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52 Cards in this Set
- Front
- Back
Where is Sonic Hedgehog Gene produced and what is its function?
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SHH:
- produced @ BASE of limbs (in the ZPA) - Involves A-P Axis patterning (anterior-posterior) - Mediated ECTOdermal fx |
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A mutation of what gene leads to holoprosencephaly?
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Defect in sonic hedgehog (SHH).
Holoprosenchephaly = Failure to develop 2 hemispheres in brain |
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What is the function of WNT-7 gene?
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- Produced at the DISTAL end of developing limbs
(Apical Ectodermal Ridge) - Necessary for D-V Axis organization (dorsal-ventral) |
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What is the FGF Gene and what is its function?
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FGF = Fibroblast Growth Factor
- produced at Apical Ectodermal Ridge - Stimulates mitosis of MESODERM - Results in lengthening of limbs |
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What embryological gene is associated with Achondroplasia?
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Mutation in the FGF Gene
(fibroblast growth factor) |
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What is the Hox gene & what is its function? What teratogen can interfere with it?
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Hox = Homeobox Gene
- involved in SEGMENTAL organization (cranio-caudal direction) - is the blueprint for skeletal morphology (mutations = appendages in wrong location) Teratogen = Retinoic acid (Vit A) |
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What gene mutation results in Synpolydactyly?
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Mutation of HOX-D13
Synpolydactyly = extra fused digit b/w the 3rd and 4th digits |
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Stages and timing from fertilization --> implantation of a pregnancy?
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Day 2 = Zygote (in tube)
Day 3 = Morula Day 5 = Blastocyst Day 6 = Implantation Implantation --> release of ßhCG |
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What is the primitive streak?
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First asymmetry in embryogenesis:
- Formed in the 3rd week - Epiblast invaginates to form. - Creates antero-posterior axis This marks beginning of gastrulation. Cells of primitive streak give rise to: - Mesoderm - Endoderm |
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What embryological developments have taken place by week 2?
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Rule of 2's:
- 2 Germ cell layers 1) epiblast 2) hypoblast - 2 Cavities: 1) amniotic cavity 2) yolk sac - 2 Placental components 1) cytotrophoblast 2) syncytiotrophoblast |
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What embryological developments have taken place by week 3?
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Rule of 3's:
- 3 Germ layers: 1) ectoderm 2) mesoderm 3) endoderm (these are the Tri-Laminar Disc) This is now the Gastrula. Also: - primitive streak has formed - notochord & neural plate |
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What is the bilaminar disc?
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This is the 2 germ layers that are present by week 2 of embryogenesis.
Includes: - Epiblast - Hypoblast |
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What is the trilaminar disc?
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This is the 3 germ layers that make up the Gastrula in week 3 of development:
- Ectoderm - Mesoderm - Endoderm |
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What are the early stages of neural development?
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1) Notochord induces ectoderm --> neuroectoderm --> neural plate
2) Neural plate --> invaginates forming Neural crest 3) Neural Crest --> Neural tube & Neural crest cells |
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What happens to the notochord?
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After stimulating ecotderm --> neuroectoderm, it becomes the nucleus pulposus of the intervertebral disk in adults
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What are the landmarks of week 4 of embryological development?
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Rule of 4:
- 4 heart chambers (begins to beat) - 4 limb buds formed Also, the neural tube has closed by week 4 (problems e.g. spina bifida has occured by this point) |
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Why is folic acid important to pregnant women immediately when they conceive?
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Folic acid is necessary for neural tube development, most of which is completed by week 4 of development.
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What is the embryonic period?
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Weeks 3-8 of development
- Organogenesis takes place. - Extemely susceptible to teratogens |
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When does the fetal period begin?
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Week 8 of development.
There is fetal movement and fetus looks like a baby |
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By what time does the fetus have male/female genital characteristics?
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Week 10 of development
(12 Weeks since LMP) |
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What are the embryologic derivatives of the Surface ectoderm?
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1) Adenohypophysis (anterior pituitary)
2) Lens (anterior of eye) 3) Epithelia: - oral cavity - olfactory - anal canal (below pectinate) - epidermis 4) Sensory organs of ear 5) Glands: - sweat - salivary - mammary |
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What is a craniopharyngioma and from what does it develop?
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A benign tumor from Rathke's pouch (surface ectoderm).
Seen with: - cholesterol crystals - calcifications |
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What are the embryological derivatives of Neuroectoderm?
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Think CNS and Brain:
1) Brain - CNS neurons - neurohypophysis (posterior pituitary) - pineal gland - ependymal cells (line ventricles) - glia (astrocytes, oligodendrocytes) 2) Retina (posterior eye) 3) Spinal Cord |
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What are the embyrological derivatives of the Neural Crest?
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CACA MOTEL PASS:
C = Cranial Nerves A = ANS - chain ganglia C = Craniofacial structures (skull) A = Arachnoid, pia M = Melanocytes O = Odontoblasts T = Tracheal cartilage E = Enterochromaffin cells - Adrenal medulla L = Laryngeal cartilage P - Parafollicular cells (C cells) - of thyroid A = All ganglia - Dorsal root, Celiac, CN, ANS Chain S = Schwann cells S = Spiral septum - Aorticopulmonary septum (think the PNS and non-neural surrounding structures) |
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What are the embryological derivatives of Endoderm?
