ch 20 part 1

• where do the heart and circulatory system arise from in vertebrates

  later plate mesoderm
• the lateral plate mesoderm splits into

  dorsal somatic mesoderm and ventral splanchnic mesoderm
• why is circulatory development considered a good example for understanding induction, specification, cell migration etc

  the mechanism for creating the linings of these body cavities from lateral plate mesoderm has changed little throughout vertebrate evolution
• what is the first working unit in the developing embryo, what is the first functional organ

  the circulatory system is the first working unit; the heart is the first functional organ
• movement of cardiac precursor cells in tunicates

  from bilateral cell clusters that migrate anteriorly and ventrally along the endoderm and fuse at the ventral midline
• what do the early heart cells in tunicates have that are also found in mammalian and chick hearts

  the same basic pattern of transcription factors
• which 2 regions does the vertebrate heart arise from

  the splanchnic mesoderm one on each side of the body
• what is a heart field known as 


  cardiogenic mesoderm
• what two regions are the heart fields divided into

  the first field- forms scaffold of developing heart. give rise to the left and right ventricles (major portion of left ventricle)

  second field- give rise to the atria and right ventricle
• all cell types of the heart are generated from what

  the first and second heart fields
• each progenitor cell can become what

  any of the differentiated heart cell types
• what supplements cardiac precursor cells and which heart structures do they specifically contribute to

  cardiac neural crest cells and they contribute to the septum that separates the aorta from the pulmonary trunk
• what prevents heart structures from forming where they shouldn't

  inhibitory signals
• what does the inhibitory signal BMP promote

  heart and blood development
• presense if Fgf8 is crucial for

  cardiac proteins
• what is the role of Wnt proteins in cardiogenic mesoderm specification

  they inhibit heart formation but promote blood formation
• why cardiac and blood forming fields do not form in the center of the embryo

  because the notochord secretes Noggin and Chordin blocking BMP signaling in the center of the embryo
• what is the role of the endoderm in cardiac precursor cell migration

  specifies heart progenitors, gives directionality to their migration and mechanically pulls the two fields together
• what is cardia bifida


  two separate hearts form, one on each side of the body
• what is the phenotype found in zebrafish "miles apart" mutant

  cardia bidida (limited cardiac precursor migration to the midline)
• what is the role of Islet 1

  distinguish between the cells of the second heart field
• what does the anterior region of the SHF contribute to? what does the posterior region of the SHF contribute to?

  contributes to the right ventricle and the outflow tract; the posterior region generates the atria
• what is Tbx5 a marker of


  early heart fields
• what is the function of the retinaldehyde dehydrogenase-2 and what results from the product of this enzyme

  they can produce their own retinoic acid and their posterior fate becomes committed
• what happens as a result of "toxic" exposure to retinoic acid


  causes expansion of atrial tissues at the expense of ventricular tissues
• all the different cell types of the heart are derived from what

  from the same progenitor cell type
• what is a hemangioblast


  rapidly dividing cells, usually stem cells that form blood vessels and blood cells
• what does looping accomplish, what does it change

  converts the original anterior-posterior polarity of the heart tube into the right-left polarity seen in the adult organism. it helps drive looping to completion