What is Digestion?-Definition, Characteristics, and Types

Digestion is the process of breaking down food into its basic components (such as protein, fat, and carbohydrate) and absorbing them into the body. Organs break down food and absorb nutrients into the bloodstream. Includes the mouth, esophageal, stomach, small intestines, large intestines, rectum, anus, liver, gallbladder, pancreas, and spleen.

Need Of Digestion

1. All animals have similar requirements. The animals require water, oxygen, simple sugars, amino acids, fatty acids, vitamins, and many other inorganic and organic substances.

2. Except for water and oxygen, all other substances are rare in the natural environment. So these substances are not available to organisms directly. The substances are available naturally in the form of proteins, starch, fats, vitamins, and minerals.

Nutrition 3. These molecules are useless as such. So they must be broken down or digested into simple molecules like amino acids, sugars, and fatty acids. These simple molecules can easily pass through the cell membranes and are used by the body. Processes occurred during digestion

Characteristic Of Digestion In Animals

Following characteristic processes are involved in the holozoic (animal-like) digestion:

1. Ingestion: The taking in of complex food is called ingestion.

2. Digestion: The breakdown of complex organic compounds of food into simple diffusible molecules by the action of enzymes is called digestion. For example proteins like meat, fish, and egg are broken into amino acids.

 3. Absorption: The uptake of the diffusible food molecules from the digestive cavity into the cells or bloodstream is called absorption.

4. Assimilation: The utilization of the products of digestion for the production of energy or synthesis of cellular material is called assimilation.

5. Egestion: The elimination of undigested matter from the body is called egestion.

Types Of Digestions

There are two types of digestions:

Intracellular Digestion:

The breakdown of food within the cell is called intracellular digestion.

Extracellular Digestion:

The breakdown of food outside the cell within the gut cavity or lumen is called extracellular digestion. In this case; the enzymes for digestion are secreted in the digestive cavity for digestion.