Holozoic Nutrition: Steps

Holozoic Nutrition: Steps

1.      Ingestion

2.      Digestion

3.      Absorption

4.      Assimilation

5.      Egestion

Ingestion: it is the process of intake of food. Ingestion depends on the size of food and the structure of organ adapted of the ingestion of food. The different organisms have different features to ingest, like amoeba ingest through pseudopodia. Paramecium has cilia, hydra has tentacles, insect use their mouth parts and humans use their mouth.

Digestion: It is the process of breaking down of large sized, complex food that is insoluble and non-diffusible. digestion is a catabolic process. The ingested food is in form of protein, carbohydrates and fats, these are organic polymer compounds. When this food breaks in simpler form, which is soluble and diffusible. The protein converts in amino acids, carbohydrates in form of glucose and fats into fatty acids, these are organic monomer compounds. This breakdown takes place in presence of digestive enzymes that are in digestive juices which are secreted by the digestive glands. Digestion is basically of two types: intracellular digestion and intercellular digestion.  Intracellular digestion takes place inside the cell. This takes place generally in case of lower organisms. Eg; sponges, protozoa, amoeba. .  Intercellular digestion takes place inside the alimentary canal. This takes place generally in case of higher organisms. Eg; human beings

Absorption: it is the process of absorption of diffusible nutrient through the wall of alimentary canal of small intestine. This absorbed food goes in the blood and lymph. Generally the absorption is of two types: physical absorption and active absorption. Physical absorption involves diffusion or osmosis of nutrients whereas active transport involves movement of nutrient through the medium.

Assimilation: it is an anabolic process in which the food that is broken down as simple nutrient gets converted into complex bio molecule inside the cell these polysaccharides helps in the growth and repair of tissue.

Egestion: this is the process of expelling of undigested food in form of faeces. The excess of water, undigested enzymes comprises the faeces. The roughage adds bulk to faeces.