Alimentary Canal -Anatomy

The process of breaking down large insoluble food fragments into smaller and water-soluble particles, which can be easily absorbed by the blood plasma is termed as digestion. All parts of the body are involved in the uptake and digestion of food along with the elimination of undigested material.

What is the Alimentary Canal?

The alimentary canal is mainly referred to as the pathway by which food enters our body and moves out through the anus during digestion. It is a tube-like structure which starts from the mouth and ends in the anus. The alimentary canal plays a primary role in the human digestion and is also termed as the digestive tract.

Organs of the Alimentary Canal

The main organs of the alimentary canal are:

  • The Mouth and Oral cavity.
  • Oesophagus.
  • Stomach.
  • Small intestine.
  • Large intestine.

The structure and functions of these organs are discussed below.

Large Intestine

Human digestive system which is also known as the alimentary canal is a muscular tube which extends from the mouth to the anus. The parts of the human digestive system include – mouth, oral cavity, teeth, oesophagus, pharynx, stomach, small intestine, large intestine, and anus.

Mouth

The mouth is the opening through which the intake of food occurs.

Oral cavity

The oral cavity has three parts –the palate, tongue, and teeth.

Palate

It forms the roof of the oral cavity. The anterior part is called hard palate and the posterior part is called the soft palate.

Tongue

The tongue is a muscular and glandular structure attached to the base of the oral cavity. On the upper surface, it has a V-shaped furrow called sulcus terminalis. It divides the tongue into the anterior oral part and posterior pharyngeal part. Its upper surface also consists of tiny projections called lingual papillae. Lingual papillae are of three kinds in humans-

(i) Vallate or circumvallate papillae -have gustatory receptors to sense taste

(ii) Filiform papillae- smallest and contain touch receptors.

(iii) Fungi-form papillae- Rounded and mostly present at the tip of the tongue.

Also Read: Structure of Tongue

Teeth

Humans are diphyodont i.e. they have two sets of teeth- milk or deciduous and permanent teeth. Here is the list of different types of teeth in humans with their functions.

Type of teeth Function
  Incisors   Used for cutting
  Canines   Used for tearing
  Premolars   Used for Chopping
  Molars  Used for Grinding and Chewing

The structure of the tooth is made up of three parts- the crown, neck, and root. The exposed part of the tooth is called the crown, the region where it is covered with gums is known as neck and root is embedded in the socket of the jaw bone.

Pharynx

It forms the common passage for food and air.

Oesophagus

It is a muscular tube through which small bolus of food passes from the mouth to the stomach. Oesophagus is sharply bent at the point at which it meets the stomach. This prevents the backward movement of food from the stomach into it. Food in the digestive tract moves by an involuntary movement of alternate contraction and relaxation of muscles called peristalsis.

Stomach

It is a muscular bag which has three parts- cardiac part, fundus, and body.

  1. Cardiac part– It is so-called because it is present close to the heart. The opening of the oesophagus to the stomach is regulated by the cardiac sphincter.
  2. Fundus– It is dome-shaped and is usually filled with air.
  3. Body– This is the main part of the stomach. The opening of the stomach into the small intestine is regulated by the pyloric sphincter.

Small Intestine

It is the longest part of the alimentary canal and comprises three parts- Duodenum, Jejunum, and Ileum.

  1. Duodenum– It is C- shaped and receives the hepatopancreatic duct formed by the union of bile and pancreatic duct.
  2. Jejunum–  Middle part of small intestine with thick walls and more vasculature.
  3. Ileum– The lower part of the small intestine with thin walls and less vasculature.

Large Intestine

The small intestine leads into the large intestine, which has three parts- Caecum, Colon, and Rectum.

  1. Caecum– It is a small sac-like structure at the point where the small intestine meets the large intestine.
  2. Colon– It is divided into four regions-  transverse colon, sigmoid colon ascending colon and descending colon.
  3. Rectum– It opens into the anus.

Also Read: Gastrointestinal Tract

To learn more about the Alimentary Canal and Human Digestive System, visit BYJU’S.

 

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