placental metabolism Flashcards
what is a placenta?
circular shaped organ that is important for sharing the circulatory system between mom and kid so that nutrients, gases, hormones, and waste products can be exchanged. portion from embryo and portion from mom’s uterus
true or false: an embryo and mom share blood
false; the fetus and mother have separate systems but there are villi where the exchange can happen
when is the development of the placenta fastest? implications?
first half of pregnancy
any complications during this time can have
maternal venule
site where waste products and co2 are sent out from the fetus
maternal arteriole
site where oxygenated blood
placental functions (2):
- metabolism (synth of glycogen, lactate, cholesterol)
- transport
- endocrine
- hormone metabolism
- nutrient storage
- protection against xenobiotics
what percentage of oxygen and glucose uptaken by the placenta is used by the placenta?
65% glucose
up to 50% oxygen
what substances can be transported by the placenta?
- nutrients
- immunoglobulins (passive immunity)
- harmful substances
- waste products
mechanisms of transport in the placenta?
- passive (gases, electrolytes, fat-solubles)
- facilitated (sugars, long chain PUFAs)
- active (AAs, cations)
- solvent drag (electrolytes)
the placental carriers for PUFAs are (uni/bi - directional)
uni
if the mom has diabetes, will the fetus be protected from excess blood sugars?
yes - the glucose transporters will be saturated, blocking sugars from reaching the same concentrations in the fetus
that said, hyperglycemia is still considered teratogenic. late in the pregnancy it is also associated with excessive growth of the fetus.
what happens if the mom is malnourished
reduces blood volume
- -> cardiac output decreased
- -> decreased placental blood flow
- -> decreased placenta size and decreased nutrient transfer
- -> retardation of fetal growth
what happens to the placenta in the 3rd trimester?
- fetus grows fast so placenta increases blood flow to compensate. placental growth is increased by 50%
- progressive decline in quantity of nutrients transferred, contributing to decelerated growth rate
why is having a pregnancy that is too long dangerous?
placenta can no longer compensate optimal nutrient and oxygen needs of the fetus
what kind of maternal conditions can lead to placental failure?
- severe hypotension
- renal disease
- EFA deficiencies
what’s a placental infarction?
death of placental tissue
can be due to exposure to harmful substances like cigarette smoke
main role of eicosanoids in pregnancy?
maintaining blood flow between mom and placenta
what is glycation?
enzymatic covalent bonding between protein and glucose; closely linked to the pathogenesis of diabetes
what is biomagnification as it pertains to DHAs?
there’s selected transfer DHAs from maternal system ultimately to the fetal brain so that concentrations go up so that the brain can accumulate these DHAs
what makes PUFAs relevant?
- contribution to membrane fluidity –> better transmission of nerve signals
- brain is made of this
what is the relevance of ketone bodies?
- natural state of pregnancy is to induce some insulin resistance so that lipids sources of energy can be delivered to the placenta
- this can also increase the ketones that make it to the placenta which is fine during the 3rd trimester to some extent, but risky in earlier pregnancy
what kind of adjustments are seen during pregnancy?
- increased blood volume
- altered stomach, cardiac, renal, and pulmonary functions
- hemodilution
- altered plasma lipid profiles
- altered appetite and thirst
- altered digestion and assimilation of food
in early pregnancy, the mother undergoes the (anabolic/catabolic) phase and the fetus undergoes the (catabolic/anabolic) phase
mother: anabolic
fetus: anabolic
in late pregnancy, the mother undergoes the (anabolic/catabolic) phase and the fetus undergoes the (catabolic/anabolic) phase
mother: catabolic
fetus: anabolic
weight gain required for those with BMI under 20?
12.5 to 18 kg
weight gain required for those with a BMI between 20-27?
11.5 to 16 kg
weight gain required for those with a BMI over 27?
7 to 11.5 kg
when does most of the weight gain happen?
second half of pregnancy; really takes off in the last trimester
why are the mom’s fat stores important?
- protect from energy deficits
- important during lactation
how much weight gain do we see in the first trimester?
minimal
most important determinants of birth weight
- gestational age
- maternal weight gain
- preconception weight
in what weight range is infant mortality rate lowest?
2.5 to 4 kg
what are some abnormal growth patterns linked to adult diseases?
- lbw, symmetrical babies
- lbw but catch-up later (disproportionally large head, narrow waist)
- normal bw that grow slowly during infancy
long-term health risks associated with lbw
- decreased lung capacity during childhood
- x2 risk of cvd
- x6 risk of diabetes/impaired glucose metabolism
- increased bp risk, abnormal high TG, insulin and low HDL
long-term health risks for excessive bw?
- risk of hormonally related cancers
- obesity
why is heart disease risk increased w/LBW?
liver cholesterol metabolism is hampered
why the risks for LBW infants?
undernourished mom = stress –> release cortisol (steroid)
good for development of organs (short term), bad for hypertension (long term)
what happens to protein metabolism when the mom is undernourished?
IGF-1 is suppressed shifting AA metabolism for energy rather than protein synthesis
categories for nutritional risk for pregnancy (8)
- poverty
- low pre-preg and preg weight
- short interconception interval
- chronic systemic illness
- unusual dietary patterns (like eating sand)
- history of anemia or obesity
- poor reproductive history
- adolescence
what’s the recommended PAL?
1.6-1.7 (active)
what happens to BEE and PAL when preg?
BEE increases
PAL decreases
what happens to TEE during preg?
increase by 8 kcal/gestational week
protein rq during preg?
needs to support GROWTH depends on trimester 1) growth, tissue deposition 2) increased growth 3) mega high growth (includes placenta)
RDA for preg woman = 25 g/d of additional protein
what happens if u don’t have enough protein during pregnancy?
increased risk of LBW
the requirement for N-6 fatty acids (increases/decreases) during preganancy
increase
AI = 13 g/day. median intakes are shown to be sufficient
when is the median intake for EFAs insufficient for pregnant women?
when overall energy intake is insufficient
when is n-9 FA (mead) higher?
when n-6 and n-3 are low
vegetarians have (higher/lower) amounts of arachidonic acid and (higher/lower) amounts of docosahexaenoic acid compared to omnivores
arachidonic: higher
DHA: lower
the pregnant state (increases/decreases) CHO requirements
increases
why does the pregnant state increase CHO requirement
- establishment of placental-fetal unit
- energy supply for growth and development of fetus
- establishment of maternal fat stores in EARLY pregnancy
- energy to sustain growth of fetus during the last trimester
how much glucose is transferred from mother to fetus in late gestation?
17-26 g/d
true or false: the fetal brain uses ketoacids
true - up 30% of fuel
32.5 g
fiber requirement (increases/decreases) in the pregnant state
neither - there’s no evidence that there’s a different beneficial effect
28 g/d
what is the AI for water in the preg state based on?
median intakes
total intake is 3 L/d
