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Fundamentals of Patient Management > BSC Embryo 1 > Flashcards

BSC Embryo 1 Flashcards

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1
Q

what are the 3 anatomical planes? describe each

A

1) sagittal plane: vertical plane that divides the body into left and right
2) coronal plane: vertical plane that divides the body into front (anterior) and back (posterior)
3) transverse plane: horizontal plane that divides the body into upper (superior) and lower (inferior)

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2
Q

what are synonyms to superior and inferior?

A

cranial (superior) and caudal (inferior)

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3
Q

what guides embryonic development?

A

the genome

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4
Q

1) how many chromosomes does the human genome possess?
2) how are they arranged?
3)give detail about their sex characteristics

A

1) 46 chromosomes total
2) arranged in 23 pairs (from maternal and paternal parent)
3) 22 autosomal pairs, 1 pair of sex chromosomes

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5
Q

what does 1 gene lead to?

A

many different proteins

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6
Q

what do proteins regulate?

A

gene expression and act as signaling molecules

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7
Q

what is induction? describe what an inducer does

A

one group of cells or tissue causes another to change their fate
- INDUCER PRODUCES A SIGNAL AND RESPONDER REACTS TO THE SIGNAL
- ability to respond is called competence
- this process induces cells to differentiate into the tissues that make up our body

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8
Q

what kind of signaling is essential for induction

A

cell- to- cell

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9
Q

what is paracrine signaling

A

SIGNALING USING DIFFUSIBLE FACTORS
- signaling molecules (LIGAND) is released from cell 1
- RECEPTOR on cell 2 receives signaling molecule

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10
Q

what is an example pathway for embryogenesis (cell-to-cell signaling)

A

SONIC HEDGEHOG (SHH) MASTER GENE OF EMBRYOGENESIS
- involved in development of vasculature, left-right axis formation, cerebellum, neural/ smooth muscle patterning, limbs, heart, gut, pharynx, lungs, pancreas, kidneys, bladder, hair follicles, teeth, thymocytes, inner ear, eyes, and taste buds
- mutation and uncontrolled activation in this pathway has been implicated in cancers and congenital syndromes

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11
Q

what is the extracellular matrix

A
  • substances secreted by cells into the tissue that surrounds them
  • acts as structural support, communication between cells, cell movement and other functions
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12
Q

why is cell-to-cell signaling essential?

A

for induction to continue

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13
Q

which factors do juxtacrine signaling use? what are the 3 types of juxtacrine signaling?

A
  • uses non- diffusible factors
    1) protein on cell 1 SURFACE interacts with receptor on adjacent cell 2 SURFACE
    2) receptor on cell 1 binds to ligand in the ECM SECRETED BY CELL 2
    3) signal is transmitted directly from the cytoplasm of cell 1 through gap junctions into the cytoplasm of adjacent cell 2
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14
Q

what is the term for “small conduits” in cells

A

gap junctions

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15
Q

why do signaling errors may occur

A

genetic or environmental factors or BOTH

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16
Q

what is an example of a signaling error

A

SITUS INVERSUS: CONDITION WHERE THE POSITIONING OF ALL ORGANS IS REVERSED IN A MIRROR IMAGE ARRANGEMENT

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17
Q

what is heterotaxy?

A

ONE OR MORE ORGANS IS ABNORMALLY PLACED

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18
Q

what is gametogenesis

A

THE PROCESS BY WHICH GAMETES (GERM CELLS) ARE PRODUCED IN AN ORGANISM

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19
Q

describe the steps of gametogenesis

A

1) ova/ egg cell forms thru oogenesis
2) sperm forms thru spermatogenesis
3) gametes are derived from PGCs in the 2nd week of fetal development
4) PGCs arrive in the developing gonads of the genetically female or male embryo by 5th week

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20
Q

what is the term for female gamete? male gamete?

