Placental Metabolism Flashcards
1
Q
When does the placenta grow the fastest?
A
1st half of pregnancy
2
Q
What is exchanged at the placenta?
A
- nutrients
- respiratory gases
- metabolic waste
- protection of fetus
- sources of hormones
3
Q
What part of the baby is attached to the placenta?
A
umbilical cord
4
Q
How do the babies arteries make their way into the placenta?
A
they divide into vessels which branch into placental villi
5
Q
What are4 benefits of amniotic fluid?
A
- Shock absorber
- prevents desiccation (drying up) of fetus
- provides room for fetal movements
- assists in body temperature regulation
6
Q
What are cytotrophoblasts?
A
cells from placenta that connect mother and fetus
7
Q
What anchors fetal and maternal placenta?
A
cytotrophoblastic shell & anchoring villi – large area for exchange of material
8
Q
Deoxygenated blood leaves fetus and enters placenta via what?
A
umbilical artery
9
Q
How do the fetus arteries divide in the placenta? Then what do they branch into?
A
radially (from centre) & branch into chorionic plate, forming vili
10
Q
Where does the maternal blood flow in the placenta?
A
in intervillous spaces around the villi
11
Q
What is the major functioning unit of the placenta?
A
Chorionic villus
12
Q
How is the placental villus of intrauterine growth restriction (IUGR) infants different from normal infants?
A
IUGR infants have microscopically less branding of villi
13
Q
What brings oxygenated blood and nutrients to fetus?
A
umbilical vein
14
Q
What are the two main functions of the placenta?
A
- metabolism
2. function
15
Q
What 3 things does the placenta metabolize for the fetus?
A
- glycogen
- lactate
- cholesterol
16
Q
___% of O2 and ___% of glucose of maternal blood is used up for the fetus.
A
50%
65%
17
Q
Why is the placental membrane considered a “barrier”?
A
compounds with large M.W. can not cross.
18
Q
What human body part is the placenta relatively similar to?
A
small intestine
19
Q
How does oxygen and many drugs move across the placental membrane?
A
passive diffusion
20
Q
Does fetal hemoglobin have a greater or weaker binding capacity for O2?
A
greater
21
Q
What substances enter the placenta via:
- Passive diffusion
- Facilitated diffusion
- Active transport
- Solvent drag
A
- Oxygen, CO2, FAs, steroids, electrolytes, fat soluble vitamins
- sugars, long chain polyunsaturated FA
- AAs, cations (Ca, Fe, I, PO4), water soluble vitamins
- electrolytes
22
Q
Of the molecules that enter the placenta via passive diffusion, which is poorly transferred?
A
fat soluble vitamins
23
Q
Why do sugars undergo carrier mediated facilitated diffusion?
A
–
24
Q
_______ is a mechanism of teratogenesis
A
glycation
25
What two molecules enter the placenta via pinocytosis?
Fe, folate
26
Step by step, how does maternal malnutrition lead to fetal growth retardation?
Maternal malnutrition --> reduced blood volume expansion --> inadequate increase in cardiac output --> decreased placental blood flow (hypotension, renal disease, placental inflation) --> decreased placental size + reduced nutrient transfer --> fetal growth retardation
27
Fetal size is proportional to _____ size.
placental
28
By how much do the fetus and placenta increase in weight during the 3rd trimester?
fetus: more than 50% (last 10 weeks)
placenta: only 50%
29
How does the placenta compensate for the fact that it increases by a lower rate than the fetus?
placental blood flow increases
30
What happens during the last 4 weeks of gestation?
progressive decline in quantity of nutrients transferred per unit fetal body mass per unit time
31
How does the progressive decline in quantity of nutrients transferred from placenta to fetus during the last 4 weeks of gestation affect fetal growth rate?
deceleration in fetal growth rate.
32
What 3 things happens if the placenta fails?
1. severe hypotension
2. renal disease
3. placental infraction (interruption of blood flow between placenta and baby)
4. essential fatty acid deficiencies which leads to defects in placental function
33
What can placental defects lead to in the baby?
intrauterine fetal growth restriction
34
What is a low concentration of essential fatty acid absorption via placenta associated with?
1. short gestation
| 2. small head circumference
35
Poly unsaturated fatty acids make up what % of energy devoted to brain development?
70%
36
Lipids make up what % of brain structure matter?
50-60%
37
What are the two most common poly unsaturated fatty acids found in the brain motor cortex of mammals?
1. 20:4 n-6 (15%) - linoleic
| 2. 22:6 n-3 (21%) - DHA
38
What are the 4 main functions of the placenta?
1. endocrine (hormone secretion)
2. hormone catabolism
3. nutrient storage
4. protection against xenobiotics
39
What 4 endocrine products does the placenta secrete?
