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nutrition thru life > placental metabolism > Flashcards

placental metabolism Flashcards

1
Q

The placenta is formed from the (maternal/fetal) cells?

A

Both.

From the fetal endometrium cells, and the uterine lining

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2
Q

What purposes does the amniotic fluid serve?

A

Absorbs shock
prevents dessication
allows for movement
regulates temperature

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3
Q

The umbilical artery flows (to/from) the placenta, while the umbilical vein flows (to/from) the fetus.

A

To; to

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4
Q

True/False: The placenta grows steadily throughout preganancy

A

False. Fastest period of growth is in first half of pregnancy, then rate slows down.

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5
Q

What can the placenta synthesize?

A

Cholesterol
Glycogen
Lactate

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6
Q

What purposes does the placenta serve? (6)

A 
Nutrient exchange
Nutrient storage
respiration (Gas exchange)
Hormone production
Protection of fetus
Remove wastes
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7
Q

The fetus circulation is anchored by ____ which allow for exchange.

A

villi

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8
Q

______ cells in the placenta connect the mother and fetus.

A

cytotrophoblasts

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9
Q

If the maternal and fetal blood are not directly in contact, how does exchange occur?

A

Maternal blood flows into the intervilli space, bathing the anchoring villi of the fetal circulation, which can then exchange gases/compounds.

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10
Q

What connects the placenta and the fetus?

A

Umbilical cord

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11
Q

What are the major functioning units of the placenta?

A

Chorionic villi

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12
Q

The _____ plate is on the fetal side of the placenta and is where the umbilical artery branches out.

A

chorionic

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13
Q

What are the implications of less chorionic villi branching?

A

less exchange; possible stunted growth (IUGR infants)

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14
Q

True/False: sugars cross the placenta through passive diffusion

A

False; sugars require FACILITATED diffusion

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15
Q

The placenta can act as a barrier against ____.

A

Large molecular weight compounds (ex: xenobiotics)

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16
Q

The embryo is enclosed in the ____ sac, filled with ____.

A

amniotic; amniotic fluid

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17
Q

True/False: PUFAs must be transported across the placenta by carrier mediated transport.

A

False; PUFAs can utilize passive diffusion but this is insufficient, so carrier mediated is also required.

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18
Q

How does oxygen cross the placenta? What enables this?

A

Passive diffusion

fetal Hb has a greater affinity for oxygen

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19
Q

Where does the amniotic fluid come from?

A

“urine” from fetus

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20
Q

How are fat soluble vitamins transported? To what extent?

A

Passive diffusion; poorly

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21
Q

What solutes require active transport across the placenta?

A

Amino acids
Some ions: Ca, Fe, I, PO4
Water soluble vitamins

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22
Q

How is cholesterol transported?

A

passive diffusion

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23
Q

How are electrolytes transferred?

A

passive diffusion

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24
Q

What is the importance of having carrier mediated glucose transport across the placenta?

A

Protects the fetus from fluctuations in blood glucose levels since requires transporter protein (saturable)
Does not require energy for transport.

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25
Q

How are long chain PUFAs transferred?

A

Carrier mediated diffusion

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26
Q

Why might hyperglycemia be damaging to a fetus?

A

High glucose leads to glycation of molecules, which can be teratogenic.

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27
Q

What other method may be used to transport Folate or Fe?

A

pinocytosis

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28
Q

How does the placenta compensate for lack of growth in the 3rd trimester?

A

Blood flow increases.

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29
Q

How might an Fe deficiency impact the development of the fetus (with regards to placental development)?

A

Fe deficiency -> less cardiac output, decreased placental blood volume/flow -> less placenta growth -> less nutrient transfer -> stunted growth of fetus

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30
Q

True/False: the fetus and placenta grow at the same rate through pregnancy.

A

False: the placenta will grow quickly during the first half, but in the 3rd trimester, the fetus will grow rapidly while the placenta does not change much.

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31
Q

What is the transport mechanism for water (and some solutes)? How does this work?

A

Solvent Drag

creating osmotic pressure

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32
Q

Blood flow in placenta is largely regulated by ____.