A
  • ova/ egg cell
  • sperm
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21
Q

what are PGCs

A

primordial germ cells

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22
Q

describe the overview of mitosis

A
  • primordial germ cells (future mature gametes) first undergo mitosis
  • cell division -> 2 daughter cells that are genetically identical
  • each cell receives the complete complement of 46 chromosomes
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23
Q

describe the overview of meiosis

A
  • future mature gametes then must undergo meiosis to REDUCE CHROMOSOME NUMBER (this process completes at different times in males and females)
  • 2 successive meiotic divisions: meiosis I and meiosis II
  • results in reduction of chromosomes from diploid (46) to haploid (23)
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24
Q

briefly describe meiosis I and meiosis II

A

meiosis I reduces chromosome number to 23
meiosis II resembles mitosis

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25
Q

what is a diploid

A

a cell or organism that has paired chromosomes, one set from each parent -> 2n

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26
Q

what is haploid

A

a cell or organism that has a single set of chromosomes, 1n

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27
Q

what is oogenesis

A

THE PROCESS BY WHICH OOGONIA BECOME MATURE OOCYTES

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28
Q

what happens to cells during oogenesis around the 5th week? at 3 months?

A
  • PCGs undergo mitosis, enter the female gonad @ 5th week, and differentiate to oogonia
  • @ 3 months: some oogonia cells synchronously arrest division in prophase of meiosis 1 ->PRIMARY OOCYTES
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29
Q

when are primary oocytes formed

A

ALL PRIMARY OOCYTES ARE FORMED BEFORE BIRTH

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30
Q

when are oocytes arrested

A

primary oocytes ARRESTED IN PROPHASE 1 REMAIN ARRESTED UNTIL PUBERTY

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31
Q

what is/ are the resulting cell(s) in oogenesis?

A

1 PRIMARY OOCYTE ONLY PRODUCES 1 MATURE GAMETE

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32
Q

what is the overall result if fertilization occurs? what occurs if it does not?

A

1 PRIMARY OOCYTE-> 1 MATURE OOCYTE AND POLAR BODIES
- polar bodies are not fertilized and degenerate
- OVARIAN FOLLICLES are simultaneously undergoing maturation and provide the support for oocyte growth and maturation
- CORPUS LUTEUM secretes hormones to prepare the uterus for pregnancy
- if fertilization doesn’t occur, corpus luteum degenerates to CORPUS ALBICANS

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33
Q

define spermatogenesis

A

process of sperm cell development

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34
Q

what are the steps of spermatogenesis

A
  • PGCs ARRIVE IN THE SPERMATOGONIA, UNDERGO SEVERAL CYCLES OF MITOSIS, AND THEN ENTER MITOTIC ARREST
  • spermatogonia remain dormant until puberty when spermatogenesis begins
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35
Q

describe the haploid/ diploid evolution of spermatogenesis

A

spermatogonia (2n) -> spermatocyte stages (2n -> n) -> spermatids (n) -> mature spermatozoa (n)

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36
Q

how long does spermatogenesis last? describe the 2 significant features

A
  • about 74 days
    1) NO FORMATION OF POLAR BODIES
    2) 1 PRIMARY SPERMATOCYTE -> 4 MATURE SPERMATOZOA
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37
Q

compare oogenesis vs. spermatogenesis

A

oogenesis
- finite pop. of oocytes established by birth
- 1 gamete per meiosis completion
- meiosis begins during fetal period, arrests, and resumes at puberty
spermatogenesis
- continuous stem cell pop.
- 4 gametes per meiosis completion
- meiosis begins at puberty

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38
Q

how many pregnancies end in miscarriage? how many are affected by chromosomal abnormalities? when do they occur?

A
  • 50% of all pregnancies end in miscarriage, usually within 2-3 weeks before woman realizes she is pregnant
    ~ 50% result from chromosomal abnormality, limits birth defects to 2-3% of infants
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39
Q

what two pathways result due to alternate chromosome number? give examples for both categories

A

1) extra chromosomes ex. trisomy 21, Klinefelter syndrome XXY
2) fewer chromosomes ex. monosomy; Turner syndrome XO

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40
Q

what is trisomy 21

A

3 copies of chromosome 21

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41
Q

what is monosomy

A

absence of a chromosome from a pair

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42
Q

what are general features of trisomy 21?

