Difference Between Mechanical Digestion and Chemical Digestion

Main Difference

The main difference between mechanical digestion and chemical digestion is that mechanical digestion is the mechanical breakdown of large food particles into small food particles, whereas chemical digestion is the chemical breakdown of high molecular weight substances into low molecular weight substances.

Mechanical Digestion vs. Chemical Digestion

Mechanical digestion generally refers to the breakdown of food mainly by teeth into digestible particles, whereas chemical digestion generally refers to the process by which high molecular weight substances in the food are broken down into small substances with a low molecular weight that can be absorbed by the body.

Mechanical digestion mainly occurs from mouth to the stomach while chemical digestion normally occurs from mouth to the intestine. In mechanical digestion, a major portion of this digestion occurs in the mouth; on the other hand, in chemical digestion, a major part of digestion occurs in the stomach.

Mechanical digestion is driven by teethes; on the contrary, various enzymes are responsible for driving chemical digestion. Mechanical digestion is the physical breakdown of food by chewing, whereas chemical digestion is the mixing of food with saliva.

In mechanical digestion, breakdown of large food particles into small food particles occurs; on the flip side, in chemical digestion, the chemical breakdown of high molecular weight substances into low molecular weight substances occur.

Mechanical digestion usually increases the surface area for the enzymatic actions to occur in chemical digestion; conversely, chemical digestion mainly boosts the absorption of nutrients by breaking down them down into small substances.

Comparison Chart

Mechanical DigestionChemical Digestion
The physical breakdown of food pieces into smaller ones, which can subsequently be accessed by digestive enzymes is the mechanical digestion.The process in which enzymes breakdown food into small molecules that the body can use is the chemical digestion.
Occurrence
From mouth to the stomachFrom mouth to the intestine
Major Part
A major portion of digestion occurs in the mouthA major part of digestion occurs in the stomach
Driven By
Driven by teethesDriven by enzymes
Mechanism
Breakdown of large food particles into small food particles occurThe chemical breakdown of high molecular weight substances into low molecular weight substances occur
Role
Usually increases the surface area for the enzymatic actions to occur in chemical digestionMainly boosts the absorption of nutrients by breaking down them down into small substances
Process/Method
The physical breakdown of food by chewingThe mixing of food with saliva

What is Mechanical Digestion?

The mechanical digestion is the physical breakdown of large food pieces into smaller ones, which can subsequently be gain access by digestive enzymes. This term means that the ingested large food particles are broken down into smaller ones by the act of chewing mainly in the mouth, churning in the stomach, and then segmentation of particles in the small intestine.

The initial breakdown of food occurs in the mouth by the grinding actions of teethes. This process is also called mastication or chewing. The next step involves the tongue which pushes the mechanically digested food into the throat as a bolus. These boli pass through the esophagus to the stomach.

The mechanism by which the food moves through the esophagus is peristalsis. In peristalsis, the rhythmic contractions and relaxation of the section of the longitudinal smooth muscles in the walls of esophagus allowing the unidirectional movement of food through the alimentary canal. By the muscular movements of the stomach, the food is mixed up and gently squeezed by digestive juice which contains different enzymes which chemically break down the food. This process is known as churning.

Inside the stomach, the digestion takes place during several hours producing a creamy paste called chime. This chime is then entering the small intestine by segmentation mechanism. Segmentation mechanism ten allows the mixing of food with digestive juice of intestinal muscles.

What is Chemical Digestion?

The chemical digestion is the process in which enzymes breakdown food into small molecules that the body can use and absorbs it. It is governed by chemical substances such as bile, acids, enzymes, which are secreted by alimentary canal.

Salivary glands and pancreas secrete the enzymes into the lumen of the alimentary canal which aids the digestion of proteins, lipids, and carbohydrates. The digestion of carbohydrate is done by amylase, secreted by the pancreas and salivary glands. The digestion of proteins is done by the action of protease enzyme in the stomach in acidic pH, also secreted by the pancreas. Lipids are digested in the small intestine by lipases secreted by the pancreas. The nucleic acid is digested by nucleases secreted by the pancreas, and the digestion is also done in the small intestine.

Key Differences

  1. Mechanical digestion is the mechanical breakdown of large food particles, whereas chemical digestion is the chemical breakdown of high molecular weight substances.
  2. Mechanical digestion follows the path from mouth to the stomach while chemical digestion normally goes from mouth to the intestine.
  3. A major portion of digestion takes place in the mouth in mechanical digestion; on the other hand, a major part of digestion happens in the stomach in chemical digestion.
  4. Mechanical digestion is driven by teethes and tongue; on the contrary, various enzymes and acids are responsible for driving chemical digestion.
  5. The physical breakdown of food by chewing is the mechanical digestion, whereas chemical digestion is the mixing of food with saliva.
  6. Mechanism of mechanical digestion involves the breakdown of large food particles into small food particles occur; on the flip side, in chemical digestion, the chemical breakdown of high molecular weight substances into low molecular weight substances takes place.
  7. Mechanical digestion plays its role in the body by increasing the surface area for the enzymatic actions to occur in chemical digestion; conversely, chemical digestion mainly boosts the absorption of nutrients by breaking down them down into small substances.

Conclusion

Above discussion concludes that mechanical digestion occurs in the mouth and responsible for mechanical breakdown of food particles by chewing while chemical digestion occurs by enzymes and it is chemical breakdown of high molecular weight substances.

Janet White

Janet White is a writer and blogger for Difference Wiki since 2015. She has a master's degree in science and medical journalism from Boston University. Apart from work, she enjoys exercising, reading, and spending time with her friends and family. Connect with her on Twitter @Janet__White

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