A

Eicosanoids

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33
Q

A decline in ____ ____ rate per fetal body mass increases in late pregnancy. How does this affect fetal growth rate?

A

nutrient transfer

decreases growth rate

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34
Q

Placental failure may be due to:

A

Failure to increase blood flow (hypotension, renal disease, infarction/blockage)
EFA deficiencies -> placental defects

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35
Q

What EFA is especially important for the developing fetal brain?

A

DHA

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36
Q

What is a likely cause of morning sickness?

A

huge amounts of hCG secreted by the placenta

37
Q

pregnancy tests detect _______ which is secreted by the _____.

A

hCG (human chorionic gonadotropin)

placenta

38
Q

What serves as the endocrine organ before the placenta is developed?

A

corpus luteum

39
Q

What hormones does the placenta secrete?

A

hCG, hCS, estrogen, progesterone

40
Q

What is the role of hCS, and what secretes it? what does it stand for?

A

Human chorionic somatotropin
lactogen: affects maternal metabolism, breakdown of carbs/fat for fetal use
secreted by placenta

41
Q

What is the role of progesterone during pregnancy?

A
  • Suppress FSH and LH to prevent ovulation

- contract smooth muscle to prevent preterm birth

42
Q

How might excess insulin affect fetal growth?

A

too much growth

43
Q

Why might a healthy pregnant woman have a lowered hematocrit?

A

Hemodilution; increased blood volume but number of cells has yet to compensate.

44
Q

What is the role of estrogen during pregnancy?

A

Rises near the end of pregnancy to antagonize progesterone effects and allow for birth
Stimulate mammary gland development

45
Q

How might glucocorticoids affect fetal growth?

A

adrenal suppression, low birth weight

46
Q

How might thyroxine affect fetal growth?

A

miscarriage or small baby

47
Q

True/False: the mother provides the fetus with insulin, glucocorticoids, and thyroxine, which pass through by passive transport.

A

False. The placenta controls hormone access to the fetus, and metabolizes insulin, glucocorticoids, and thyroxine to inactive forms to prevent excess levels.

48
Q

What are the 2 metabolic phases of pregnancy?

A

Anabolic and Catabolic

49
Q

Why do pregnant women pee more?

A

Higher Glomerular filtration rate in kidneys and less reabsorption to allow for excretion of fetal wastes

50
Q

How is the GI tract affected by pregnancy?

A
  • Less histamine/pepsin -> overall depressed function
  • relaxed cardiac sphincter (heartburn)
  • slower movement through tract
  • more efficient absorption
  • constipation
51
Q

What happens to blood glucose during the 3rd trimester, and what happens as a result?

A

decreases

mild ketosis, lipolysis increases

52
Q

Do plasma lipid levels rise or fall during pregnancy? Why?

A

Rise

Body is using lipids for fuel, to conserve glucose for fetus

53
Q

True/False: The catabolic phase occurs after the anabolic phase

A

True

54
Q

What body systems are stimulated (more active) during pregnancy?

A

Cardiac
Respiratory
Renal

55
Q

Why is hepatic gluconeogenesis impaired during pregnancy?

A

Muscle breakdown decreases, and Alanine (necessary for gluconeogenesis) levels decrease, since it is given to the fetus.

56
Q

Protein is used for synthesis of ____ during the anabolic phase to prepare for greater blood volume.

A

RBCs

57
Q

What is the purpose of the anabolic phase? What occurs?

A

To build up maternal stores to prepare for later pregnancy needs.
High insulin levels
Rapid TG and protein synthesis
Carbs are deposited as fat or glycogen

58
Q

What is the main source of fuel used by the mother during the catabolic phase and why?

A

Lipids; to spare glucose for fetus

59
Q

describe the effects of hCS, estrogen, and progesterone on maternal metabolism during the catabolic phase.

A

Antagonize effect of insulin; less uptake of glucose by mother, and fat catabolism can take place. Glucose is spared for fetal use.

60
Q

What might excessive weight gain signify?

A

Excessive edema, risk of pre-eclampsia, placenta rupture, stillbirth

61
Q

True/False: Weight gain during pregnancy should be less for obese women

A

True

62
Q

True/False: placental uptake of glucose is insulin dependent.

