Meeting Abstract

74.6  Monday, Jan. 6 09:15  Simulations of heart-beat reversal in sessile tunicates WALDROP, LD*; MILLER, LA; Univ. of North Carolina, Chapel Hill; Univ. of North Carolina, Chapel Hill lwaldrop@email.unc.edu

Sessile tunicates (Chordata: Urochordata) possess an open circulatory system with a few major vessels and a tubular heart that drives blood flow through interconnected sinuses. The heart pumps blood by a peristalsis-like mechanism, in which a wave of muscular contraction travels down the tube from one end to the other. Every few minutes, the heart stops these contractions and after a brief pause, the contractions restart in the opposite direction which forces a reversal in the direction of blood flow. Several reasons for this reversal have been suggested, including heart-beat reversal serves to more efficiently transport nutrients and waste in an open system with porous components than unidirectional flow. We test this hypothesis by using the immersed boundary method to simulate flow created by the tubular heart in a racetrack circulatory system with a porous component representing the open nature of the system. Transport efficiency for periodic, bidirectional flow created by heart-beat reversal and unidirectional flow are compared.