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1) Gut tube epithelium (above pectinate line)
2) Derivatives (2L, 2P, 2T): - Lung - Liver - Pancreas - Para-Thyroid - Thymus - Thyroid (follicular cells) |
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What are the embryological derivatives of Mesoderm?
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1) Muscle, bone, CT
2) Linings (e.g. peritoneum) 3) Spleen 4) Circulation (CV, Blood, Lymphatics) 5) Uro-Genital & Gonads 6) Dermis (skin) 7) Notochord --> nucleus pulposus of intervertebral disk |
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Birth defects related to Mesoderm?
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VACTERL Defects:
V = Vertebral defects A = Anal atresia C = Cardiac defects T-E = Tracheo-Esophageal Fistula R = Renal defects L = Limb defects (muscle/bone) |
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Classic characteristics of Fetal Alcohol Syndrome?
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1) Facial Abnormalities:
- nose = flat - philtrum = smooth - ears = low set ("railroad track") - eyes = epicanthal folds 2) Retardation 3) Limb dislocation 4) Fistulas (heart and lung) 5) Cranial development (microcephaly, holoprosencephaly) |
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When is developing baby most susceptible to teratogens?
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Embryonic period (3-8 weeks)
Time of organogenesis. - before week 3 = all or nothing - after week 8 = growth & fx |
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What is the teratogenic effect of ACE Inhibitors?
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Renal damage
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What is the teratogenic effect of alkylating agents?
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Absent digits.
Multiple anomalies. Are used in chemo to stop cell growth. |
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What is the teratogenic effect of Aminoglycosides?
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CN VIII toxicity (hearing defects)
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What is the teratogenic effect of Carbamezepine?
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Neural tube defects (inhibit maternal folate absorption ~ like valproate)
Also: - Craniofacial defects - Fingernail hypoplasia - Developmental delay - IUGR |
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What is the teratogenic effect of Diethylstilbestrol (DES)?
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Mullerian abnormalities (fallopian tubes, uterus, cervix, vagina)
Also increased vaginal clear cell adenocarcinoma risk. Affects the "DES Daughters" |
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What is the teratogenic effect of Tetracyclines?
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Discolored teeth
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What is the teratogenic effect of Thalidomide?
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Phocomelia = Limb defects
("flipper" limbs) |
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What is the teratogenic effect of Warfarin?
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Bone deformities
Fetal hemorrhage Ophthalmic abnormalities Abortion (use Heparin instead b/c it doesn't cross placenta) |
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What is the teratogenic effect of DM?
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Caudal regression syndrome
Heart defects (transposition of great vessels) Neural tube defects Macrosomia |
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What is the teratogenic effect of Retinoic Acid?
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Spontaneous abortions
Many birth defects d/t interference w/ HOX Gene |
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What are the fetal components of the placenta and what do they do?
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1) Cytotrophoblast = INNER layer of chorionic villi that makes cells
2) Syncytiotrophoblast = OUTER layer of chorionic villi that makes hCG (stimulates corpus luteum to continue to secrete PROG) |
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What is the maternal component of the placenta and where does it develop from?
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The Decidua basalis.
It is derived from endometrium. |
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What are the vessels in the umbilical cord?
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- 2 x Umbilical arteries = return DE-OXYGENATED blood from the fetal internal iliacs
- 1 x Umbilical Vein = brings OXYGENATED blood to fetus, draining into the fetal IVC NOTE: umbilical vessels are derived from the allantois |
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What is the most common congenital abnormality?
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Single umbilical artery.
Usually inconsequential, however commonly associated w/ renal problems; also associated w/ other congenital and chromosomal abnormalities. |
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What problems occur if the urachal duct fails to close?
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Should obliterate in 3rd week.
1) Patent urachus = urine discharged from umbilicus 2) Vesicourachal diverticulum = outpouched bladder |
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What problems occur if vitelline duct fails to close?
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Should obliterate in 7th week.
1) Vitelline fistula = meconium discharged from umbilicus 2) Meckel's diverticulum = partial closure |
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What is Meckel's diverticulum, what is its cause, and what are some symptoms?
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Incomplete closure of vitelline duct leads to diverticulum @ the ileum.
Syx = periumbilical pain and melena (can be d/t ectopic gastric mucosa) |
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What are congenital anomalies associated with the Truncus arteriosus?
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Gives rise to ascending aorta & pulmonary trunk; neural crest cells --> aorticopulmonary septum
1) Transpotition of great vessels (failure to spiral) 2) Tetralogy of Fallot (skewed AP septum) 3) Persistant truncus arteriosus (partial AP septum) |
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Where does fetal erythropoeisis occur?
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"Young Liver Synthesizes Blood"
Y = Yolk Sac (up to 8 weeks) L = Liver (8-28 weeks) S = Spleen (8-28 weeks) B = Bone Marrow (28 weeks +) |
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Difference b/w fetal and adult hemoglobin?
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Fetal has 2 gamma chains
Adult has 2 beta chains Gamma has higher O2 affinity / lower 2,3-DPG affinity Results in O2 shunt from mom --> infant |
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Why does the foramen ovale close?
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Infant's first breaths cause:
1) decrease pulmonary pressure 2) increase (relative) LA pressure (vs RA pressure) Foramen ovale --> Fossa ovalis |
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What causes closure of the ductus arteriosus?
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Increase in O2 --> decrease in PG's
Rx = Indomethacin (helps close PDA) PG's will keep PDA open |
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What drug can help close a PDA?
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Indomethacin.
PG's will keep a PDA open. |