What is the Difference Between Digestion and Assimilation

Digestion and assimilation are two processes associated with the digestive system. In fact, they are key processes in the body that involve the breakdown and use of nutrients. However, there is a distinct difference between digestion and assimilation.

What is the difference between digestion and assimilation? Digestion is the breakdown of food into smaller parts that can be absorbed by the body, whereas assimilation is the process by which absorbed nutrients are used up by the body for energy, repair, and growth.

Key Areas Covered

1. What is Digestion 
      – Definition, Features
2. What is Assimilation
      – Definition, Features
3. Similarities Between Digestion and Assimilation
      – Outline of Common Features
4. Difference Between Digestion and Assimilation
      – Comparison of Key Differences
5. FAQ: Digestion and Assimilation
      – Answers to Frequently Asked Questions

Key Terms

Assimilation, Digestion 

What is Digestion 

Digestion is a process by which food is broken down into smaller parts that can be absorbed by the body. The digestive system performs the digestion of food. Parts belonging to the digestive system include the mouth, buccal cavity, pharynx, oesophagus, stomach, pancreas, duodenum, gallbladder, small intestine, large intestine, rectum, and anus.

Intake of food happens through the mouth. Chewing breaks down food into smaller pieces, and we call this mechanical digestion. Chemical digestion (saliva) breaks downcarbohydrates into smaller parts with the help of enzymes. Then the food bolus travels through the oesophagus by peristaltic movements into the muscular stomach.

Here, powerful contractions churn and mix the food with even more digestive juices, including stomach acid, to further break down complex molecules, especially proteins.

After the activity in the stomach, the partially digested food enters the small intestine. Here, enzymes from the pancreas and bile play significant roles. Bile emulsifies fat, breaking it into smaller droplets. Enzymes break down carbohydrates, proteins, and fats, converting them into their simplest forms, which are sugars, amino acids, and fatty acids. These tiny compounds pass through the small intestine wall and are absorbed into the body. The remaining indigestible material moves to the large intestine, where the absorption of water takes place. As the final step, waste products are eliminated from the digestive system as stool.

What is Assimilation

Assimilation is the process by which absorbed nutrients are used by the body for energy, repair, and growth. It follows digestion, which breaks down food into its simplest parts. Assimilation takes those components and incorporates them into the body’s systems.

The small intestine plays a major role in assimilation by absorbing amino acids, sugars, and fatty acids. These nutrients then enter the bloodstream and are delivered throughout the body. The liver acts as a processing center, sorting usable nutrients and filtering out waste. Once sorted, these nutrients can be utilized: sugars like glucose become fuel for our cells, keeping us energized, while amino acids—the building blocks of proteins—are incorporated into muscles, tissues, and even hormones. Not only these, but vitamins and minerals are also absorbed by the body and delivered to the areas where they are used.

Similarities Between Digestion and Assimilation

1. Digestion and assimilation involve food processing.
2. Moreover, both occur within the digestive system.

Difference Between Digestion and Assimilation

Definition

• Digestion is the breakdown of food into smaller parts that can be absorbed by the body, whereas assimilation is the process by which absorbed nutrients are used up by the body for energy, repair, and growth.

Order

• Digestion comes first, breaking down complex food molecules into simpler forms. Assimilation follows, taking these simpler components and incorporating them into the body.

Organs Involved

• Digestion occurs mainly in the mouth, stomach, and small intestine. Conversely, assimilation primarily happens within the cells throughout the body, although the small intestine plays a vital role in nutrient absorption.

Involves

• Digestion is a mechanical and chemical breakdown process. Teeth grind food, enzymes break down complex molecules, and stomach acid further breaks down components. Assimilation involves absorption and utilization. Nutrients are absorbed into the bloodstream and then taken up by cells for various purposes.

Conclusion

In conclusion, digestion and assimilation are integral processes in the human body’s utilization of nutrients. Digestion breaks down food into smaller, absorbable components, primarily occurring in the mouth, stomach, and small intestine. Assimilation, on the other hand, involves the absorption of these nutrients into the bloodstream and their incorporation into various bodily systems for energy, repair, and growth. Therefore, the difference between digestion and assimilation is their role.

FAQ: Digestion and Assimilation

1. What is the difference between digestion and absorption?

The main difference between digestion and absorption is their role. Digestion is the process by which food is broken down into smaller parts, whereas absorption is the process of taking the products of digestion across the gastrointestinal tract and into circulation.

2. What is the difference between ingestion and assimilation?

Ingestion is the process of taking food into the body. Assimilation, on the other hand, is the process in which the absorbed food is taken in by body cells and used for energy, growth, and repair.

3. Is swallowing ingestion or digestion?

Swallowing is ingestion. Ingestion is the act of taking in food and drink through the mouth. This includes the initial stages of eating such as chewing and swallowing. Swallowing helps to move food from the mouth to the esophagus and is a necessary step before digestion can begin in the stomach and small intestine.

4. What comes first, ingestion or digestion?

Ingestion comes first. Ingestion is the process of taking food into the body, whereas digestion is the process by which food is broken down into smaller parts in the stomach.

5. What is an example of assimilation in the human body?

Assimilation is the process of taking absorbed nutrients and incorporating them into the body’s systems. For example, glucose, which is absorbed from digested food, is used in cellular respiration to produce energy for the body. Amino acids, which are the building blocks of proteins, are used to synthesize new proteins for muscle growth, tissue repair, and hormone production.

Reference:

1. “Assimilation (biology).” Simple Wikipedia.  
2. “Digestion.” Wikipedia. Wikipedia Foundation.

Image Courtesy:

1. “2405 Digestive Process” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia