1. Heart
    • 4th week-circulation begins
    • 22 days-heart beat
    • derived from-splanchnic mesoderm, mesenchyme (N.C.), and angioblastic tissue (mesoderm)
  2. Folding the Pericardial Cavity
    • Splanchnic mesoderm
    • -pericardial coelom
    • -cardiogenic cord-becomes heart (mesoderm)
    • Septum transversum-becomes diaphragm
  3. Heart Primordia
    • Splanchinic mesoderm
    • -cardiogenic cord
    • -endocardial heart tube (endocardium)-inside lining of heart
    • Mesenchyme (N.C.)
    • -Myoepicardial mantle (splanchnic mesoderm): includes-
    • ---myocardium-cardiac muscle
    • ---epicardium (visceral pericardium (adult))-outside
    • -Dorsal mesocardium-mesentary-route from n., a., lymph to get to heart and obliterates to form the transverse sinus (space)
  4. cardiac jelly
    connective tissue that stays with the endocardium
  5. Neural Crest Contribution
    • Originate from neural crest in the myelencephalon
    • Migrate through pharyngeal arches 3, 4, and 6
    • Participate in formation of truncus arteriosus (N.C. and mesoderm) and aortiocpulmonary septa (division between aorta and pulmonary trunk)
  6. What occurs if mother takes in high Vitamin A
    Retinoic acid, Hox genes, Nf-1 and Pax 3 regulate cardia neural crest migration and differentiation
  7. Heart Formation
    • Fusion of endocardial heart tubes (mesoderm)
    • Primitive Divisions
    • Folding
  8. Primitive Divisions of Heart
    • Truncus arteriosus
    • Bulbus cordis (together with truncus arteriosus is outflow trap of aorta and pulmonary trunk)
    • Ventricle
    • Atrium
    • Sinus venosus-inflow trap venous system empty into heart-becomes vena cavas
    • *all mesoderm*
  9. Folding of heart
    • Bulbus cordis and ventricles grow quickly
    • heart bends on itself
    • Bulboventricular loop-bends to the right
    • -atrium and sinus venosus come to lie dorsally (in back)
    • -ventricle moves down
  10. Dextrocardia
    • rotation in opposite direction of Bulboventricular loop
    • baby turns out fine if everything switches
    • problem occurs when everything doesn't go same direction
  11. Primitive veins
    • common cardinal-return venous blood from body-enters spinuspinosus (deoxygenated)
    • vitelline-embryonic RBC back to heart (deoxygenated)
    • umbilical-oxygenated from placenta-enters spinuspinosus
  12. Septation: Atrioventricular canal
    • 2 chamber heart to 4 chamber heart
    • Endocardial cushions (mesoderm)
    • -dorsal and ventral walls
    • -mesenchyme invades (N.C.)
    • -cushions grow together
    • right and left canals formed
  13. Septation: Atrium
    • Dorsal atria
    • Shunt blood from right and lefft
    • Septum primum-2 foramen
    • Septum secundum
    • definitive fetal separation of the atria
    • Septum secundum does not completely close, leaving a patent foramen ovale
    • Durign the embryonic and fetal life, blood entering the right atrium passes to the left atrium via the foramen ovale and ostium secundum-form shunt
  14. Septum primum
    • Foramen primum
    • -shunt between right and left atrium
    • -gone when fuses with endocardial chusions
    • Foramen secundum
    • -forms before foramen primum disappears
    • -formation ensures shunting
  15. Septum secundum
    • overlaps septum primum
    • foramen ovale
  16. septation: ventricle
    • interventricular septum: muscular portion (mesoderm)
    • interventricular foramen
  17. Septation: Bulbus cordis and Truncus arteriosus
    • nerual crest cells form ridges (bulbar and truncal)
    • 180 degree spiraling
  18. Aoricopulmonary septum
    • Divides bulbus cordis and truncus arteriosus into ascending aorta and the pulmonary trunk (N.C.)
    • Fuses with the endocardial cushion (mesoderm)
  19. Incorporated bulbus cordis
    • Right: conus arteriosus-ventricles (mesoderm)
    • Left: aortic vestibule (below semilunar valve)-mesoderm
  20. Interventricular Septum
    • attach to muscular portion in foramen
    • membranous interventricular septum
    • -endocardial cushion (mesoderm)
    • -right bulbar ridge (N.C.)
    • -left bulbar ridge (N.C.)
    • complete fusion results in teh disappearance of the interventricular foramen
    • Defects in septum due to membranous part (N.C.) of the septum
Card Set