Alimentary Canal

The Alimentary Canal

The Alimentary Canal, also known as the digestive tract, is a vital part of human nutrition, responsible for the entire digestion process from ingestion to excretion.

Structure of the Alimentary Canal

  • The alimentary canal is a continuous tube that runs from the mouth to the anus.
  • The main parts include the mouth, pharynx, oesophagus, stomach, small intestine, large intestine, and the anus.
  • Each part of the canal has a specialised function in the digestion and absorption of food.

Function of Each Part

Mouth

  • The mouth initiates digestion with the mechanical breakdown of food by chewing, and the chemical breakdown by salivary enzymes.
  • Saliva produced in the mouth contains the enzyme amylase, which begins the digestion of starch into maltose.

Pharynx and Oesophagus

  • The pharynx and oesophagus act primarily as transport passages, moving food from the mouth to the stomach.
  • The process of swallowing involves both voluntary and involuntary muscle movements.

Stomach

  • The stomach further breaks down the food into a semi-fluid mass called chyme, using both mechanical and chemical digestion.
  • The stomach secretes gastric juices which include hydrochloric acid to kill bacteria and provide the pH for enzyme optimisation, and the enzyme pepsin which begins protein digestion.

Small Intestine

  • The small intestine is the major site for digestion and absorption.
  • It secretes intestinal juices which include enzymes to complete the digestion of proteins, carbohydrates, and fats.
  • It is lined with villi and microvilli to increase the surface area for optimal absorption of nutrients.

Large Intestine

  • The large intestine absorbs water and salts, resulting in the formation of solid faeces.
  • It houses a large number of symbiotic bacteria which synthesise certain vitamins like Vitamin K and B complex, further absorbed by our body.

Anus

  • The anus is the exit point of the alimentary canal where indigestible material is egested as faeces.

Understanding the structure and functionality of each part of the alimentary canal will greatly enhance your comprehension of the overall human nutrition process.