A
  • abnormality due to presence of extra copy of chromosome 21
  • prevalence in the US is 13.65 per 10,000 livebirths
  • karyotype analysis is diagnostic
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43
Q

what are the clinical features of trisomy 21

A
  • varying degrees of intellectual disability
  • craniofacial abnormalities (upward slanting eyes, epicanthal folds, flat facies, small ears)
  • cardiac defect
  • hypotonia
  • INCREASED RISK OF LEUKEMIA, INFECTIONS, thyroid dysfunction, and premature aging
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44
Q

what are the head and neck manifestations of trisomy 21

A

MACROGLOSSIA, GINGIVITIS, PREMATURE PERIODONTITIS

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45
Q

what do certain genetic conditions depend upon?

A

which parent the defective or missing gene arises from

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46
Q

what is the concept of genomic imprinting

A
  • 2 copies of each gene (1 from each parent) are inherited by offspring
  • if a gene from parent 1 IS IMPRINTED, IT IS SILENCED, AND THEREFORE GENE EXPRESSION IN THE OFFSPRING IS ONLY BASED ON PARENT 2
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47
Q

what is an example of genomic imprinting

A

paraganglioma syndrome
- mutations can be inherited from either parent but ONLY paternal transmission conveys disease b/c maternal gene is imprinted

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48
Q

what is the diagnostic tool to identify genetic abnormalities?

A

CYTOGENETIC ANALYSIS
- EXAMINATION OF THE NUMBER OF THE PLOIDY AND THEIR INTEGRITY

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49
Q

what is ploidy? aneuploidy?

A

ploidy: number of sets of chromosomes in a cell
aneuploidy: 1+ extra/ missing chromosomes resulting in an unbalanced chromosome complement
- ex. a cell w/ 49 or 43chromosomes

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50
Q

what is cytogenetic analysis useful for

A
  • looking at chromosomes in detail for prenatal assessment, assessing miscarriage cause, postnatal diagnosis of solid organ malignancies, hematologic malignancies, congenital diseases
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51
Q

what are the 3 specific testing modalities for identifying genetic abnormalities

A

1) FLUORESCENT IN SITU HYBRIDIZATION (FISH)
2) MICROARRAYS
3) EXOME SEQUENCING

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52
Q

describe the FISH specific testing modality

A
  • fluorescent in situ hybridization
  • FLUORESCENT DNA PROBES TO IDENTIFY SPECIFIC CHROMOSOMES OR ABNORMALITIES
  • ex: probe for chromo21 will show 3 copies in a single cell in trisomy 21 (attaches in 3 places)
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53
Q

describe the microarrays specific testing modality

A

small sequences of DNA on chips act as probes to detect mutations

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54
Q

describe the exome sequencing specific testing modality

A

only coding regions of DNA are sequenced and assessed for abnormalities

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55
Q

how does development of a gamete begin?

A

FERTILIZATION - USUALLY OCCURS IN AMPULLA OF FALLOPIAN TUBE
- HAPLOID GAMETES FUSE TO FORM DIPLOID ZYGOTE

56
Q

what cells does the term gametes include

A

sperm and oocyte

57
Q

what makes up an oocyte

A

from female, 22 autosomal chromosomes + 1 sex chromosome (X)

58
Q

what makes up a sperm

A

from male, 22 autosomal chromosomes + 1 sex chromosome (X or Y)

59
Q

what is a genetic male zygote? female zygote?

A

male zygote: XY, Y chromosome carries SRY gene
female zygote: XX, absence of SRY gene

60
Q

what does the SRY gene do? what occurs if it is not present?

A

present: dictates testis differentiation
not present: ovary development

61
Q

how long is the embryonic period

A

0-8 weeks

62
Q

what is the first step of the embryonic period? describe

A
  • zygote undergoes a series of mitotic divisions
    -> starts at 2 cell stage (both cells called blastomeres), moves to 4 cell stage, then becomes morula @ 16 cells at 3 days
  • begins to separate into INNER CELL MASS AND OUTER CELL MASS
63
Q

describe blastocyst formation that occurs during embryonic development. what are the steps before and after this stage

A

-morula travels to uterine cavity, fluid begins to penetrate and forms a single cavity called BLASTOCELE
- EMBRYO AT THIS STAGE IS CALLED THE BLASTOCYST
- blastocyst implants in endometrium along anterior/ posterior wall
-INNER CELL MASS= EMBRYOBLAST, OUTER CELL MASS= TROPHOBLAST
- step before is zygote undergoing mitotic divisions, step after is week of 2s

