Digestion – An Overview

Introduction

Digestion is a vital process that involves breaking down food into smaller substances for absorption into the bloodstream. The digestive system, composed of various organs, plays a crucial role in this process.

The journey of digestion begins in the mouth, where food is mechanically broken down by chewing and mixed with saliva. From there, the food travels down the esophagus through peristalsis, a process involving muscle contractions that propel the food towards the stomach. In the stomach, digestive enzymes and hydrochloric acid further break down the food into a more usable form. Once adequately processed, the stomach releases the contents into the small intestine.

The small intestine is a remarkable organ responsible for absorbing approximately 90% of the nutrients from the food we eat. The walls of the small intestine absorb water and nutrients while allowing waste products to move into the large intestine.

The large intestine, comprising several segments, including the cecum, colon, and rectum, primarily absorbs water and converts waste into stool. Peristalsis helps move the stool into the rectum, where it is stored until elimination through the process of defecation.

While digestion is a complex and intricate process, it is not always flawless. Digestive disorders can occur, affecting the normal functioning of the digestive system. Common digestive disorders range from short-term conditions such as diarrhea and constipation to long-term conditions like GERD, irritable bowel syndrome (IBS), and celiac disease.

Some tips for promoting digestive health include eating consciously, chewing food thoroughly, staying hydrated, consuming a balanced diet rich in fiber, incorporating probiotic foods, managing stress levels, avoiding smoking and alcohol consumption, and involving in regular exercise.

The digestive system, consisting of various organs, works together to ensure that food is properly digested and absorbed. By understanding the process of digestion and adopting healthy habits, we can support our digestive system and promote overall wellness.

What is Digestion?

Digesting is breaking down food mechanically and chemically into smaller substances for absorption into the bloodstream. Fats, carbohydrates, and proteins are the three macronutrients that need digestion before absorption into the bloodstream.  
 
Digestion involves two distinct processes, namely physical and chemical digestion. Biological digestion is mechanically disintegrating food substances into molecules effectively through chemical digestion.  
 
The chemical digestion further disintegrates the ingested compounds by digestive enzymes into an absorbable form before joining the bloodstream. Effective digestion happens if these processes work equally; imbalance can lead to nutritional deficiencies and gastrointestinal pathologies. 

 Digestive System  

The digestive system does digestion. The digestive system refers to the network of organs that take food and digest & absorb nutrition from it.  
 
It comprises the gastrointestinal tract (GI) and ancillary organs like the liver, pancreas and gallbladder. The GI tract is a string of hollow organs from the mouth to the anus, namely the mouth, stomach, oesophagus, small intestine and large intestine, which has the rectum & anus. 
 
Your biliary system comprises the liver, gallbladder, pancreas and bile ducts, which supply enzymes and bile through to your GI tract your bile ducts. 

The process of digestion 

Mouth  

The mouth is the inception point of the digestive tract, and food starts its digestion journey from here. The other organs involved in the digestion process are teeth, salivary glands and tongue. 
 
Your teeth grind food into smaller pieces or bolus, and then saliva mixes with it and breaks it down. Then, the tongue passes the food into your throat and oesophagus.  

The oesophagus 

After swallowing, the bolus goes to the oesophagus, the brain signals the muscles of the oesophagus, and peristalsis begins. The gravity and muscle contractions help the bolus move down to the stomach through a process known as peristalsis. 
 
It is the measured contraction of smooth muscles along and near the digestive system. As the bolus travels through the oesophagus, these contractions deliver the food towards the stomach. 

Stomach 

The stomach is a muscular bag or “container” that holds food while mixed with stomach enzymes. It is located towards the left side of the abdominal cavity, below the diaphragm.  
 
The stomach produces digestive enzymes and hydrochloric acid. These enzymes carry on with breaking down food into a usable form. When the stomach contents are adequately processed, they’re released into the small intestine. 

Small Intestine 

The small intestine comprises three segments: the duodenum, jejunum, and ileum. It varies from 22 to 24 ft long depending on the height of the individual and absorbs 90% of the nutrients from the food. Digestive juices from the pancreas, liver, and intestine mix with food, and the small intestine muscles push the mixture for further digestion. 
 
The walls of the small intestine ingest the water and digested nutrients, and the waste products move into the large intestine.  

Large Intestine  

It is a long tube of 6ft consisting of a cecum, small intestine, ascending colon, transverse colon, descending colon and sigmoid colon. 
 
The large intestine absorbs water and converts the waste from the liquid into the stool. Peristalsis assists in moving the stool into your rectum. 

Rectum 

Waste products of digestion are passed into the end of the large intestine called the rectum and released out of the body as stool. It is collected in the rectum as semi-solid faeces, leaving the body through the anal canal through defecation. 

Common Digestive Disorders 

Digestive disorders are a category of conditions which occur when the digestive system does not function normally. There are two types of digestive disorders, namely organic and functional GI. 
 
Organic GI disorders happen when there is a structural irregularity in the digestive system, which prevents it from working correctly. The GI tract seems structurally normal in functional GI disorders but does not function well. 

Short-term conditions  

• Vomiting 
• Diarrhea 
• Hemorrhoids 
• Constipation 
• Gallstones 
• Heartburn 
• Stomach flu (gastroenteritis) 
• Ulcers 

Long Term Conditions 

• GERD (chronic acid reflux) 
• Lactose intolerance 
• Irritable bowel syndrome (IBS) 
• Diverticulosis and diverticulitis 
• Celiac disease  
• Cancer 
• Appendicitis 
• Hepatitis 

 Tips for a healthy digestive system 

Eat consciously and slowly chew your food 

• Drink water frequently 
• Add fibre to your diet 
• Consume a balanced diet 
• Eat pro-biotic foods  
• Avoid alcohol, drinking, and smoking 
• Handle your stress well 
• Do regular exercise 

Conclusion

Digestion is a complex process of converting food into energy for the body. Without this critical function, our body couldn’t extract energy and nutrients from our food.  

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