Alimentary Canal Anatomy

Alimentary Canal Anatomy

May 08, 2023, 16:45 IST

The alimentary canal is a lengthy, coil-shaped tube that extends from the anus to the mouth. The throat, oesophagus, stomach, and small and large intestines are all places it travels through.

The alimentary canal is lined with a layer of epithelial tissue that protects it from the abrasive action of food and prevents food from leaking into the body.

The alimentary canal is a complex system with many essential functions. It digests food, absorbs nutrients, and eliminates waste. In addition, the alimentary canal is responsible for producing hormones and enzymes necessary for digestion.

This article will discuss the various structures that make up the alimentary canal, their morphology and their functions.

What is Alimentary Canal?

The alimentary canal, also known as the gastrointestinal tract, is a long, muscular tube starting at the mouth and ending at the anus. In between, several organs are responsible for the digestion and absorption of food.

The alimentary canal is a continuous tube with several valves and sphincters that control the flow of food and enzymes. These enzymes break down the food into nutrients that can be absorbed into the bloodstream. The alimentary canal is lined with a layer of mucus that protects the cells from the acidic environment.

• The length of the alimentary canal varies depending on the animal, but it is generally around 9-10m long in mammals. The organs of the alimentary canal can be divided into four central regions: the mouth, oesophagus, stomach, and intestines.
• The alimentary canal is a long, coiled tube that starts at the mouth and ends at the anus. It passes through the pharynx, oesophagus, stomach, and small and large intestines. The alimentary canal is lined up with a layer of mucus.
• The alimentary canal is vital in digestion, absorption, and elimination.
• The mucus protects the inside of the canal from the outside world. To learn more about alimentary canal anatomy, read the full article.

Organs Involved in the Alimentary Channel

• The mouth and oral cavity,
• Oesophagus,
• Stomach,
• Small intestine,
• Large intestine.

These comprise the main organs of the alimentary canal.

The Mouth

The mouth is the place where food enters our digestive system. It's the first opening in the digestive system, and it's closed by our lips. This is where we start eating food.

Salivary Glands

• The salivary glands play an important role in the alimentary canal, as they produce and secrete saliva into the mouth. Saliva moistens and lubricates the food, making it easier to swallow and pass through the oesophagus. It also contains enzymes that begin the breakdown of carbohydrates in the mouth, which helps with digestion later in the digestive system. Additionally, saliva helps to neutralise acids produced by bacteria in the mouth, which helps to prevent tooth decay and keep the mouth healthy.
• The salivary glands comprise three primary pairs - the submandibular, parotid, and sublingual glands. As we chew our food, it gets mixed with saliva in our mouth, forming a mass called a bolus. This mixture of saliva and chewed food is crucial for digestion, as it contains enzymes that help break down the food and prepare it for further processing in the digestive system.

Oral cavity

• Teeth - The adult human mouth contains 32 teeth, which aid in breaking down food by cutting and grinding it. The incisors and canines, located at the front of the mouth, are responsible for tearing and cutting food, while the bicuspids and molars, located further back, crush and grind the food into smaller pieces easier to digest.

• Tongue - The tongue, a muscular and fleshy triangular organ, is situated on the floor of the buccal cavity. Its primary function is to aid digestion by mixing the food with saliva and pushing it to the pharynx and oesophagus. The tongue's top surface is covered with small projections called papillae, which contain sensory receptors called taste buds that help us perceive different flavours. Without taste buds, our experience of food would be greatly diminished.

Pharynx

• The pharynx, also known as the throat, plays a crucial role in the digestive system as it serves as a common pathway for both food and air. When we swallow, the tongue and soft palate push the chewed food to the back of the mouth and into the pharynx. The pharynx then contracts to move the food down into the oesophagus, which leads to the stomach.
• The pharynx also contains the epiglottis, a flap of tissue that covers the trachea (windpipe) when we swallow, preventing food from entering the airway and lungs.

Oesophagus

• The oesophagus, also known as the food pipe, is a muscular tube that connects the pharynx to the stomach. Its primary function is transporting food from the mouth to the stomach using peristalsis, a series of coordinated muscular contractions that propel food down the oesophagus.
• The lower end of the oesophagus contains a muscular valve called the lower oesophagal sphincter (LES) which relaxes to allow food to enter the stomach and then contracts to prevent stomach contents refluxing back into the oesophagus.
• The oesophagus plays a critical role in the digestive system by facilitating food movement from the mouth to the stomach, ensuring it is properly digested and absorbed.

Stomach

• The stomach is a muscular sac located in the upper left of the abdomen and is a crucial digestive system component.
• The primary function of the stomach is to mechanically and chemically break down food that has been swallowed.
• The stomach secretes gastric juice comprising hydrochloric acid, enzymes, and mucus. Hydrochloric acid helps to denature proteins, while the enzymes help to break down carbohydrates and proteins into smaller molecules that the small intestine can absorb.
• The mucus lining of the stomach helps to protect the stomach from the corrosive effects of the acid.
• The stomach mixes and grinds the food into a thick, soupy mixture called chyme, which is then slowly released into the small intestine through the pyloric sphincter.
• The stomach can be categorised into five distinct sections: the cardiac stomach, the fundus stomach, the body, the antrum stomach, and the pyloric stomach.

Function Of Alimentary Canals

The alimentary canal's fundamental job is to absorb and digest nutrients from meals. Aside from these fundamental activities, the alimentary canal conducts several other critical functions.