64
Q

what are properties of the inner cell mass

A
  • source of embryonic stem cells
  • embryonic stem cells are PLURIPOTENT including cells from ALL 3 GERM LAYERS (ECTODERM, MESODERM, ENDODERM)
65
Q

what does pluripotent mean

A

able to give rise to many different cell types

66
Q

what occurs during abnormal implantation? describe

A
  • implantation outside uterus can take place and results in an extrauterine pregn. or ECTOPIC PREGNANCY
  • can occur any place in abdominal cavity, ovary, uterine tube
  • 95% occur in fallopian tube
  • if left to grow can cause adjacent organ damage or life threatening blood loss
67
Q

what happens to maternal immunity while an embryo is forming

A
  • WOMEN IN ORDER TO NOT REJECT THE EMBRYO NEED TO UNDERGO IMMUNE SYSTEM SHIFT, from cell- mediated to humoral (antibody- mediated)
  • not fully understood, but MAY INCREASE MOTHERS’ RISK OF INFECTIONS
68
Q

how can the change in maternal immunity during embryo dev. alter symptoms of a mother’s autoimmune diseases? give examples

A

ex: multiple sclerosis & RA are cell mediated and show improvement during preg.
ex. SLE is predominantly antibody mediated and may worsen during preg.

69
Q

what occurs during the second week of embryo development

A
  • HUMAN CHORIONIC GONADOTROPIC (hCG) hormone is in significant quantities to be detected and are used for PREGNANCY TESTING
  • week of 2s
    -> trophoblast differentiates into 2 layers
    -> embryoblast forms 2 layers
    -> 2 cavities form: amniotic and yolk sac
    -> extraembryonic mesoderm splits into two layers
70
Q

what 2 layers does the trophoblast differentiate into? the embryoblast? what 2 cavities form during week of 2s

A
  • tropho: cytotrophoblast and syncytiotrophoblast
  • embryo: epiblast and hypoblast
  • amniotic and yolk sac cavities
71
Q

what specifically happens during week 1and week 2 of embryo development? what is the overall result?

A

week 1: trophoblast cells invade into uterine wall for implantation
week 2: trophoblast splits into cytotrophoblast (inner) and synctiotrophoblast (outer)
overall: these structures are important to FORMATION OF MUCH OF THE PLACENTA

72
Q

how are body axes established during embryo development

A
  • embryoblast differentiates into epiblast and hypoblast
    -> these cells migrate and orient such that EPIBLAST IS DORSAL AND HYPOBLAST IS VENTRAL
    -> both of these layers together form the BILAMINAR DISC
  • some cells of the hypoblast differentiate into the AVE
    -> AVE CELLS MIGRATE TO FUTURE CRANIAL SITE OF EMBRYO AND ARE IMPORTANT FOR SIGNALING BODY AXES
73
Q

what is AVE

A

anterior visceral endoderm

74
Q

during embryoblast formation what structures do we start to see on the embryo

A
  • AMNIOTIC CAVITY: small cavity appears within epiblast
  • PRIMITVE YOLK SAC: cavity forms between hypoblast and exocoelomic membrane (formed from cells of hypoblast)
75
Q

describe what the yolk sac is and important features

A
  • early pregnancy structure that provides nutrients to growing embryo
  • absorbed by the embryo sometime between 10-14 weeks
  • cells of the yolk sac are important in forming other structures
76
Q

what 3 structures are formed by the cells of the yolk sac

A

1) ORIGIN OF THE FIRST BLOOD CELLS
2) UMBILICAL CORD
3) REPRODUCTIVE STRUCTURES

77
Q

discuss yolk sac tumors

A
  • rarely occur
  • can occur anywhere in the body but most common to ovary or testicle
  • most common malignant germ cell tumor of children
78
Q

what happens when the extraembryonic mesoderm develops? what is it derived from?

