Introduction. Beta-blockers, also known as beta-adrenoceptor blocking agents, are medications used to treat conditions such as angina, heart failure and high blood pressure. They decrease the activity of the heart by blocking the action of hormones like adrenaline.
1 The concept of âdemographic changeâ describes a populationâs age structure adjusting to. changes in living conditions. Consequently, changes in thcomposition of a societyâe s age. structure are the result of social shifts. (. 2  cf. . 3  theory of first and second demographic transition.
United States Population (1950 - 2017) Yearly Population Growth Rate (%) The current population of the United States of America is 326,002,603 as of Thursday, April 20, 2017, based on the latest United Nations estimates. the United States population is equivalent to 4.34% of the total world population. the U.S.A. ranks number 3 in the list of countries (and dependencies) by population.