Infection with filarial worms causing elephantiasis. Block lymph vessels so that interlular fluid can not drain and protein builds up in this fluid. Starvation causing fluid accumulation in the belly. It closes when the oppoisite is true. Since it is responding to the intercellular fluid it controls the flow of this fluid in a nice negative feed-back system.
Muscle circles the vessel at beginning of capillary.
Describe the adaptions that diving animals use to prolong their stays under water.