Provide definitions/explanations for the following terms:
$(1)$ Digestion
$(2)$ Peristalsis

(N/A) $(1)$ The process of converting complex food components into simple and absorbable forms with the help of enzymes is called digestion.
$(2)$ The rhythmic contraction and relaxation of the muscular walls of the digestive tract that pushes food forward,particularly in the oesophagus,is called peristalsis.