A
  • splits into 2 layers: extraembryonic splanchnic mesoderm & extraembryonic somatic mesoderm
  • large cavities form between the layers -> CHORIONIC CAVITY
  • derived from yolk sac cells
79
Q

what is the amnion

A

refers to a membranous structure which covers and protects the embryo (inside chorion)

80
Q

what is the chorion

A

double- layered membrane formed by the trophoblast and extra- embryonic mesoderm, which eventually will give rise to the fetal part of the placenta

81
Q

what characteristic does week 3 of the embryonic have? describe important events during this period

A
  • the trilaminar disc
  • gastrulation is most characteristic event
  • begins in the head region and then moves caudal until end of the 4th week
82
Q

what is gastrulation?

A

THE PROCESS THAT ESTABLISHES ALL THREE GERM LAYERS IN THE EMBRYO
- starts with bilaminar disc (epiblast + hypoblast) -> trilaminar disc
1) ectoderm
2) mesoderm
3) endoderm

83
Q

describe the specifics of gastrulation

A
  • primitive streak appears at the caudal aspect of embryo
    -> cranial aspect of streak thickens and forms primitive node
  • cells of the epiblast begin to invaginate
    -> 1st wave of cells migrating thru the streak interdigitate w/ hypoblast layer -> ENDODERM
    ->2nd wave -> MESODERM
    -> remaining cells in epiblast layer is ECTODERM
84
Q

what do the ecto/meso/endoderm layers give rise to

A

ALL ORGANS AND TISSUES OF THE EMBRYO

85
Q

describe the steps for formation of the notochord and how mouth and anus openings develop

A
  • prenotochordal cells migrate thru the primitive streak, become intercalated in the endoderm to form the notochordal plate
  • plate detaches from endoderm -> NOTOCHORD
  • NOTOCHORD FORMS TH EMIDLINE AXIS WHICH SERVES AS BASIS OF AXIAL SKELETON
  • mouth: oropharyngeal membrane eventually breaks down
  • anus: cloacal membrane breaks down
86
Q

what are key features of weeks 3-8 for the embryonic period

A
  • period of organogenesis
  • by the end main organ systems established
  • THIS TIME AT GREATEST RISK FOR INDUCTION OF BIRTH DEFECTS
    -> SENSITIVE TO GENETIC AND ENVIRONMENTAL IMPACTS
87
Q

what structures are derived from the ectoderm layer

A

1) CNS ( BRAIN & SPINAL CHORD)
2) PERIPHERAL NERVOUS SYSTEM
3) SENSORY EPITHELIUM OF EARS, EYES, AND NOSE
4) EPIDERMIS
5) HAIR AND NAILS
6) SUBCUTANEOUS GLANDS
7) MAMMARY GLANDS
8) PITUITARY GLAND
9) ENAMEL OF THE TEETH

88
Q

what is neurulation?

A

PROCESS BY WHICH THE ECTODERM (GUIDED BY NOTOCHORD) FORMS THE NEURAL PLATE WHICH THEN BENDS UPWARD AND FUSES -> NEURAL TUBE

89
Q

what does neurulation result in?

A
  • segregation of 3 ectodermal derivatives: NEURAL TUBE, NEURAL CREST, AND EPIDERMIS
    -> NEURAL TUBE WILL BECOME THE CRANIAL END AND CAUDAL END (SPINAL CORD)
90
Q

how are neural crest cells formed? where do they go? what are they involved in?

A
  • during formation of neural tube the lateral border/ crest cells dissociate
  • NEURAL CREST CELLS MIGRATE ALL ALONG THE TUBE IN 5 GROUPS THAT FORM SPECIFIC STRUCTURES
    1) cranial
    2) cardiac
    3) vagal
    4) trunk
    5) sacral
  • INVOLVED IN AT LEAST 1/3 OF ALL BIRTH DEFECTS AND MANY CANCERS
91
Q

what structures are derived from the mesoderm layer

A

1) SUPPORTING TISSUES
- MUSCLE
- CARTILAGE
- BONE
- DERMIS OF THE SKIN (CT, NERVES)
2) VASCULAR SYSTEM
- HEART
- ARTERIES
- VEINS
- LYMPH VESSELS, ALL BLOOD AND LYMPH CELLS
3) UROGENITAL SYSTEM
- KIDNEYS
- GONADS
- DUCTS
4) SPLEEN