1. human chorionic gonadotrophin (maintains corpus luteum which secretes estrogen & progesterone)
2. human chorionic somatotrophin (placental lactogen)
3. progesterone
4. estrogen
40
1. When is human chorionic gonadotrophin secreted by blastocyst?
2. When is its peak secretion period via placenta?
1. day 7
| 2. day 10 & 11
41
1. When is human placental lactogen (chorionic somatotrophin) secreted?
2. What does it do?
1. late gestation
| 2. it breaks down maternal fats for fuel - influences fat and CHO metabolism
42
What is the function of Human Chorionic Gonadotrophin?
holds up corpus luteum (which secretes estrogen and progesterone)
43
What secretes Human Chorionic Gonadotrophin and when? When is its peak secretion?
Blastocyst secretes it on day 7
Once implantation has occurred, the placenta produces it. Peak secretion via placenta on week 10
44
What produces progesterone and when?
- Corpus luteum - 1st 10 weeks
| - Placenta - post 10 weeks
45
What are the two functions of progesterone?
1. inhibit secretion of pituitary gonadotrophin (LH & FSH) to prevent ovulation and supports the endometrium
2. suppresses contractility in uterine smooth muscle
46
When is estrogen maximally secreted?
during end of gestation
47
What does estrogen stimulate? antagonize?
1. stimulates myometrium growth / mammary gland development
| 2. antagonizes myocetrial suppression by progesterone
48
How does the placenta largely control the access of glucocorticoids, insulin and thyroxine to fetal tissues?
by metabolizing them to their inactive form when they are not needed
49
The fact that the placenta s highly permeable to a large variety of substances causes limited protection against what?
xenobiotics
50
What are the 6 physiological adjustments that occur during pregnancy?
1. increased blood volume
2. altered stomach, cardiac, renal and pulmonary (lungs) functions
3. hemodilution (decreased concentration of cells and solids in the blood resulting from gain of fluid)
4. altered plasma lipid profiles
5. altered appetite and thirst
6. altered digestion and assimilation of food
51
Pregnancy - renal:
Increase or decrease?
_______ glomerulus filtration rate and _______ tubular re-absorption capacity leads to ________ excretion of fetal waste products but ALSO ________ renal loss of glucose, folate, iodine, and aa's.
1. increase
2. decreased
3. increased
4. increased
52
What happens to histamine and pepsin during pregnancy?
decreased production
53
Pregnant woman - heart:
1. Why may a woman experience heartburn?
2. Cardiac hypertrophy + _______ cardiac output.
1. due to a relaxed cardiac sphincter
| 2. increased
54
Pregnancy - GI tract:
Increase or decrease?
_______ GI motility + insufficient fluids leads to _______ risk of constipation.
1. decreased
| 2. increased
55
During pregnancy - lungs:
Increase of decrease?
______ ventilation due to ______ oxygen demands.
1. increased
| 2. increased
56
Pregnant woman - blood:
1. _________ plasma lipids. Why?
2. Blood glucose _______ in 3rd trimester but ________ lipolysis and mild ketosis.
1. increase in order to conserve glucose
| 2. decreases, increase
57
Pregnant woman - muscle:
_______ muscle breakdown + ________ placental uptake of alanine leads to ________ alanine availability which leads to ________ hepatic gluconeogenesis.
1. decreased
2. increased
3. decreased
4. impaired (decreased)
58
During early and late pregnancy, are the mother/fetus anabolic or catabolic?
Early:
Mother = anabolic
Fetus = anabolic
Late:
Mother = catabolic
Fetus = anabolic
59
Describe the fuel disposition (CHO, fat, protein) of the mother during early and late gestation
Early - Anabolic:
1. extra CHO stored as glycogen or converted to fat (sharp rise in postprandial (right after a meal) blood insulin)
2. Fats rapidly synthesized to TGs
3. Increased maternal protein synthesis
Late - Catabolic:
1. fat mobilized to conserve glucose for fetus
2. Increase ketones, increase blood cholesterol (increased synthesis and decreased breakdown)
3. postprandial (post-meal) insulin action blunted by estrogen, progesterone, placental lactogen leads to catabolism of maternal fat, glycogen & protein
4. glucose increase for greater uptake by placenta (does not rely on insulin)
60
What is the total recommended weight gain for pregnant women:
1. <20
2. 20-27
3. >27
1. 12.5 - 18 kg
2. 11.5 - 16 kg
3. 7 - 11.5 kg
61
Once you become pregnant what % of your body weight should be fat?
22%
62
If the BMI of a pregnant woman is >29, what should she limit her wait gain to?
6 kg
63
If a woman is pregnant with twins, how much wait should she gain no matter what?
35-45 lbs
64
What is the recommended pattern of weight gain for people?
3-4 lbs for 1st 10 weeks, then 1 lb/week for rest of pregnancy
65
If a pregnant woman gains more than 1 kg/week, this likely means what?
excessive edema, risk for preeclampsia (high blood pressure and signs of damage to liver/kidneys) which may lead to increased risk of placental abruption, stillbirth, decreased blood flow to placenta, lean body weight
66
What 5 body parts contribute to weight gain no matter what during pregnancy?
1. fetus
2. placenta
3. enlarged uterine
4. enlarged breast tissue
5. expanded blood volume
67
What 3 things is insufficient blood volume during pregnancy correlated with?
