● The process of taking food into the body is called ingestion . ● The breakdown of complex components of food into simpler substances is called digestion . ● The digested food can now pass into the blood vessels in the wall of the intestine, This process is called absorption . ● The absorbed substances are transported via the blood vessels to different organs of the body where they are used to build complex substances such as the proteins required by the body, This is called assimilation . ● The process of removing undigested waste material from the body by excretion is called egestion .