Meeting Abstract
24.5 Monday, Jan. 5 Structure and Function of theTurtle Heart Through In Vivo Imaging of Blood Flow WYNEKEN, Jeanette; Florida Atlantic University jwyneken@fau.edu
Cardiac structure is quite varied within nonavian sauropsids (reptiles) including shape of the heart, extent of separation of the three intraventricular compartments, degree of development of the intraventricular muscular ridge, and the trabecular network. Species with short or round ventricles tend to have many trabecular ridges compared with those that have elongate ventricles. The structural variations are important in defining major functional differences in reptiles. In species whose hearts lack distinctive intracardiac specializations, how pulmonary and systemic blood flows are maintained by the structure remains as speculation. The hearts of turtles tend to be round, have many densely packed trabeculae, and have less pronounced muscular ridge development when compared with other reptiles. In some suaropsids the muscular ridge is important in separating high O2 vs. low O2 intracardiac flow. The implications of this structural arrangement are that blood flow from the pulmonary and systemic circulation should mix easily in the ventricle. Published physiological studies do not support such a conclusion. In this study, noninvasive imaging was used to trace blood flow in marine turtles. These turtles have relatively large hearts that are relatively easy to view during imaging. To better understand the functional roles of the intracardiac structure in turtles, blood was traced from the sinus venosus to the right atrium and through the interconnected ventricular compartments that are typically viewed as parts of the single pumping system. The results of in vivo functional anatomical imaging suggest that in marine turtles, flow streams from the systemic circulation may be partially maintained structurally by the trabecular networks along with the muscular ridge and also are separated temporally by the intraventricular compartments.