1. still birth
2. lean body weight
3. spontaneous abortions
68
What is common during pregnancy?
edema
69
Avg. ____ kg fat laid down by 30 weeks of pregnancy
3.8
70
___% of energy needed to support pregnancy is deposited in 1st 20 weeks
40%
71
1/3 of maternal weight gain =
2/3 of maternal weight gain =
1/3 = fetal tissues, placenta & amniotic fluid
2/3 = maternal tissue accretion (growth), expansion of maternal blood volume, extracellular fluid, fat/protein stores
72
There is a ______ correlation between plasma volume/RBC and fetal size.
direct
73
What type of weight gain/loss is normal in the 1st trimester?
weight maintenance or slight loss - little effect on embryonic weight gain
74
When does morning sickness normally start? Why?
6 weeks after last menstrual period due to increased estrogen and human chorionic gonadotrophin
75
What is nausea/vomiting a GOOD sign of during pregnancy?
positive pregnancy outcome & decreased risk of fetal death
76
Too many skipped meals during pregnancy will lead t what?
ketosis & hypoglycaemia (teratogenic risk)
77
What type of diet is recommended during pregnancy?
small frequent high fat, low bulk meals
78
What are the 3 most important determinants of birth weight?
1. gestational age
2. maternal weight gain
3. preconception weight
79
Mortality rates are lowest for infants between ___kg and ___kg.
2.5 kg & 4 kg
80
What is the best clinical indicator to judge pregnancy progress and is also the best indicator on fetal weight gain?
maternal weight gain
81
Dietary restrictions increase the risk of what 4 things?
1. low birth weight
2. hypertension
3. perinatal mortality
4. intrauterine growth restriction
82
Highest perinatal mortality rates in _______ women who gain ______ weight.
1. underweight
| 2. little
83
Obese pregnant women have a higher risk of what?
1. preeclampsia (high blood pressure and signs of liver and kidney damage)
2. Gestational diabetes mellitus
3. infection
4. Caesarian (C) section
84
Excessive weight gain during pregnancy may lead to what 2 complications during delivery?
1. asphyxia (when the body is deprived of oxygen, causing unconsciousness or death)
2. abnormal glucose blood regulation in infant
85
What is the WHO definition of preterm birth?
| Week + 3 factors
< or = 37 weeks
1. if a baby is less than 2 SDs in weight for gestational age
2. less than 10th percentile in weight for gestational age
3. less than 2500 g and gestational age is greater than 37 weeks
86
What is the most serious disorder that a premature baby can be born with?
neurocognitive (ex. cerebral palsy, mental retardation, seizure disorder)
87
What is the WHO definition of low birth weight?
less than 2500 g
88
What two things is birth weight determined by?
1. duration of gestation
| 2. rate of fetal growth
89
What are 7 causes of preterm births?
1. genital infection
2. multiple pregnancy
3. pregnancy-induced hypertension
4. low pregnancy BMI
5. prior history
6. smoking
7. strenuous physical labor
90
A low birth weight in a baby may be due to what two things?
1. preterm birth
| 2. small for gestational age
91
What 6 things determine intrauterine growth restrictions?
1. low energy intake
2. low prepregnancy BMI
3. short maternal stature
4. pregnancy-induced HTN
5. smoking
6. malaria
92
_______ is a major cause of anemia in primiparous (giving birth for 1st time) women
primiparous
93
Intrauterine growth restriction may lead to ________ and ________ in early neonatal period.
1. hypoglycaemia
2. hypocalcemia
risk of infection
94
What are 3 abnormal patterns of fetal growth that is linked to adult disease?
1. symmetrical small babies of low birth weight
2. babies thin at birth but undergo catch-up later in infancy (disproportionally large head & narrow waist)
3. average birth weight infants but abnormally small in proportion to their placental weight - then grow below avg during pregnancy
95
Intrauterine growth retardation has been recently associated with what 3 adult diseases?
1. hypertension
2. type 2 diabetes
3. coronary heart disease
96
What are 4 effects that a baby with a low birth weight may experience later in life?
1. decreased lung capacity during childhood
2. twice the risk of cardiovascular disease
3. 6x the risk of diabetes and impaired glucose metabolism
4. increased blood pressure risk, abnormal high triglycerides&insulin, low HDL
97
What is considered an excessive birth weight? What is it linked with?
> 9 lbs - increased risk of hormonally related cancers
98
Can improved post-natal nutrition correct metabolic abnormalities in adulthood?
no
99
How is poverty correlated to nutritional risk for pregnancy?
1. poorer nutritional intake/status
2. increased smoking
3. 2x LBW (decreased by 200-300g)
100
How is adolescence correlated to nutritional risk for pregnancy?
high nutritional demands / food fads / poor financial status - increased use of drugs & smoking
101
What are 5 chronic systemic illnesses that pose a high nutritional risk for pregnancy?
1. diabetes
2. chronic infection
3. cancer
4. alcoholism
5. malabsorption
