Cortisol
Growth hormone
What is the purpose of taking folic acid (folate) during pregnancy?
Reduces risk of neural tube defects
What is the purpose of taking vitamin K and when should it be taken?
Prevention of intercranial bleeding during labour
Before parturition
What is erythropoesis?
making red blood cells
What does cervical stretching cause?
Oxytocin release
What are the 3 stages of labour?
1st: Cervical dilation (8-24 hrs)
2nd: Passage through birth canal (few to 30 mins)
3rd: Expulsion of placenta
What does estrogen do to the breasts?
Growth of ductile system
What does prgesterone help develop?
Lobule-alveolar system
What do estrogen and progesterone inhibit?
Milk production
What does prolactin stimulate?
Milk production