A

False; not regulated by glucose.

63
Q

What should the pattern of weight gain be during pregnancy?

A

3-4lbs in first 10 weeks

1 lb or less per week for remainder

64
Q

What are the non-obligatory sources of weight gain?

A

Protein/fat stores, edema (extracellular fluid)

65
Q

Where is fat stored in first trimester and why?

A

subcutanaceous, in thighs/abdomen

To protect against deficits later on

66
Q

What tissues contribute to obligatory weight gain during pregnancy

A 
Fetus
Placenta
Amniotic Fluid
Enlarged breasts/uterus
Higher blood volume
67
Q

Weight gain should be highest in (early/mid/late) pregnancy

A

Mid-pregnancy

68
Q

Skipping meals could affect the fetus in what ways?

A

Too many skipped meals can lead to hypoglycemia or ketosis, which can be teratogenic

69
Q

True/False: Any weight loss in the first trimester would be a large concern, and can affect the development of the fetus.

A

False; weight in the first trimester usually stays about the same, or may even fall slightly due to morning sickness. This is not of concern since the embryo has limited growth during this time.

70
Q

Perinatal mortality is highest in ____weight women with ___ weight gain.

A

under; low

71
Q

The best clinical indicator of newborn health is _____.

A

Birth weight

72
Q

What factors determine newborn birth weight? What factor has the biggest impact?

A

gestational age
maternal weight gain (biggest factor)
preconception weight

73
Q

True/False: An underweight woman’s pregnancy could have lower risk of complications than a woman with normal BMI.

A

True: an underweight woman with appropriate weight gain will have least risk of complications

74
Q

What are the two outcomes associated with low birth weight?

A

Premature

intrauterine growth retardation

75
Q

Premature infants often have underdeveloped ____. They may be given ____ to help them mature.

A

Respiratory systems; steroids

76
Q

Maternal malnutrition causes ____ IUGR, while severe fetal malnutrition causes ____ IUGR

A

disproportionate

proportionate

77
Q

IUGR infants can be classified as ____ or ____.

A

proportionate or disproportionate

78
Q

Microcephaly is ____ IUGR.

A

Proportionate; head is small but remainder of body and weight are proportionate.

79
Q

What is the difference between proportionate and disproportionate?

A

proportionate: head/length/body/weight all same percentile; all stunted due to extreme malnutrition/toxins/genes
disproportionate: malnutrition - “head sparing:” growth is focused on head and length, weight gain is decreased.

80
Q

Environmental toxins will cause what type of IUGR?

A

proportionate

81
Q

alcohol causes what type of IUGR?

A

disproportionate

82
Q

Is “catch-up” growth possible for IUGR infants?

A

Yes, but usually not completely

83
Q

What conditions (2) are common in IUGR neonates?

A

Hypoglycemia, hypocalcemia

84
Q

What adult diseases have been associated with IUGR infants later in life? Why?

A

Type II diabetes/insulin resistance
Coronary heart disease
Hypertensive heart disease
Infant is susceptible to the programming effects of malnutrition (epigenetic modifications), which affects gene expression; malnutrition will also affect certain hormone levels

85
Q

Why does undernutrition result in higher cortisol exposure for the fetus?

A
  • maternal levels are elevated to accelerate maturation
  • placenta is underdeveloped due to malnutrition, and will be unable to properly break down hormones (thyroxine, corticosteroids, insulin)
86
Q

Excessive birth weight is associated with ______ later in life.

A

hormone related cancers

87
Q

In undernutrition, what hormone will be elevated in the mother? What are the positive and negative effects of this?

A

Corticosteroids
accelerates maturation of the fetus; advantageous for survival
BUT: elevated cortisol exposure associated with hypertension later in life

88
Q

What circumstances increase nutritional risk during pregnancy? (8)

A 
poverty
low pre pregnancy weight
unusual dietary patterns (pica, anorexia, etc)
chronic illness
obesity/anemia - sign of malnutrition
adolescence
poor reproductive history
short inter-conception interval

nutrition thru life (15 decks)

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