Metabolism vs Digestion
People often get confused when the terms digestion and metabolism come together, such as how do they differ from each other. At the same time, although some people understand these two are different from each other, the exact difference is unknown. Therefore, it would be important to verify what it means by these terms. However, Instead of getting into serious technical terms, it would be best to discuss the characteristics of metabolism and digestion in simple terms. This article reviews what is meant by digestion and metabolism separately and concisely, and then performs a comparison to provide a clear picture for the reader.
Metabolism is an extremely vital set of biochemical reactions taking place, sustaining the life of organisms. Metabolic processes are essential to maintain the growth and development of the organisms, and the extraction of energy through metabolic pathways. Metabolism is mainly composed of two major processes known as catabolism and anabolism, which are responsible for harvest and spend energy. Furthermore, organic matter is broken down through the catabolic processes of digestion and those are burnt via cellular respiration to extract energy. The anabolic processes are conducted using the energy from catabolism to construct vital components viz. proteins and nucleic acids to sustain the life in the organism. The metabolic reactions are well organized as pathways, which are controlled using hormones and enzymes. As the metabolism of different organisms being discovered, it was observed that these metabolic pathways are remarkably similar even in very distinctive species. Ecology and evolutionary biology provide explanations for these remarkable similarities. That means, the potential of metabolic activity determines the sustainability of life of a particular organism.
Digestion is the breaking down of food, which usually contains a series of processes. There are two main types of digestion known as mechanical digestion and chemical digestion. In digestion, simplification of large molecules into small monomers takes place, i.e. it is a catabolic process. Additionally, only the chemical digestion could be regarded as a catabolic process but not the mechanical breakdown. However, there are mainly two forms of digestive systems based on the place of operation; primitive organisms have external digestion, while more evolved advanced animals have internal digestive systems. In advanced animals, digestion starts in mouth, continues through to the stomach and concludes at jejunum. While food passes through oesophagus, the peristaltic movements help to breakdown it into smaller particles. Inside the stomach, the chemical digestion becomes predominant with secretion of digestive enzymes and acids with optimum temperature. Protein digestion starts in the stomach and ends up in the small intestine after converting proteins to amino acids. Lipid digestion starts and ends in the small intestine, which converts lipids into glycerol and fatty acids. Mouth starts carbohydrate digestion and it concludes in the small intestine after forming simple sugars. After all the digestive processes, the nutrients in food are ready for absorption.
What is the difference between Metabolism and Digestion?
• Metabolism involves chemical processes while digestion involves both chemical and mechanical processes.
• Chemical digestion or the enzymatic breakdown of food is a metabolic process. Therefore, chemical digestion falls under the realm of metabolism.
• Metabolism could be either anabolism or catabolism, whereas digestion could be only catabolism.
• Digestion takes place only at the digestive system, whereas all the systems of an organism are incorporated with metabolic activities.
• Digestion is usually taking place in animals only, while metabolism is vital for all the living beings.