92
Q

what structures are derived from the endoderm layer

A

1) LINING
- EPITHELIAL LINING OF: GI TRACT, RESPIRATORY TRACT, URINARY BLADDER, URETHRA, TYMPANIC CAVITY, AUDITORY TUBE
2) GASTROINTESTINAL TRACT
3) THYROID
4) PARATHYROID
5) LIVER
6) PANCREAS

93
Q

what is occurring in the ectoderm layer while neurulation is happening

A
  • SIMULTANEOUSLY ENDODERM ROLLS DOWN TO FORM THE GUT TUBE (FUTURE GI TRACT)
  • embryo at this stage consists of a tube on top of a tube
    -> neural tube dorsal
    -> gut tube ventral
94
Q

what is occurring in the mesoderm layer while neurulation is happening

A
  • TWO TUBES ARE HELD TOGETHER BY THE MESODERM
  • mesoderm splits into VISCERAL AND PARIETAL LAYERS
  • between visceral and parietal layers in the primitive body cavity
  • lateral body walls fold ventrally and fuse at midline to create a closed body cavity except in the region connected by the stalk
    -> connecting stalk will become umbilical cord
95
Q

what are the fates of visceral vs. parietal layers? give 3 examples

A
  • visceral layer ultimately covers various organs
  • parietal layer ultimately lines various body cavities
  • between the 2 layers is body cavity space w/ fluid
    ex 1: lungs- visceral and parietal pleura
    ex 2: heart- visceral and parietal pericardium
    ex 3: abdomen- visceral and parietal peritoneum
96
Q

when is the fetal period

A

3rd month -> birth

97
Q

what are important characteristics during the fetal period

A
  • maturation of organ systems
  • rapid growth occurs during this time
    -> length ~ 5 cm/ month for 3rd-5th months
    -> weight: there is a striking increase in last 2 months
98
Q

what are highlights for month 3 of the fetal period

A
  • face becomes more recognizable
  • eyes move from lateral to ventral
  • limbs extend
  • primary ossification centers are present in long bones and skull
  • external genitalia develops to a degree that sex can be determined on ultrasound
99
Q

describe the gut tube

A
  • divided into 3 regions: foregut, midgut, and hindgut
  • midgut communicates w/ yolk sac by way of a broad stalk, the vitelline (yolk sac) duct
    -> gets nutrients to fetus
100
Q

what are highlights for month 4&5 of the fetal period

A
  • fetus lengthens rapidly (end of 5th months weight is still <500g, minimal subcutaneous fat)
  • fetus is covered with fine hair
  • eyebrows and head hair are visible
  • movements are felt by mother by 5th month
101
Q

what are highlights for month 6&7 of the fetal period

A
  • fetus born early in 6th month has difficulty surviving
    -> respiratory system and CNS have not differentiated sufficiently
  • coordination between the systems needed for breathing isn’t well established
  • by 6.5-7 months, fetus has a CRL of ~25cm and weighs ~1100g
    -> BORN AT THIS TIME, THE INFANCT HAS A 90% CHANCE OF SURVIVING
102
Q

what is CRL? CHL?

A

CRL: crown-rump length (sitting height)
CHL: crown-heel length (measurement from vertex of the skull to the heel, standing height)

103
Q

what are highlights for month 8 of the fetal period

A
  • skull has largest circumference of all parts of the body
  • at the time of birth, weight of a normal fetus is 3-3400g
    -CRL is ~36cm and CHL ~50cm
  • most fetuses are born w/in 10-14 days of calculated delivery date
    -> POSTMATURE/ PREMATURE
104
Q

what is the placenta and what are its two components?

A
  • placenta is a fetomaternal organ
  • fetal component (chorion) & maternal component
    -> fetal derived from the trophoblast & extraembryonic mesoderm
    -> maternal derived from uterine endometrium
105
Q

what are the 5 functions of the placenta?

A

1) PROTECTION
2) NUTRITION
3) RESPIRATION
4) EXCRETION
5) HORMONE PRODUCTION

106
Q

what is the amnion? what does it do?

