Alimentary Canal Anatomy

The alimentary canal, also known as the gastrointestinal tract, is a long tube-like structure, that starts from the mouth and ends to the anus. The alimentary canal length is 8 to 9 meters long. It is also termed the digestive tract, which is responsible for digestion by breaking down food, absorbing nutrients, and expelling waste.

Alimentary Canal Anatomy And Physiology

Food passes through the alimentary canal by way of the mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. As the body digests food, each part of the alimentary canal performs a distinct function to ensure that energy, growth, and repair nutrients are delivered into the body. Going further, let us discuss each part of the alimentary canal, that delivers different roles in digestion of the food.

Parts Of The Alimentary Canal And Their Functions

The main organs of the alimentary canal include the following –

1. The Mouth and Oral cavity.
2. Oesophagus.
3. Stomach.
4. Small intestine.
5. Large intestine.

We will discuss the structure and function of these organs in the following sections.

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Mouth and oral cavity

The mouth is the starting part of the alimentary canal, and food is ingested through the mouth. Digestion starts at the mouth both chemically and mechanically.

• The mouth is lined with mucous membranes and contains structures such as the teeth, tongue, and salivary glands.
• Teeth break down the food into smaller pieces by a process called mastication, while the tongue helps to mix the food through saliva.
• A salivary enzyme called amylase aids in carbohydrate digestion.
• In the pharynx, a bolus is formed after the food has been sufficiently broken down and moistened.

Pharynx

The pharynx is a muscular tube located at the back of the throat. It is a muscular organ that connects the mouth to the esophagus. The pharynx serves as a pathway for air to the lungs.

• It consists of three regions: the nasopharynx (behind the nose), oropharynx (behind the mouth), and laryngopharynx (above the esophagus and windpipe).
• Epiglottiss is a flap of tissue that closes off the entrance of the trachea from food during swallowing.

Eosophagus

The esophagus is a tube that carries food and liquids from your throat to your stomach. After you swallow, muscles in the walls of the esophagus contract in a wave-like motion, pushing the food down toward the stomach. This process is called peristalsis.

• The esophagus is about 25 centimeters long.
• It runs behind the windpipe and heart, eventually connecting to the stomach.
• A special muscle called the lower esophageal sphincter helps keep stomach acids from flowing back into the esophagus, protecting it from irritation.

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Stomach

It is a J-shaped muscular organ. The location of the stomach is in the upper left part of the abdominal cavity. It is a place where food gets mixed chemically and mechanically. The inner lining of the stomach contains gastric glands that secrete gastric juice.

• Gastric juice includes hydrochloric acid (HCl) and digestive enzymes such as pepsin.
• These substances help to break down proteins into smaller peptides.
• The stomach has three main regions: the fundus, body, and pylorus.
• The muscular walls of the stomach churn the food, mixing it with gastric juice to form a semi-liquid substance called chyme.
• The pyloric sphincter controls the passage of chyme from the stomach into the small intestine.

Small intestine

The small intestine is a long, coiled tube in your abdomen that helps digest food and absorb nutrients into your body.

• It comes after the stomach and is made up of three parts: the duodenum, jejunum, and ileum.
• As food moves through the small intestine, digestive juices from the pancreas and liver break it down further.
• Tiny finger-like structures called villi line the walls, allowing nutrients like vitamins, minerals, and proteins to be absorbed into the bloodstream.
• The small intestine is crucial for getting the energy and nutrients your body needs from food.

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Large intestine

The large intestine is the last part of the digestive system. Its main job is to absorb water and salts from the leftover food that couldn’t be digested in the small intestine.

• As water is absorbed, the waste becomes more solid and turns into stool.
• The large intestine is shorter but wider than the small intestine and is made up of the colon, rectum, and anus.
• Bacteria in the large intestine help break down some remaining food and produce vitamins.
• At the end of the process, the stool is stored in the rectum and then passed out of the body through the anus during a bowel movement.
• The large intestine is divided into several sections: the cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum, and anus.
  Cecum: The first part of the large intestine, the cecum, receives the chyme from the small intestine.
• Colon: As the chyme moves through the ascending, transverse, and descending portions of the colon, water and electrolytes are absorbed. After this, the material begins to solidify into feces
• Rectum and Anus: The rectum serves as a temporary storage site for feces until they are ready to be expelled through the anus.

Accessory organs

They play an important role in digestion. While not being a part of alimentary canal, it helps in aiding digestion of the food and includes the following organs – liver, pancreas, and gall bladder. Lets discuss the accessory organs in brief.

• Liver: The liver produces bile, which helps to emulsify fats, making them easier to digest. Bile is stored in the gallbladder and released into the duodenum when needed.
• Pancreas: The pancreas produces digestive enzymes (such as lipase, amylase, and proteases) and bicarbonate. This neutralizes the acidic chyme entering the small intestine from the stomach.

FAQs on Alimentary Canal

What is the alimentary canal?

Alimentary canal is long muscular pipe, that starts from the mouth and ends to the anus. It is an 8 to 9 meters long tube through which food travels as it is digested.

What role does the stomach play in the alimentary canal?

The stomach helps in churning the food with the help of enzymes produced in it. This helps in breaking the proteins and digesting the food.

What are villi and what do they do?

Villi are small finger like structures, present in the inner walls of small intestine. This helps in absorbing the nutrients and transfer nutrients from digested food into the blood

How does food move through the alimentary canal?

Food moves into the stomach through persitaltis movement, which is a wave-like motion that pushes food forward into the body

What are accessory organs in digestion, and how do they relate to the alimentary canal?

The accessory organs are gall bladder, liver and pancreas. They assist the alimentary canal by producing and storing digestive enzymes and bile. These enzymes help break down food in the small intestine.