Top Ten Powerful Nations 2013 (According to Global Presence). Top Ten Powerful Countries Ranking (2012). NOTE: National Power Index (NPI) 2012 is a comprehensively revised version of the previous National Security Indexes published in Indiaâs National Security Annual Review (INSAR) series since 2002.op Ten Powerful Nations 2013 (According to Global Presence). Top Ten Powerful Countries Ranking (2012). NOTE: National Power Index (NPI) 2012 is a comprehensively revised version of the previous National Security Indexes published in Indiaâs National Security Annual Review (INSAR) series since 2002.
Overview. When you take in food, it's the job of your digestive tract to break that food down into smaller pieces through mechanical digestion, and then break larger molecules into smaller ones through chemical digestion.
1 Partial digestion of the food takes place here. The churning action of the stomach muscles physically breaks down the food.  The stomach releases acids and enzymes for the chemical breakdown of food. The enzyme pepsin is responsible for protein breakdown.