Physiology of pregnancy Flashcards
Around which days, does the blastocyst attach to the lining of the uterus?
Days 5-8
The blastocyst becomes completely buried in the uterine lining by which day?
Day 12
The placenta is derived from which tissues?
Trophoblast and decidua
The trophoblast cells (chorion) differentiate into what?
Syncytiotrophoblasts (multi-nucleated cells)
These invade the decidua and break down capillaries to form cavities filled with maternal blood
By which week of pregnancy is the PLACENTA and foetal heart functional?
5th week of pregnancy
Where does the embryo get its nutrition from in early development?
Trophoblastic cells (these invade decidua)
Progesterone stimulates decidual cells to concentrate glycogen, proteins and lipids
HCG does what to corpus luteum?
Stops the corpus luteum from breaking down
(corpus luteum to continue secreting progesterone etc)
(progesterone stimulates decidual cells to concentrate glycogen, proteins and lipids)
Which organ acts as a physiological arteriovenous shunt?
The placenta
circulation within the intervillous space acts partly as an ateriovenous shunt
Which organ plays the role of the “fetal lungs”
The placentah
The supply of the fetus with oxygen is facilitated by which 3 factors?
1) fetal Hb (increased ability to carry O2)
2) higher Hb concentration in fetal blood (50% more than adults)
3) Bohr effect (fetal Hb can carry more oxygen in low pCo2 than in high pCo2)
How do fatty acids pass through placenta?
Free diffusion
How does glucose pass through the placenta?
Simplified transport
What is the fetus’s main source of energy? And which trimester is there a high need for this substance?
Glucose
high glucose need in 3rd trimester
What is the trophoblast?
The surface layer of cells of the blastocyst
What passes through the umbilical veins?
Oxygen saturated blood to fetus
What passes through the uterine veins?
Oxygen poor blood (from fetus to mother)
How are electrolytes transported across the placenta?
Electrolytes follow water (iron and calcium only go from mother to child)
HCG effect on male fetus?
Development of sex organs
When is human chorionic somatomammotropin produced in pregnancy?
Produced from week 5
What does human chorionic somatomammotrophin do?
It has growth hormone like effects - protein tissue formation
- decreases insulin sensitivity in mother SO THERE IS MORE GLUCOSE FOR THE FETUS
- involved in breast development and possible lactation
Which hormone is responsible for:
- development of decidual cells
- decreases uterus contractility
- preparation for lactation?
Progesterone
Progesterone and decidual cells
Progesterone causes development of decidual cells
Progesterone and uterus contractility?
Progesterone decreases uterus contractility
Progesterone and lactation
Progesterone helps with preparation for lactation
Which hormone causes:
- enlargement of uterus
- breast development
- relaxation of ligaments?
Estrogen
Which hormone is an indicator of the vitality of the fetus?
Estriol
Estrogen and breasts?
Estrogen causes breast development
Cardiac output and pregnancy?
Cardiac output increases (beginning week 6 and peaking around week 24)
(decreases in the last 8 weeks as becomes sensitive to body position - uterus compresses vena cava)
Iron requirements for 2nd half of pregnancy
6-7mg per day
How do the following change in pregnancy:
- plasma volume
- erythropoesis (RBC)
- Hb concentration
- Plasma volume increases proportionally with cardiac output (50%)
- erythropoesis increases (25%)
-although both are increasing, plasma volume increases more so Hb concentration is diluted (this decreases blood viscosity)
Why do you get odema in pre-eclampsia?
Kidney function declines and you get salt and water retention (function probably declines because of high blood pressure or something)
Is pre-eclampsia more common in women with a single baby or twins?
More common in multiple gestation (e.g. twins)
Average weight gain in pregnancy?
24lbs (fetus - 5kg, mother -6kg)
How many extra calories a day does the mother need?
250-300 extra calories
How much extra protein does the mother need?
30g
When is the mother’s anabolic phase?
1st-20th week of pregnancy
- anabolic metabolism of mother
- quite small nutritional demands of the mother
When does accelerated starvation of the mother occur?
catabolic phase
21-40th week of pregnancy (especially 3rd trimester)
- high metabolic demands of fetus
- accelerated starvation of mother
Which hormones are responsible for insulin resistance in pregnancy?
HCS, cortisol and growth hormone
Does the following occur in the anabolic or catabolic phase of pregnancy?
- normal or increased sensitivity to insulin
- lower plasmatic glucose level
- lipogenesis, glycogen stores increases
- growth of breasts, uterus,weight gain
Anabolic phase
Does the following occur in the anabolic or catabolic phase of pregnancy?
- maternal insulin resistance
- increased transport of nutritients through placental membrane
- lipolysis
Catabolic phase
What iron supplement should the mother take?
300 mg ferrous sulfate
Why does a mother need to take B vitamins?
Erythropoeisis
What does folic acid (folate) help to protect against?
Neural tube defects
When is vitamin K given and why?
Given right before giving birth - helps prevent intracranial bleeding during labour
Estrogen and progesterone and their effects on contractility of the uterus?
- Estrogen increases contractility
- Progesterone decreases contractility
- The ratio of these alter just before giving birth
Where is oxytocin produced?
Maternal posterior pituitary gland
Oxytocin and contractility of uterus?
Oxytocin increases contractions and excitability
Which hormones are responsible for controlling timing of labour?
Oxytocin
Adrenal gland
Prostaglandin
What are braxton hicks contractions?
These are prodromal contractions (like practise ones) they start around week 6 of pregnancy but are not usually felt until 2nd/3rd trimester. They increase towards the end of pregnancy and eventually become real ones
Growth of ductile system
Estrogen
Development of lobule-alveolar system
Progesterone
Estrogen and progesterone effects on milk production
Estrogen and progesterone inhibit milk production
at birth, estrogen and progesterone suddenly drop
Two hormones needed for milk production
Prolactin
Oxytocin (produced by sucking stimulus)
