12-02-11 Heart and Aortic Arches

12-02-11 Heart and Aortic Arches - ZOL320 Developmental...

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ZOL320 Developmental Biology December 2, 2011 Heart and Aortic Arches Heart and circulatory system formation Heart is the 1 st functional organ to form Diffusion of gasses, nutrients, and wastes in cell mass is length (and shape and temperature) dependent Once about 100 um is exceeded, another transport system is needed The circulatory system via the placenta plays roles in gas exchange, nutrition update, and waste excretion. Rate is proportion to size of molecule Factors affecting diffusion: Size of molecule Length of cell mass Constraint on circulatory system vessel formation Physiological o Embryonic circulation : Substitute for organs, not yet functional Evolutionary o Vessel pattern in original 6 aortic arches reflects ancient history Physical o Compromise between ease of blood flow vs. ease of diffusion o Physical constraint = branching Total cross section area of branches is larger than area of original vessels (so no bottleneck occurs)
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12-02-11 Heart and Aortic Arches - ZOL320 Developmental...

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