Define the following terms:
$(1)$ Absorption
$(2)$ Assimilation

(N/A) $(1)$ Absorption: The process by which the end products of digestion,such as glucose,amino acids,fatty acids,and glycerol,pass through the intestinal mucosa into the blood or lymph is called absorption.
$(2)$ Assimilation: The process by which the absorbed food substances are utilized by the body cells for various activities,such as the synthesis of proteins,lipids,and carbohydrates,is called assimilation.