• Carbohydrates, proteins, fats, vitamins, minerals, and water are examples of nutrients. Your digestive system breakdowns and consumes the nutrients in the food and fluids you ingest, which it uses for energy, development, and cell repair.
• The colonic bacterial colony also stops dangerous germs from growing in our alimentary tract.
• The practice of consuming is referred to as ingestion.
• Drug metabolism also happens in the alimentary canal, where the drug molecule is broken down into smaller fragments and removed from the body. Antigen metabolism also occurs in the alimentary canal, cleansing the body of antigens.

Alimentary Tract Dysfunction Symptoms

When a condition is chronic, inanition is the primary physiological consequence, dehydration is the primary effect in acute diseases, and shock is the primary physiological disruption in hyperacute diseases. Most gastrointestinal tract disorders often cause some level of stomach discomfort, with the intensity varying depending on the kind of lesion. Some other symptoms are prehension, mastication, swallowing irregularities, nausea, vomiting, diarrhoea, bleeding, constipation, and sparse faeces.

Prehension, mastication, and swallowing anomalies

• Prehension

Prehension uses the mouth to grip something to eat. (lips, tongue, and teeth). It includes the capacity to consume alcohol. Poor prehension can be brought on by

Jaw or tongue muscles that are paralysed.

The following causes incisor tooth malposition-

Rickets

Hereditary skeletal defects such as

• congenital osteopetrosis,
• mandibular prognathism, and
• misplaced molar teeth.

Some incisor teeth may be missing.

Several things can induce mouth pain:

• Foreign body in the mouth; fluorosis; stomatitis; glossitis; and decayed teeth.

Congenital lip- and tongue-related anomalies:

• Harelip and cattle's smooth tongue inheritance

• Mastication

Chewing may be uncomfortable and show signs of delayed jaw motions broken up by pauses and pain expressions if an ailing tooth is a culprit. Still, in severe stomatitis, there is typically a complete unwillingness to chew. Food falling from the mouth when eating and the transit of significant amounts of undigested material in the faeces are signs of incomplete mastication.

• Swallowing Difficulties

The glossopharyngeal, trigeminal, hypoglossal, and vagal nerves are responsible for reflexes controlling the complicated swallowing act. Endoscopic and fluoroscopic descriptions of it have been made on horses. Closing all pharyngeal openings, applying pressure to drive the bolus into the oesophagus, and involuntary movements of the oesophagal wall muscles to transport the bolus to the stomach make up the mechanics of the act. Swallowing difficulties might result from a problem with the neurological system controlling the reflex or from a constriction of the pharynx or oesophagal lumen. It is challenging to distinguish clinically between physical and functional reasons for dysphagia (difficulty swallowing or eating).

• Causes of Swallowing Problems and Dysphagia

• Esophageal blockage by impacted food material;
• Esophageal dilatation brought on by paralysis;
• Esophageal diverticulum;
• Esophageal spasm at site of mucosal erosion;
• Foreign body, tumour, or inflammatory swelling in pharynx or oesophagus;
• Painful condition of pharynx or oesophagus (achalasia of cardio not encountered).

• Causes of Drooling

• Mouth or pharynx foreign body,
• Swallowing difficulties,
• Profound oral mucosal erosion, or
• Vesicular eruption (oesophagal abnormality).

• Systemic Causes of Excessive Salivation

• Poisonous Trees: Oleander spp., Andromeda spp. (Rhododendron),
• Other Poisonous Plants: Kikuyu Grass (or an Adjoining Fungus),
• Fungal Toxins, such as Slaframine and those Causing Hyperthermia, such as Claviceps Purpurea and Acremonium Coenoph,
• Sweating illness,
• Methiocarb poisoning,
• Watery Mouth in Lamb,
• Iodism.

• Causes of vomiting and regurgitation

• Terminal vomiting in horses with acute gastric dilatation.
• Cattle "vomiting" is the mouth-regurgitation of many rumen contents. The following are some causes:
• Milk fever in its third stage (loss of tone in the cardia)
• Arsenic toxicity (acute inflammation of the cardia)
• Plants include Eupatorium rugosum, Geigeria spp., Hymenoxys spp., Andromeda spp., Oleander spp., and Conium maculatum that can poison you.
• Large amounts of fluids are injected into the rumen by a veterinarian. (regurgitation occurs while the stomach tube is in place)
• Utilization of a large-bore stomach tube.
• Cud-dropping: a unique kind of regurgitation typically accompanied by cardia abnormalities.

• Causes of constipation or sparse faeces

• Severe debility, as in old age,
• Lack of dietary bulk, typically fibre,
• Chronic dehydration,
• Partial obstruction of the large intestine,
• Painful conditions of the anus,
• Paralytic ileus,
• Grass sickness in horses,
• Diseases of the forestomach and abomasum causing failure of outflow.

Frequently Asked Questions (FAQs)

Q1. What are the three different parts of alimentary canals?

Ans. The digestive tract, the transport route, and the mouth cavity comprise the three main functioning elements of the alimentary system.

Q2. What are the seven digestive organs?

Ans. Some of these organs are the anus, throat (throat), stomach, small and large intestines, rectum, and oesophagus.

Q3. What are the alimentary canal's primary layers?

Ans. There are four layers, or tunics, covering the wall of the digestive tract:

• Mucosa.
• Submucosa.
• muscle layer.
• Serosa, also known as the serous layer.

Q4. How is the stomach shaped?

Ans. In the upper abdomen, the stomach is an organ with a J shape. It belongs to the gastrointestinal system. It lies between the beginning of the small bowel's first segment and the end of the oesophagus. (duodenum). In many ways, the stomach resembles a bag with a lining.