A
  • LARGE SAC CONTAINING AMNIOTIC FLUID IN WHICH THE FETUS IS SUSPENDED BY ITS UMBILICAL CORD
    1) absorbs jolts
    2) allows for fetal movements
    3) prevents adherence of the embryo to the amnion
107
Q

describe amniotic fluid and its key features

A
  • derived primarily from the maternal blood
  • volume is replaced every 3 hours
  • increases throughout pregn. from ~30mL @ 10wks to 1000mL near delivery
  • EITHER HYDRAMNIO OR OLIGOHYDRAMNIOS IS ASSOCIATED W/ BIRTH DEFECTS
  • fetus drinks ~400mL/day beginning at 5 months
108
Q

what does hydramnios mean? what does oligohydramnios mean?

A

hydramnios- too much amniotic fluid
oligohydramnios- too little amniotic fluid

109
Q

what is the difference between dizygotic twins and monozygotic twins

A

dizygotic: fraternal, 2 separately fertilized eggs, NOT GENETICALLY IDENTICAL
monozygotic: identical, 1 fertilized egg splits into 2 embryos, GENETICALLY IDENTICAL

110
Q

what are key features about twins

A
  • di/monozygotic
  • `60% are born preterm (delivery before 37 weeks)
  • high incidence of low birth weight (<2500 g)
  • infant mortality rate is 3x that of single birth
111
Q

what are the 3 causes for birth defect? describe them

A

1) ENVIRONMENTAL FACTORS (15%)
- drugs, pollutants, infectious diseases, maternal diseases
- ex: TORCHES diseases, thalidomide: sedative that caused limb defects
2) GENETIC FACTORS (30%)
- chromosomal abnormalities
- single mutations
3) INTERAXN OF BOTH GEN. AND ENV.

112
Q

what is a teratogen

A

agent/ factor able to induce defects in the embryo

113
Q

what is the susceptibility to a teratogen based on?

A

1) FETAL AND MATERNAL GENETICS
- resistance to infection, drug metabolism
2) DEVELOPMENT STAGE AT THE TIME OF EXPOSURE
- ex: cleft palate can be induced at blastocyst stage/ gastrulation/ 5th week/ 7th week, many induced 3-8 weeks
3) DOSE AND DURATION OF EXPOSURE

114
Q

how does the stage of pregnancy impact pregnancy defects?

A

NO STAGE OF PREGNANCY IS COMPLETELY SAFE FROM TERATOGEN EFFECTS
- more severe if early on

115
Q

list a few teratogens

A

alcohol, androgens, cocaine, lead, tetracycline (causes yellow-gray staining of teeth), tobacco

116
Q

how can we try to prevent birth defects

A
  • supplementation w/ iodine helps eliminate intellectual disability and bone deformities of cretinism
  • women w/ diabetes or phenylketonuria can be under strict dietary regimens
  • folate supplementation: lowers risk of neural tube defects
  • physicians prescribing meds to pregnant women need to be aware of potential teratogenic effects
117
Q

what are the 4 prenatal diagnosis methods? what are the 2 categories and assign each method to the correct category

A

1) ultrasound - screening
2) maternal serum testing- screening
3) amniocentesis- diagnostic
4) chorionic villus sampling- diagnostic
- screening tests and diagnostic tests

118
Q

describe maternal serum testing

A

ex: alpha fetoprotein (AFP)
- normally produced by fetal liver, peaks at 14 wks
- normally increases during second trimester then declines
- abnormally low levels / persistent high levels are seen in various abnormalities like neural tube defects

119
Q

describe amniocentesis

A
  • needle is inserted transabdominally into amniotic cavity and ~20-30mL of fluid withdrawn
  • <14 weeks to ensure enough fluid
  • can perform karyotyping on sample
120
Q

describe chorionic villus sampling

A
  • needle is inserted transabdominally or transvaginally into placental mass and ~ 5-30 of villus tissue withdrawn
121
Q

what occurs in neurulation goes wrong

A

ANENCEPHALY: failure of neural tube to close in the cranial aspect of the embryo
- LETHAL DEFECT THAT CAUSES THE BRAIN TO NOT FORM
SPINA BIFIDA: failure of neural tube to close in the caudal aspect of the embryo
- SEVERITY OF DEFECT RANGES FROM MILD TO SEVERE

