Alimentary Canal

Introduction

The digestive system is made up of organs that digest food, assimilate its nutrients, and eliminate any leftover waste. The gastrointestinal (GI) tract, which connects the mouth to the anus, is essentially a long, continuous tube. For a variety of harmful bacteria, the alimentary canal serves as an immunological barrier. Gut-associated lymphoid tissue (GALT) and the various pH conditions that exist throughout the alimentary canal perform this role.

What is the Alimentary Canal?

Because of their complicated body plans, humans have a digestive tract with two openings: a mouth at one end and an anus at the other. The food material travels in a single path along the alimentary canal as it passes through several specialised organs. The Alimentary Canal is a similar tube whose main purpose is to facilitate food particle circulation and ultimately assist in nourishment.

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Parts of Alimentary Canal 

Mouth: The mouth, also known as the oral cavity or buccal cavity, where the alimentary canal starts, contains teeth and a tongue that help break down food particles.

Pharynx: It is commonly referred to as the throat area. When food is swallowed, it travels via the pharynx.

Oesophagus: The throat and stomach are connected by a lengthy tube called oesophagus.

Stomach: The stomach is a structure that resembles an extended pouch that is situated between the oesophagus and the small intestine. Here, the food is transformed into a liquid suspension to facilitate absorption.

Small Intestine: As a result of the high rate of nutrient absorption in this area, it is sometimes referred to as the “workhouse” of digestion. It is the Alimentary Canal’s longest section.

Large Intestine: The alimentary canal’s terminus is located here. The “leftovers” in this area are used to absorb water and vital nutrients, which are eventually expelled through the anus

The Structure and Parts of Stomach

• The lower surface of the stomach’s curve to the left and the upper surface to the right is referred to as the lesser and larger curvatures, respectively. 
• The fundus, body, and pylorus are its three parts. The fundus, which is the main part of the stomach, is elevated above the esophageal entrance. 
• The stomach’s body and pylorus are it’s middle and base, respectively. 
• The incisura angularis is the point where the body region and the proximal antrum converge.
• The muscularis mucosa, a thin layer of smooth muscle, is composed of the inner mucus epithelium, a bigger loose connective tissue called laminar propria, and the innermost layer of the gastrointestinal wall, known as the mucosa.
• Connective tissue, blood vessels, alveolar tissue, and Meiisner’s nerve plexus make up the submucosal layer.

Which are the Parts of the Alimentary Canal and What are their Functions?

Parts of Alimentary Canal	Structure	Functions
Buccal Cavity	The vestibule and actual oral cavity make up the mouth.  A hard palate is the roof of the mouth, which divides the nasal cavity from the oral cavity. The muscular tongue has numerous taste buds and covers the base of the mouth. Dentin makes up teeth, which are covered in enamel, the toughest tissue.	Ingestion of food. Tongue helps in producing the sense of taste by detecting chemicals present in food. Teeth chew and grind the food material into smaller pieces. During mastication, incisors are used for cutting the food pieces, canines for tearing, premolars and molars for chewing and grinding.
Pharynx	It is a muscular structure resembling a tube.  It connects to the oesophagus and the trachea, two passages.	Here, swallowing is carefully timed to prevent food particles from entering the trachea.
Oesophagus	It is a muscular, extensible, mucus-coated tube that runs from the pharynx to the stomach.  At each end, a muscular sphincter protects it.	Peristalsis causes the bolus to move toward the stomach. The lower or cardiac sphincter stops food from passing from the stomach back into the oesophagus.
Stomach	Just behind the diaphragm is where the stomach is located. Chief cells, which secrete the enzymes found in gastric juice, parietal cells, which secrete hydrochloric acid, and intrinsic factors, which work in conjunction with vitamin B12 to preserve the lining of the stomach wall, cover the inner surface of the stomach and its glands.	Releases hydrochloric acid, which helps to break down food particles, and activates dormant pepsinogen to produce pepsin, which aids in the breakdown of proteins.  Along with food, it also contributes to bacterial death.
Small Intestine	In the abdominal cavity, the small intestine looks like a lengthy, coiling loop.  There is a brief duodenum section, then the jejunum region, and the longest region, the ileum.  The mucosal layer, which is the small intestine’s innermost layer, is covered in numerous microscopic folds known as villi.  The vermiform appendix, a structure that resembles a worm and is located at the back of the small intestine, has no known physiological function.	The small intestine’s surface area is increased by microvilli, which improves food absorption.  In the small intestine, the presence of secretory cells at the base of crypts prevents bacterial development.  The duodenum is where food is continuously broken down, whereas the jejunum and ileum primarily help the body absorb the food that has been digested.
Large Intestine	It resembles a large muscular tube connecting the rectum and small intestine.  It consists of the anus, colon, rectum, and caecum.  There are sigmoid, transverse, ascending, and descending sections in the colon.  The caecum is a structure resembling a pouch.	The lubricating mucus covered in faeces is produced by the existing intestinal mucus glands.  Here, undigested food stuff concentrates and salts and water are absorbed.  The rectum acts as a holding area for faces.

Summary

Because of their complicated body plans, humans have a digestive tract with two openings: a mouth at one end and an anus at the other. The lower surface of the stomach’s curve to the left and the upper surface to the right are referred to as the lesser and larger curvatures, respectively. In the abdominal cavity, the small intestine looks like a lengthy, coiling loop. The lubricating mucus covered in faces is produced by the existing intestinal mucus glands.

Frequently Asked Questions (FAQs)

1. What is the Function of the Epiglottis?
Ans. Epiglottitis is a flap-like structure that covers the glottis, the windpipe’s entrance, when food is swallowed. This stops the food from choking and entering the windpipe.

2. What Function does Meiisner’s Nerve Plexus Serve?
Ans. Meissner’s nerve plexus controls the gastrointestinal tract’s secretions and local blood flow and aids in the start of the peristaltic movement.

3. Where are Delta Cells Found and what do they do?
Ans. The pancreatic islets of Langerhans contain delta cells. Somatostatin, a hormone that prevents the body from producing other hormones, is produced by these cells.

4. What Pigments are Present in Bile, and where do they Come From?
Ans.  The bile pigments include greenish biliverdin and yellowish bilirubin. Dead red blood cells’ haemoglobin is degraded, and the bile pigments that result are expelled.

5. What Function does E. coli Serve in the Human Digestive System?
Ans. E. coli is a type of bacteria that helps with digestion, breaking down food particles for absorption in the small intestine and producing vitamin K.