Human Digestive System

The human body is a biological structure composed of several body systems. These body systems are groups of organs collaborating to maintain different bodily functions. The body has several systems like respiratory, cardiovascular, digestive, endocrine, lymphatic, and nervous systems, to name a few. The human digestive system plays a crucial role in maintaining our health. It aids in the absorption of nutrition required for our bodies’ development, upkeep, and activity from the food we consume. The article below concerns the digestive system’s structure and function in detail. 

Components of the digestive system

The organs of the human digestive system start from the mouth and end in the anal canal. Therefore, you can consider the structure of the human digestive system as a tube comprising the mouth, pharynx, oesophagus, stomach, small bowel, large bowel, and anal canal. The accessory digestive organs contributing to the mechanical and chemical food breakdown are the salivary glands, tongue, liver, pancreas, and gallbladder. 

• Mouth

The mouth or the buccal cavity is the starting point of the digestive tract. It is a specialised organ capable of receiving and breaking down large chunks of food. Biting and chewing degrade the food in the mouth. Saliva, a slippery and sticky fluid, moistens the food and combines bits of food into a soft and mushy mass. The tongue distributes food around and helps change it into a mass referred to as bolus while chewing. The bolus is driven through the entrance to the oesophagus after being pushed into the throat or pharynx. 

• Pharynx

The pharynx is where food goes after it has been swallowed. Food then passes to the oesophagus or food tube from here.

• Oesophagus

The oesophagus or the food tube is a tubular channel that transports food from the pharynx (oropharynx, to be specific) to the stomach. Upon examining the food tube anatomy, you will find three sections of the oesophagus. The cervical, thoracic, and abdominal sections. The oesophagus sends food down into the stomach through a sequence of contractions known as peristalsis. The lower oesophagal sphincter, located just before the entrance to the stomach, serves as a “valve” to prevent food from going back into the oesophagus.

• Stomach

The stomach resembles a container with thick muscular walls in the structure of the human digestive system. It holds the food, thereby aiding in its mixing with several hormones, acids, and enzymes. Food leaves the stomach in the form of a viscous paste. It then travels to the small bowel or small intestine. 

• Small bowel

The small intestine or the small bowel plays a crucial role in digesting the ingested food. It aids in food digestion using bile and pancreatic juices received through the pancreatic duct. The food is mixed with the digestive juices with the help of peristaltic movements. The duodenum breaks down the food while the jejunum and ileum absorb the nutrients from the food and liquids. 

• Large bowel

The large bowel or large intestine absorbs the remaining nutrients and water from the digested food and sends it back to the bloodstream. The stool thus formed is stored in the sigmoid colon until its evacuation into the rectum.

• Rectum

The rectum’s function is to receive stool from the colon and accommodate it till evacuation happens through the anus. 

• Anus

It is the last part of the digestive tract responsible for releasing the faeces from the body. 

Phases of digestion

Food is broken down into smaller and simpler components during digestion in the food tube anatomy until it can be assimilated and incorporated into the body. The 3 phases involved in digestion are;

• Cephalic phase

The initial step of digestion, known as the cephalic phase, begins with gastric gland secretions in reaction to the smell and sight of food. The mechanical degradation of food by chewing and the chemical degradation of food by digestive enzymes occur in the mouth during this stage. The digesting enzymes amylase and lingual lipase are released by the tongue’s serous and salivary glands. The mechanical digestion process begins with chewing, wherein the meal is combined with saliva. This creates a bolus, which is then ingested and sent down the oesophagus into the stomach.

• Gastric phase

The gastric phase begins the next stage of digestion in the stomach. The meal is further degraded in the duodenum, the first section of the small intestine, by interacting with gastric acid.

• Intestinal phase. 

The intestinal phase of the third stage commences in the duodenum, where partly digested food is combined with a variety of enzymes secreted by the pancreas. Peristalsis aids the overall digestion process. A rhythmic muscular contraction starts in the oesophagus and extends through the stomach wall and the remaining gastrointestinal tract. 

This causes the formation of chyme. It is then further degraded in the small intestine and incorporated in the form of chyle into the lymphatic system. The small intestine of the human digestive system is where the majority of food digestion takes place. In the large intestine’s colon, a few minerals and water are reabsorbed back into the bloodstream. The anus helps in the removal of waste products from the rectum.

Functions of the digestive system

The primary functions of the human digestive system include;

• Food breakdown and digestion

The digestive system mechanically and chemically degrades the foods we eat so that our bodies may utilise them for cell growth, energy, and repair. Proteins, carbs, lipids, vitamins, water and minerals, and other nutrients are broken down into simpler molecules to pass past the stomach lining and circulation.

• Secretion

The human digestive system secretes several enzymes, hormones, and other chemicals to assist the body in digesting the food it consumes. Hormones guide your body to generate digestive juices when you’re hungry or full.

• Absorption

The digestive system aids in the absorption of nutrients from the ingested food. These nutrients are passed from the gut to the bloodstream or the lymph systems. They then pass it on to other body parts for use or storage. 

• Movement of food

The peristaltic movement allows the ingested food to move around in the digestive tract. The movement includes everything from the degradation of ingested nutrients to the removal of waste from the body.

Conclusion

The human digestive system is one of the significant body systems aiding in the breakdown of food to release energy. It comprises the mouth, pharynx, food tube, stomach, small and large bowel, rectum, and anus. Several accessory digestive organs aid the digestion of food. They are the liver, gallbladder, pancreas, salivary glands, and tongue. The digestive system performs several vital functions like food movement, digestion, secretion of hormones and enzymes, and absorption of nutrients from the food.