The process of breaking down of large food particles 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 after 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 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.
Human digestive system comprises the alimentary canal and various digestive glands. The alimentary canal is a muscular tube, which extends from the mouth to the anus. The human digestive system comprises mouth, pharynx, oesophagus, stomach, small intestine, large intestine, and anus.
Let’s learn in detail about various parts of the human digestive system.
Mouth
The mouth is the first part of our digestive system. Food is ingested through the mouth.
Oral cavity
The oral cavity comprises the palate, tongue and teeth.
Palate – The roof of the oral cavity.
Tongue – Muscular and glandular structure attached to the base of the oral cavity. The upper surface of the tongue has tiny projections known as lingual papillae. Lingual papillae are of three types: circumvallate, fungiform and filiform.
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.
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 (Thecodont).
Pharynx
It is the common passage for food and air. Epiglottis prevents the entry of food into the windpipe.
Oesophagus
It is a muscular tube through which small bolus of food passes from the mouth to the stomach. The gastro-oesophageal sphincter controls the movement of food into the stomach.
Stomach
It is a muscular bag, positioned at the upper left part of the abdominal cavity. It has four parts- cardiac, fundus, body and pyloric portion.
- Cardiac part– It is present close to the heart. The opening of the oesophagus to the stomach is regulated by the gastro-oesophageal sphincter.
- Fundus– It is dome-shaped and is usually filled with air.
- Body– This is the main part of the stomach.
- Pyloric- It opens in the first part of the small intestine, duodenum. 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.
- Duodenum– It is C- shaped. The pancreatic, bile and hepatic secretions are added to the food by hepatopancreatic duct.
- Jejunum– Middle part of the small intestine.
- Ileum– It is highly coiled and opens into the large intestine.
Large Intestine
The small intestine leads into the large intestine. It has three parts- Caecum, Colon, and Rectum.
- Caecum– It is a small sac-like structure containing symbiotic microorganisms. The vermiform appendix (vestigial organ) is attached to it.
- Colon– It is divided into four regions- ascending, transverse, sigmoid and descending.
- Rectum– It opens into the anus.
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