The Cardiovascular system consists of the Heart, Arteries and Veins. The heart is the pump which drives the blood and the arteries and the veins are vessels which carry the blood around the body. The...
Medieval feudal system:King is the most important person and rules all of the lands, then it goes to nobles which rule the lands FOR the king. Knights protects the land, and peasants farm the land.
This is the body's ventilation system. The respiratory system brings oxygen into the lungs and eliminates carbon dioxide. Each cell in our body needs oxygen. The process of supplying the cells with...