122
Q

what are the rates of neural tube defects? how can we lower these

A
  • 1:1500 US births
  • LOWERED BY FOLIC ACID SUPPLEMENTATION BEGINNING ~3 MONTHS prior to pregn
123
Q

what are the 3 types of spina bifida

A

1) SPINA BIFIDA OCCULTA
2) MENINGOCELE
3) MYELOMENINGOCELE

124
Q

describe SPINA BIFIDA OCCULTA. what are the clinical signs

A
  • open posterior vertebral body
    -> usually an incidental finding/ condition found when examining a patient for a separate reason
  • clinical signs: skin change over the bony defect such as a patch of thick hair, growth, unusual pigment, extremely large dimple or pad of fat
125
Q

describe MENINGOCELE

A
  • protrusion of the meninges through opening in the vertebral body
  • sac of fluid comes thru an opening in the baby’s back, spinal cord is not in this sac
  • usually little/ no nerve damage, may cause minor disability
126
Q

describe MYELOMENINGOCELE

A
  • protrusion of spinal cord through opening in the vertebral body
  • spinal cord is damaged
  • causes moderate to severe disability: including paralysis and impaired cognitive function
127
Q

what are neurocristopathies? give a few examples

A

A GROUP OF DISEASES CAUSED BY THE ABNORMAL GENERATION, MIGRATION, OR DIFFERENTIATION OF NEURAL CREST CELLS
ex: DiGeorge syndrome, ectodermal dysplasia, Pierre Robin SEQUENCE

128
Q

what is association

A

a group of malformation that occur together more than would be expected by chance alone

129
Q

what is a syndrom

A

a recognizable pattern of signs/ symptoms that run together. typically differs form association in that a molecular cause has been elucidated

130
Q

what is a sequence

A

a pattern of deformations and malformations which is a consequence of a single malformation
ex: Step 1 causes 2 & 3 to happen

131
Q

describe Pierre Robin Sequence

A
  • well recognized presentation characterized by CLEFT PALATE, MANDIBULAR MICROGNATHIA, AND GLOSSOPTOSIS
  • can occur as an isolated finding or in association w/ other syndromes
  • exact cause is unknown
  • sequence of events: UNDERDEVELOPED JAW -> TONGUE DISPLACEMENT -> CLEFT PALATE or high-vaulted U- shaped palate
132
Q

describe DiGeorge syndrome. what are some clinical features

A
  • caused by 22q11.2 (chromo 22)
    -> most common microdeletion syndrome reported in humans
    -> may be inherited (autosomal dominant) or spontaneous
    -> 1:6000 births
  • multiple associated clinical features: congenital heart disease, breathing abnormalities, CRANIOFACIAL MALFORMATIONS (COMMONLY CLEFT PALATE), IMMUNODEFICIENCY, developmental delay, behavioral and emotional problems
133
Q

describe ectodermal dysplasia

A
  • group of inherited disorders defined by the FAILURE TO DEVELOP 2+ ECTODERMAL DERIVED ANATOMIC STRUCTURES
  • most well- known ectodermal dysplasia (hypohidrotic) syndrome most commonly shows an X-LINKED RECESSIVE INHERITENCE
    -> leads to male predominance of disease
  • clinical features: HYPOPLASTIC OR ABSENT SALIVARY GLANDS, OLIGODONTIA/ HYPODONTIA/ RARELY ANODONTIA, heat intolerance (reduced eccrine glands), fine sparse hair, fine wrinkling and hyperpig. around eyes, midface hypoplasia, dystrophic/ brittle nails
134
Q

what is oligodontia? hypodontia? anodontia?

A

oligo/ hypo: reduced number of teeth
ano: no teeth

135
Q

what is a defect that originates from the mesoderm

A
  • hemangioma
136
Q

what is hemangioma? how does it manifest

A
  • abnormally dense collections of capillary blood vessels that form the MOST COMMON TUMORS OF INFANCY (~10% OF ALL BIRTHS)
  • often associated w/ craniofacial structures
  • tumor may form as a result in defects during vasculature formation

Fundamentals of Patient Management (10 decks)

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