Define assimilation, absorption in terms of the human physiological process

Absorption: This is the process where digested food molecules (like glucose, amino acids, fatty acids, and glycerol) pass from the digestive tract (primarily the small intestine) into the bloodstream or lymphatic system. These molecules cross the intestinal lining to enter the body's internal environment.

Assimilation: This is the process where the absorbed food molecules are transported to the body's cells and tissues, where they are then taken up and used for various metabolic activities. This includes using glucose for energy, amino acids for protein synthesis, and fatty acids for building cell membranes or storing energy.