The process of digestion is referred as mechanical and chemical breakdown of the ingested food into smaller form which can be readily and rapidly absorbed into the blood stream. The process is mainly referred as catabolism with the utilization of energy. It is also referred digestive tract and alimentary canal based on the physiological and anatomical significance.
In humans (most evolved species on earth) the digestive tract is around 5 meters – 9 meters and is composed of upper and lower digestive tract. The digestive tract is further categorized as foregut, midgut, and hindgut which speak of the embryological origin of each part.
Digestion is the process of breaking down of complex food molecules into simpler food molecules to make them absorb-able by living membranes.
The path of food through the alimentary canal is as follows:-
Mouth → Food pipe or esophagus → stomach → small intestine → large intestine → excreted
The above path can be divided into three parts:-
Digestion: complex molecules of food are broken down to simpler ones by the saliva, gastric juice, bile and pancreatic juice.
Absorption: Essential and needed components of the food are absorbed from it in the small intestine
Excretion: The waste food not containing nutrients is excreted away.
Components of Digestive System
In view of the diverse metabolic requirement of human body the digestive system is at its highest anatomical order. The flow of the food from mouth to the intestine in a proper and systematic manner is due to the proper arrangement of components in digestive system.
The digestive system is split as Upper and Lower gastrointestinal tract to understand in a better way. The upper gastrointestinal tract is composed of mouth cavity, pharynx, esophagus, stomach, and duodenum. The lower digestive tract is mainly with intestine and anus.
The lower digestive system composed of intestine is the key component in the alimentary canal and is responsible for assimilation and absorption of the food that is digested in stomach. It is also responsible for secretion of intestinal juices which are poured into stomach to enhance the digestion.
It includes the following
Small Intestine: Includes 3 parts such as Duodenum, jejunum and ileum.
Large Intestine: Also includes 3 parts: Cecum, Colon, and Rectum.
Digestive System :evolutionary Significance
In terms of evolution human digestive system stands high based on the involvement of highly developed anatomical organs as mentioned above. The human digestive system also signified the embryological development which also makes the human being as highly evolved animal on earth.
In entire animal kingdom digestive tract has a special place as it includes 4 specific organs which are under specialized category
1) Tongue: Present only in chordates.
2) Esophagus: In case of birds, insects and invertebrates it is the place of storage
3) Stomach: Birds have muscular architecture called ventriculus.
