The muscular system. The muscular system is composed of specialized cells called muscle fibers. Their predominant function is contractibility. Muscles, attached to bones or internal organs and blood vessels, are responsible for movement. Nearly all movement in the body is the result of muscle contraction. Exceptions to this are the action of cilia, the flagellum on sperm cells, and amoeboid movement of some white blood cells. The muscular system in vertebrates consists of three different types of muscles: cardiac, skeletal and smooth.
Welfare Statistics by Race, State and Payment. There are approximately 12.8 million Americans on welfare, accounting for 4.1% of the US population. An estimated $131.9 billion is spent by the government on welfare each year. The following percentages are recipients of welfare based on race. â¢ White â 38.8%.
U.S. Cities are Home to 62.7 Percent of the U.S. Population, but Comprise Just 3.5 Percent of Land Area. A majority of the U.S. population lives in incorporated places or cities, although these areas only make up a small fraction of the U.S. land area, according to a new report released today by the U.S. Census Bureau. The percentage of the population living in cities in 2013 was highest in the Midwest and West at 71.2 percent and 76.4 percent, respectively.