Key Difference – Bolus vs Chyme
The bolus is a mixture of food that is formed like a ball in the mouth while the chyme is a liquefied semi-solid mixture of food that is formed in the stomach. This is the key difference between bolus and chyme.
Ingested food is taken up by the gastrointestinal tract and undergoes different digestive steps with the involvement of different enzymes. For easy digestion, ingested food is formed into mixtures such as bolus and chyme. The bolus is formed in the mouth with the mixing of saliva and other fluids. The chyme is formed in the stomach that is mixed with hydrochloric acid. Bolus is alkaline in nature and chyme is acidic in nature.
CONTENTS
1. Overview and Key Difference
2. What is Bolus
3. What is Chyme
4. Similarities Between Bolus and Chyme
5. Side by Side Comparison – Bolus vs Chyme in Tabular Form
6. Summary
What is Bolus?
A bolus is defined as a mixture of food that is formed into a shape of a ball in the buccal cavity (mouth) that is mixed with saliva and enzymes. The pH of the bolus is alkaline since it is exposed and mixed with saliva. Ingested food first enters the buccal cavity. In the buccal cavity, food gets mechanically digested through chewing and due to the action of the tongue. It is then mixed with saliva into a ball-shaped mixture called the bolus.
Figure 01: Bolus
Saliva contains digestive enzymes such as salivary amylase (ptyalin), lipase, and lysozyme. Lysozyme contains antibacterial properties. Lipase involves the emulsification of lipids, and salivary amylase converts starch into maltose. The main function of saliva is to moisten and buffer the pH. Other than the digestive enzymes, saliva contains water and mucus that are added to the bolus in order to chemically break down ingested food and to facilitate the swallowing process through peristalsis.
What is Chyme?
Chyme is defined as a substance present in a state of semi-solid in the stomach. Chyme is formed by the breakdown of the bolus and is composed of partially or completely digested food, hydrochloric acid, water and different digestive gastric enzymes. The pH of chyme is acidic since it is exposed to hydrochloric acid. The partially digested food includes carbohydrates and proteins.
Chyme may also contain different cells that are added to the bolus from mouth and oesophagus during chewing and swallowing. Depending on the type of food, the formation of chyme and exposure time of chyme in the stomach are varied. If food that is ingested is rich in fats and proteins, the formed chyme will be of an oily nature.
Figure 02: Digestion of Stomach
Partial physical digestion of food leads to the formation of chyme with chunks of undigested food. These chunks of food will remain in the stomach for longer periods of time. Other than the type of food, few other factors decide the quality of chyme such as hormone levels, alcohol and tobacco consumption by the body and also chronic stress.the
What are the Similarities Between Bolus and Chyme?
- Both Bolus and Chyme are derived from ingested food.
- Both occur in the gastrointestinal tract.
- Both are stages of food digestion.
What is the Difference Between Bolus and Chyme?
Bolus vs Chyme |
|
| Bolus is defined as a mixture of food, saliva and enzymes that is formed into a shape of a ball in the buccal cavity (mouth) after the chewing process. | Chyme is defined as a semi-solid substance that is formed from the bolus in the stomach. |
| Source | |
| Food is the source where it is converted into the bolus. | The bolus becomes the chyme. |
| Conversion Location | |
| Conversion of food into bolus takes place in the mouth. | Conversion of the bolus into chyme takes place in the stomach. |
| Exposure | |
| Bolus is exposed to salivary enzymes. | Chyme is exposed to hydrochloric acid and gastric enzymes. |
| Location of Exposure | |
| The bolus is exposed in the mouth. | The chyme is exposed in the stomach. |
| Chemical Nature | |
| Bolus is alkaline in nature. | The chyme is acidic in nature. |
| Factors for Chemical Nature | |
| Salivary enzymes make the bolus alkaline. | Hydrochloric acid makes the chyme acidic. |
| Factors leading to the Conversion | |
| Actions of teeth and saliva convert food into a bolus. | Actions of gastric enzymes and HCL convert bolus into chyme. |
| Entering Site after Formation | |
| Bolus enters the stomach. | Chyme enters the small intestine. |
| Enzymes Involved | |
| Salivary enzymes such as amylase, lipase involve in bolus formation. | Gastric enzymes such as pepsin, trypsin , involves chyme formation. |
Summary – Bolus vs Chyme
Ingested food undergoes different digestive steps within the gastrointestinal tract. Foods are broken down, nutrients are absorbed, and wastes are eliminated from the body. During the whole process, ingested foods convert into different stages for easy digestion. Bolus and chyme are two states of foods going through the track. The bolus is formed in the mouth with the mixing of saliva and other fluids. Bolus takes alkaline nature due to saliva and other basic enzymes. The chyme is formed in the stomach. Chyme is composed of HCL and other gastric enzymes that are acidic. Hence, chyme takes an acidic nature. This is the difference between bolus and chyme.
Reference :
1. “Chyme: Definition & Function.” Study.com, Study.com. Available here
2.Britannica, The Editors of Encyclopaedia. “Chyme.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 11 Mar. 2014. Available here
Image Courtesy:
1.’Swallow food’By Boumphreyfr – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.’2429 Digestion of Proteins (Physiology)’By OpenStax College – Anatomy & Physiology, Connexions Web site. Jun 19, 2013., (CC BY 3.0) via Commons Wikimedia