The structures of most federal governments incorporate mechanisms to protect the rights of component states. One method, known as 'intrastate federalism', is to directly represent the governments of component states in federal political institutions. Where a federation has a bicameral legislature the upper house is often used to represent the component states while the lower house represents the people of the nation as a whole. A federal upper house may be based on a special scheme of apportionment, as is the case in the senates of the United States and Australia, where each state is represented by an equal number of senators irrespective of the size of its population.