PROCESS OF DIGESTION

Ingestion

is the entry of food into the alimentary canal through the mouth. There, the food is chewed and mixed with saliva, which contains enzymes that begins breaking down the carbohydrates in the food plus some lipid digestion via lingual lipase.

Propulsion

refers to the movement of food through the digestive tract. The act of swallowing is when the tongue and pharyngeal muscles propel it into the esophagus, the last voluntary act until defecation. It includes both the voluntary process of swallowing and the involuntary process of peristalsis. Peristalsis consists of sequential, alternating waves of contraction and relaxation of alimentary wall smooth muscles, which act to propel food along. Peristalsis is so powerful that foods and liquids you swallow enter your stomach even if you are standing on your head.

Mechanical digestion

is a purely physical process that does not change the chemical nature of the food. it makes the food smaller to increase both surface area and mobility

mastication

or chewing, as well as tongue movements that help break food into smaller bits and mix food with saliva. Although there may be a tendency to think that mechanical digestion is limited to the first steps of the digestive process, it occurs after the food leaves the mouth, as well.

Churning

is contracting and relaxing of stomach, serves to further break it apart and expose more of its surface area to digestive juices, creating an acidic “soup” called chyme.

Segmentation

which occurs mainly in the small intestine, consists of localized contractions of circular muscle of the muscularis layer of the alimentary canal.

Chemical digestion

it’s the breakdown of nutrients such as starches into sugar, fats into fatty acids and proteins into amino acids. The process occurs in the mouth, stomach, and small intestine. Food that has been broken down is of no value to the body unless it enters the bloodstream and its nutrients to be absorbed. Many cells in this system are specialized, like taste buds which sense chemicals in our mouth, parietal cells that secrete acid into our stomach, and enterocytes which absorb water and nutrients.

Absorption

is when the product of digestion is absorbed by the blood through the bloodstream to be supplied in the body. Simple diffusion is defined as the process in which a substance moves through a semipermeable membrane or in a solution without any help from transport proteins.

Defecation

is the final step in digestion, undigested materials are removed from the body as feces