The alimentary canal is one of the most important parts of the digestive system. It is a long, continuous muscle tube that runs through the body, measuring around 8 to 10 metres in length. It is open on both ends, with the mouth on the front and the anus on the back. The alimentary canal is responsible for food digestion. It breaks it down into tiny bits and helps the digested food be absorbed.

The Alimentary Canal Consists: 

• The Mouth

The mouth is where food enters the gastrointestinal tract. The upper lip and lower lip block the upper and lower openings of the alimentary canal. This is the point at which food is consumed.

• Salivary Glands

When we eat, smell, or even think about food, saliva is created by the salivary glands and discharged into the buccal cavity. Mastication (the act of chewing food) breaks the meal down into smaller particles when it enters the mouth, allowing salivary enzymes to work on the broken-down food.

• Teeth

There are 32 teeth in the buccal cavity of an adult. Our teeth assist us in breaking down and crushing food. The incisors and canines (front teeth) cut and rip food, while the bicuspids and molars (back teeth) crush and grind it into smaller pieces that are simpler to digest.

• Tongue

The tongue is a triangular organ with three lobes. It has a meaty and muscular appearance. It runs the length of the buccal cavity’s floor.

• Pharynx

At the back of the mouth, the pharynx is located. It is the point where the mouth meets the oesophagus. It is a common pathway for both the food we eat and the air we inhale. The epiglottis, a cartilaginous flap, protects the glottis, which is the name of the aperture of the respiratory system in the pharynx.

• Oesophagus

In the presence of peristaltic motions, the oesophagus is a muscular, tubular structure that transports the bolus from the pharynx to the stomach. In a healthy adult, it’s about 25 cm long. It contains epithelial cells that secrete mucus, which helps the bolus travel smoothly. When the bolus is ready to enter the stomach, the oesophageal sphincter, also known as the cardiac sphincter, relaxes and allows the bolus to flow into the stomach.

• Stomach

The stomach is a pouch-like structure with extremely muscular walls that sits directly beneath the diaphragm.

The Mechanism – In digestion, the stomach conducts both chemical and mechanical activities.

The upper involuntary muscles of the stomach relax to allow more food to be stored, while the lower muscles contract repeatedly to mix and churn the food with the stomach’s gastric secretions.

Hydrochloric acid, the major gastric acid, and gastric enzymes such as Pepsin, Gastric Amylase, Lipase, and Gelatinase aid in the further breakdown of food in chemical terms.

This partially digested meal becomes Chyme, a thick, creamy, semi-solid material that is pushed down the small intestine (duodenum).

• Small Intestine

The small and large intestines are the two parts of the human gut. As a result, the small intestine is the portion of the intestine that comes after the stomach but before the large intestine. It is broken into the following sections:

1. The Duodenum: The Duodenum is the initial segment of the small intestine, beginning at the bottom of the stomach and extending to the jejunum. It’s the division where enzymes are used to break down chemicals.
2. The Jejunum is the small intestine’s centre division, and it plays a key role in carbohydrate and protein absorption. The inner surface of the jejunum, known as the mucous membrane, is covered in small, finger-like projections known as villi, which increase the surface area of tissue available to absorb nutrients from the gut contents.
3. The ileum is the section of the gut that connects the jejunum with the large intestine. It is the small intestine’s final and most likely longest segment. The ileum’s primary role is to absorb Cobalamin (Vitamin B12), bile salts, and any other digestive products that the jejunum was unable to absorb.

• Large Intestine

The large intestine starts in the right iliac region of the pelvis, just below or at the right waist, and connects to the small intestine at the lower end. It is usually 1.5 metres (4.9 feet) long, accounting for about a fifth of the length of the alimentary canal.

Large Intestine Components:

1. Appendix: The appendix is an inner organ that is linked to the inferior surface of the cecum and has no known function.
2. Cecum: The cecum is a pouch-like structure that is generally peritoneal and is thought to be the beginning of the large intestine.
3. Colon: The last segment of the digestive tract is said to be the big intestine. This is located between the ileum and the anus. The colon is made up of the following parts:

The section of the colon that extends up the belly is known as the ascending colon.

The section of the colon that goes across the width of the abdominal cavity is known as the transverse colon.

The descending colon is the section of the colon that descends towards the sigmoid colon’s beginning.

The S-shaped segment of the large intestine, which is also the final part of the colon, ends in the rectum, is known as the sigmoid colon. The strain on this colon during constipation can put the person at risk for diverticulitis.

4. Rectum: The rectum is the final section of the large intestine, where faeces are momentarily held before being discharged into the anal canal. It has a length of around 15 centimetres and is separated into two sections: the rectum proper and the anal canal.

The alimentary canal is a tube-like structure that begins in the mouth and terminates in the anus. It is also known as the digestive tract and plays a crucial function in food digestion.

Conclusion

Food is moved through the GI system during digestion. Chewing starts digestion in the mouth and ends in the small intestine. Food combines with digestive secretions as it moves through the GI system, causing big molecules of food to bind together.