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Nutrition through life Part 1 > PART 2 - Embryology and Teratology > Flashcards

PART 2 - Embryology and Teratology Flashcards

1
Q

What is teratogenesis?

A

production of birth defects

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2
Q

What is a malformation? What are the 3 types?

A

non-reversible morphological defect present at birth.
exterior: visible
Interior: organs
Microscopic: tiny

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3
Q

What is a congenital abnormality?

A

present at birth regardless of cause

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4
Q

TRUE OR FALSE. All defects lead to death of baby.

A

FALSE. Some can be cured surgically or early in life, some are fatal

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5
Q

TRUE OR FALSE. defects may be symptom-less at birth

A

TRUE

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6
Q

TRUE OR FALSE. Susceptibility to teratogenesis is heavily influenced be the genetics of mother and infant

A

TRUE

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7
Q

What is the most susceptible period of the fetus to teratogenesis?

A

Organogenesis (organogenic period) at 3-8 weeks of pregnancy. dangerous since they don’t know that they are pregnant and the ovum is dividing and differentiating. By the end of this period, the major fetal structures are complete

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8
Q

Why is folate important for those CAPABLE of becoming pregnant?

A

The neural tube closes within 28 days of gestation where most people don’t know they are pregnant

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9
Q

From when do we count the weeks of pregnancy?

A

first day of last menstrual period

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10
Q

What is Hyperplasia and when does it occur?

A

increase cell number (cell division), 17 days to 8 weeks

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11
Q

What is Hypertrophy?

A

increase in cell size

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12
Q

What are the 3 phases of growth?

A

1: Hyperplasia (teratogenic vulnerability)
2: Hypertrophy + Hyperplasia
3: Hypertrophy (risk of organ or biochemical malfunctions)

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13
Q

What is happens when interfering with the hyperplasia phase?

A

Permanent reduction in cell number

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14
Q

Describe the implantation process starting from ovulation

A

Ovulation: Ovum expelled from ovaries into Fallopian tubes
Fertilization: Sperm penetrate oocyte to make zygote
Blastogenesis: zygote begins to cleave and increase cell number (not size) to form the morula
Cavity called blastocele then forms in cell. Now called blastocyst
Blastocyst: -embryoblast: inner cell mass
-trophoblast: outside
Trophoblast cells secrete proteolytic enzymes that erode epithelial uterine lining to create implantation site
Histiotrophic nutritional phase: fluid and nutrients absorbed by phagocytosis
Trophoblast forms a cord of cells –> endometrium and start forming the placenta

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15
Q

The effect of toxicants depend on what?

A

type, dose and length

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16
Q

TRUE OR FALSE. During the blastogenesis phase the zygote does not increase in size.

A

TRUE only in cell number

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17
Q

TRUE OR FALSE. Before implantation there is a decreased exposure to toxins.

A

TRUE, question of accessibility

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18
Q

What is the first step of embryo development?

A

gastrulation. 2-3 weeks

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19
Q

What is Henson’s node?

A

invagination in the future cranial area of the ectoderm (moves caudally)

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20
Q

What are the 3 germ layers formed in gastrulation?

A

ectoderm, Mesoderm, Endoderm

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21
Q

What does the ectoderm become?

A

Brain, CNS, Skin

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22
Q

What does the mesoderm become?

A

Voluntary muscles, CV and excretory systems

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23
Q

What does the Endoderm become?

A

digestive and respiratory systems, glandular organs

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24
Q

Is the gastrulation phase susceptable to teratogenesis?

A

Yes, very.

