Chapter 6: Developmental Disorders Flashcards
Normal length of human pregnancy and normal newborn weight?
1) 40 +/- 2 weeks
2) 3300 +/- 600 grams
Gestational age of less than 37 weeks
prematurity
1) Appropriate for gestational age (AGA)
OR
2) Small for gestational age (SGA)
Newborn weight <2500g
Low-birth-weight infants
Deficiency of surfactant
Atelectasis
Perfused but not ventilated alveoli = hypoxia & acidosis
Leak of fibrin-rich fluid into the alveoli
Lungs are dark red and airless
Hyaline membranes line the alveolar ducts (eosinophilic, fibrin-rich, amorphous structures)
Within an hour of birth: increased respiratory effort, forceful intercostal retraction and accessory neck muscle use
Respiratory Distress Syndrome of Newborns
Most common acquired gastrointestinal emergency in the neonate
Ischemia of the intestinal mucosa
Injury followed by bacterial colonization (C. difficile)
Lesion: Pseudomembranes to gangrene and perforation of the bowel
RDS of Neonate, necrotizing enterocolitis
Antibody mediated hemolytic disease affecting the fetus in utero
Caused by transplacental passage of maternal antibodies to antigens expressed on fetal RBCs
Rh- mother sensitized to Rh + in first pregnancy, 2nd pregnancy with Rh + baby = DISASTER (increase in mom’s anti-Rh antibody titer)
What type of antibody? Why can it cross the placenta? Disease?
IgG, small enough to cross the placenta (IgM is too large, pentameric) Erythroblastosis fetalis (hemolytic anemia of the neonate)
Absence of an organ coupled with persistence of the organ anlage or a rudiment
For the lung: main bronchus ends blindly in nondescript tissue composed of rudimentary ducts and connective tissue
Aplasia
Pulmonary aplasia
Failure of apposed structures to fuse
Dysraphic anomolies
Reduced size owing to the incomplete development of all or part of an organ
Hypoplasia
Persistence of embryonic or fetal structures that should involute at certain stages of development
Example: persistent thyroglossal duct
Involution failures
Defects caused by incomplete formation of a lumen, these defects were not fully established in embryogenesis
Example: esophagus
Atresia
Brain contains aggregates of normally developed cells arranged into grossly visible “tubers”
Tuberous sclerosis (example of dysplasia)
Focal, benign overgrowths of one or more of the mature cellular elements of a normal tissue, often with one element predominating
Hamartomas
Minute or microscopic aggregates of normal tissue in aberrant locations
Choristomas
Composed of phospholipids, lecithin (phosphatidylcholine, 75%), and phophatidylglycerol (10%)
Concentration of lecithin increases rapidly at the beginning of the 3rd trimester
How can the maturity of the fetal lung be assessed?
Pulmonary surfactant made by type 2 pneumocytes
Measure pulmonary surfactant released into amniotic fluid
Lecithin to sphingomyelin ratio above 2:1 = fetus will survive w/o developing RDS
Most serious form of erthyroblastosis fetalis
Severe edema secondary to congestive heart failure caused by severe anemia
Hydrops fetalis
Severe jaundice + neurological condition
Bile staining of the brain (basal ganglia, pontine nuclei, and dentate nuclei) in the cerebellum
Severe unconjugated hyperbilirubinemia results in injury to brain via interference of mitrochondrial fxn = loss of startle reflex and athetoid movements, lethargy, death or severe mental retardation
Why is there unconjugated bilirubin?
What is the treatment? How does it work?
Kernicterus aka Bilirubin encephalopathy
Bilirubin is unconjugated b/c usually related to erythroblastosis fetalis, immature liver does not have glucuronyl transferase to conjugate released heme, premature infants are more susceptible
Treatment: phototherapy, converts toxic unconjugated bilirubin into isomers that are nontoxic and excreted in the urine
