<prompt> Which of the following makes up the extracellular fluid?Interstitial fluidBlood plasmaBoth of the aboveNone of the above  <response>: In animals with a closed vascular system, the ECF is divided into two components: the interstitial fluid and the circulating blood plasma. The plasma and the cellular elements of the blood, principally red blood cells, fill the vascular system, and together they constitute the total blood volume. The interstitial fluid is that pa of the ECF that is outside the vascular system, bathing the cells. Ref: Ganongs Review of Medical Physiology 23rd edition, Chapter 1. 