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25
What is the primitive streak?
Henson's node before it forms the CNS. The cells migrate using this to get where they have to be.
26
What happens to each of the germ layers during and after migration through the primitive streak?
Mesoderm and endoderm migrate internally to make organs and tissues. Then neurulation: ectoderm differentiates into neural plate, the neural tube
27
What happens during neurulation?
Neural plate folds to make neural groove. Then the neural crest cells fuse then separate to make the spinal cord and face/skull
28
When does the heart start beating and the general shape of the embryo is established?
27-29 days post-ovulation (before organogenesis)
29
When is the embryo officially considered a fetus?
When all essential external and internal structures are present, the placenta has developed 8th week of gestation.
30
What is the fetal/neonatal period?
8 weeks to birth tissue differentiation, growth and physical maturation little differentiation of organs except external genatalia
31
What happens when the fetus is exposed to toxins in the fetal/neonatal period?
affects growth and functional maturation CNS and reproductive abnormalities behavioral and motor deficits
32
TRUE OR FALSE. All organs are equally susceptible to teratogenesis during pregnancy.
FALSE. each organ and tissue has its own critical period of growth. that is why timing of exposure is important.
33
What are the 7 classes of teratogens?
Medications, social drugs, environmental agents, temperature (or fever), infectious diseases, chronic disease, nutrient deficiencies and excesses
34
TRUE OR FALSE. Almost all medications cross the placenta.
TRUE
35
What effects does an excess of iodides have on the baby?
congenital goiter, mental/physical retardation
36
What effects does an excess of fluoride have on the baby?
spina bifida occulta
37
What does an excess of vitamin D have on the baby?
facial abnormalities, mental retardation
38
what does an excess of vitamin A have on the baby?
CNS abnormalities (NTD)
39
An excess of vitamin A has negative effects on the baby, but depends highly on the timing of the intake? At what time during the pregnancy is there the most effect?
First 8 weeks, later not much effect shown
40
What effect on the baby does a deficiency of protein have? (extreme)
Microcephaly (small head and brain)
41
What effect on the baby does a deficiency of vitamin A have?
eye abnormalities, microcephaly
42
What effect on the baby does a deficiency of vitamin D have?
Fetal rickets
43
A vitamin D deficiency can cause hypoplasia of the tooth enamel, decreased bone density and growth failure, why?
Not enough calcium available to fetus
44
What effect on the baby does a deficiency of vitamin E have?
a variety of congenital abnormalities
45
What effect on the baby does a deficiency of vitamin K have?
Coumadin syndrome
46
Vitamin K is easily obtained from the diet, in what situation would there be a deficiency?
When the mother takes anticoagulants
47
``` Smoking can decrease the body stores of which vitamin? A-vitamin D B-vitamin E C- vitamin C D- vitaminK ```
B-vitamin E
48
What effect on the baby does a deficiency of folate have?
neural tube defects
49
What effect on the baby does a deficiency of iodine have?
Cretinism (mental/physical retardation)
50
What effect on the baby does a deficiency of potassium have?
kidney abnormalities
51
What effect on the baby does a deficiency of copper have?
connective tissue defects, brain and bone abnormalities
52
What effect on the baby does a deficiency of Zinc have?
neural tube defects
53
In what situation can there be a copper deficiency?
genetic: Menkes kinky hair syndrome, errors in copper metabolism drug that kellates copper and makes it unavailable to fetus
54
What disorder is characterized by an inability to absorb zinc? What are its symptoms?
Acrodermatitis enteropathica, rashes hair loss, diarrhea and poor growth
55
Since its unethical to experiment with deficiencies on pregnant women, how do we know the effects of zinc deficiency?
Acrodermatitis enteropathica
56
The intake of drugs that act as antagonists to certain nutrients can lead to deficiency. Which nutrients are at risk by what type of drug?
folate: folate antagonists Vitamin K: coumadin (coagulant) folate+zinc: anti-convulsant
57
What does FAS stand for?
Fetal alcohol syndrome
58
What are the effects of FAS?
neurological abnormalities, development delay, behavior dysfunction/deficit, intellectual impairment, structural abnormalities
59
What facial abnormalities doe babies with FAS have?
short eye lids, elongated mid-face, thin upper lip, receding jaw
60
TRUE or FALSE. drinking alcohol during pregnancy leads to same result regardless of dose.
FALSE. dose-response relationship
61
