Question

How is digestion a series of chemical reactions?

Answer 1

Digestion is a type of catabolism that, depending on the way food is broken down, is often divided into two processes: mechanical and chemical digestion. The term mechanical digestion refers to the actual breakup into smaller bits of large pieces of food which can be reached by digestive enzymes afterwards.

Complete answer:
Digestion is a continual phase of chemical reactions and procedures up to the final recycling of water and waste disposal, from the mechanical degradation by chewing and the application of saliva enzymes to the beginning of the chemical transformation of foods.
In order to break down cellular membranes in food, the stomach requires hydrochloric acid, which then goes into the small intestine for further enzyme decomposition. The valuable compounds - proteins, carbohydrates and vitamins - are mainly derived from the small intestine. When re-adsorbing as much moisture from the diet and related fluid as possible, the large intestine absorbs additional nutrients.

Trichonympha zooflagellate is a cellulose-digesting insect-gut. For locomotion, it requires flagella. In the gut of termites, this zooflagellate occurs as a symbiont. Trichonympha secretes beta-glucosidases, a cellulose-digesting enzyme that transforms cellulose into glucose. Zooflagellates and termites share the digested food. The termites starve and die without Trichonympha.

Note: Starch can be digested in the gastrointestinal tract to provide the body with nutrition, but native starch is not readily digested in the human body without processing (such as cooking) because of its semi-crystalline form, which usually delays digestion.