<prompt> Which one of the following characterizes a poal system of blood vessels?The absence of a capillary bed, thus shunting aerial blood directly to venulesA capillary bed supplied and drained by a larger, non capillary vesselTwo capillary beds connected by a larger blood vesselA continuous capillary bed that extends from one organ to another  <response>: A poal system of blood circulation is defined as two capillary beds that are joined by an aerial or venous blood vessel. An example is the poal vein connecting the mucosal capillaries of the small intestine to the sinusoids i.e., capillaries of the liver. While capillary beds may connect pas of an organ e.g., adrenal coex, pancreatic islet, capillaries do not extend between organs. Ref: Moon D.A., Foreman K.B., Albeine K.H. 2011. Chapter 10. Midgut and Hindgut. In D.A. Moon, K.B. Foreman, K.H. Albeine Eds, The Big Picture: Gross Anatomy. 