TRUE or FALSE. The equivalent of 1 shot glass of pure alcohol spread out during the pregnancy is enough to lead to the early symptoms of FAS.
FALSE. the nontoxic level of alcohol is not known
62
What does ARBD stand for and when is this used?
alcohol related birth defects. used when there is no neural disorder
63
Why does alcohol have such a powerful effect on the fetus?
- women have less gastric alcohol dehydrogenase. so alcohol has greater effect. - alcohol crosses placenta freely - the embryo has small body weight but equal alcohol concentration as the mother - detoxification process not fully developed in embryo - embryo still developing CNS
64
Why is alcohol so toxic?
- has caloric value and replaces calories from other sources - effect on folic acid and zinc metabolism - turns into acetaldehyde (toxic at even lower concentration) - free radicals
65
What does the type of NTD depend on?
depends on the location on the neural tube where the defect occurs
66
What is Anencephaly?
brain is exposed, no skull
67
What is exencephaly?
brain is outside the skull
68
Which is the most common NTD?
Spina Bifida, spine doesn't close
69
TRUE or FALSE. Survival is possible with spina bifida.
TRUE. but permanent damage
70
TRUE or FALSE. NTD are related to a genetic susceptibility.
TRUE
71
What are the possible causes of NTD?
- genetics - teratogens - maternal IDDM (insulin dependent diabetes mellitus) - overweight - high temp - folate deficiency or problem with folate metabolism
72
What is the most prevalent cause of NTD?
Folate related
73
What is homocysteine?
an AA, not used in protein synthesis. is an intermediate in the metabolism of methionine
74
Methionine is transformed into what?
S-adenosyl-methionine (SAM) by a transferase
75
What is the use of SAM (S-adenosyl-methionine)?
Used by the enzyme methyltransferase to methylate different molecules.
76
What is the use of methylation?
- Can silence or activate genes in epigenetic modification processes (change how genes are expressed through methylation) - protein modification (change protein function)
77
What happens to SAM (S-adenosyl-methionine) after it looses its methyl group?
Turns into S-adenosyl-homocysteine (SAH)
78
How do you make homocysteine?
Remove adenosine from SAH (S-adenosyl-homocysteine)
79
What does high levels of homocysteine mean?
homocysteine levels are usually low so high levels means there is a problem
80
What nutrients are needed to replenish methionine?
B12 and folate (through a B12 and folate dependent pathway)
81
What vitamin is needed to make Cysteine?
B6
82
What can homocysteine be used for?
replenish methionine or make cysteine
83
What is the most common cause of having increased homocysteine?
Usually because the system to remethylate homocysteine back to methionine is impaired due to a folate deficiency
84
How does high vitamin A affect the homocysteine pathway?
May suppress the enzyme 5-methylenetetrahydrofolate reductase, which regenerates the methyl donor for homocysteine, so less capacity of regenerating methionine
85
Describe the folate pathway
TH4-Folate --> 5-methylene-TH4-Folate --> [5-methylenetetrahydrofolate reductase] 5-Me-TH4-Folate -->back to beginning after donating methyl to homocysteine with enzyme methionine synthase
86
B12 is a cofactor to which enzyme?
Methionine synthase
87
B6 is the cofactor to which enzyme?
cystathionase in cysteine pathway
88
Describe the cysteine pathway.
Homocysteine -->Cystathionine --> [cystathionase] Cysteine
89
In what context could there be an accumulation of SAH (S-adenosyl-homocysteine)?
a huge rate of gene expression meaning a big rate of methyl transfers. the cycle gets backed up
90
Oxidative stress can lead to limiting the availability of which vitamin? This in turn limits the functional activity of which enzyme?
B12, methionine synthase
91
Pregnant women with NTD babies tend to have characteristic levels of folate and homocysteine i nthe blood. Compare to regular levels.
HIGH homocysteine and LOW folate
92
What complications can happen with high homocysteine levels?
risk factor for preeclampsia, spontaneous abortion, recurrent early miscarriages
93
What is preeclampsia?
High homocysteine--> high BP, damage to certain organs
94
TRUE or FALSE. Maternal homocysteine levels are inversely related to birth weight.
TRUE
95
TRUE or FALSE. There is no correlation between homocysteine levels before and during pregnancy.
FALSE. high before=high during. pre-conceptional may predict homocysteine related pregnancy complications
96
TRUE or FALSE. The synthetic form of folate is more stable and more easily absorbed than the natural form.
TRUE. the synthetic form is already as monoglutamate. no need to transform from natural polyglutamate

Nutrition through life Part 1 (6 decks)

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