Development of the heart and great vessels Flashcards
where does the heart tube develop from?
lateral plate mesoderm
where do the blood cells and vessels come from?
lateral plate mesoderm
when does the vascular system start developing?
middle of 3rd week of gestation
when does the heart start beating in gestation?
day 22
when does blood begin circulating through the embryo?
day 24 of gestation
cardiovascular abnormalities
make up the largest category of human birth defects
congenital heart defects
33% of babies with chromosomal abnormalities have heart defects
about 2% of heart defects are due to environmental agents
what are the causes of heart defects
multifactorial
complex interplay between genetic and environmental influences
formation of the heart tube
developed from the primary and secondary heart fields
heart fields are derived from the progenitor heart cells in the epiblast
they migrate to the alteral plate mesoderm - cardiogenic region
cells of the heart fields form paired horeshoe-shaped primitive heart tubes within the cardiogenic area
cardiogenic area becomes located at the future thoracic region
paired heart tubes fuse together
structure of developing heart tube
arterial end: aortic sac and roots bulbus cordis - outflow tract truncus arteriosus conus cordis common primitive ventricle common primitive atrium Venous end: sinus venosus
Looping of the heart tube
convergence
occurs at day 23 and is completed by day 28
cephalic portion begins to bend ventrally, caudally and to the right
The caudal end moves dorsocranially and to the left
most of the primitive heart tube becomes drawn into the primitive pericardial cavity
what causes dextrocardia?
abnormality of cardiac looping
formation of atrioventricular canal
primitive common ventricle and atrium connected at a narrow junction. They begin to expand and bulge
