n a committee set up to prepare and arrange topics to be discussed, the order of business, etc., for a legislative assembly or other body. vigilance committee. n (in the U.S.) a self-appointed body of citizens organized to maintain order, punish crime, etc., where an efficient system of courts does not exist.
Best Answer: Annelids have closed circulatory systems, which means that blood is always contained by blood vessels. Some mollusks and arthropods, on the other hand, have open circulatory systems, which means that at some time, blood from the heart will pump into the hemocoel or blood cavity.n Annelids, the blood vessels end up with capillaries. Hence called closed BVS. In cockroach it is open BVS as blood vessels don't end up with capillaries. Hence, the blood vessels bluntly open into body cavities. NOTE: Circulatory system is also called BVS.
The blood vessels are part of the circulatory system and function to transport blood throughout the body. The most important types, arteries and veins, carry blood away from or towards the heart, respectively. All blood vessels have the same basic structure. The inner lining is the endothelium and is surrounded by subendothelial connective tissue. Around this there is a layer of vascular smooth muscle, which is highly developed in arteries. Finally, there is a further layer of connective tissue known as the adventitia, which contains nerves that supply the muscular layer, as well as nutrient capillaries in the larger blood vessels.