Functions of Saliva

  • Saliva is a secretion of salivary glands.
  • Contains maximum water content (99.5%) and 0.5% solids.
  • Includes solid content like organic, inorganic and gases also.
  • Various important functions which leads to many inconveniences if absent.

A) Swallowing of food

  • Moistening of food occurs when food is taken from mouth.
  • Dissolving of food also assisted by saliva.
  • Besides above function chewing is also facilitated.
  • Food moistened and masticated is thus moved by tongue.
  • Converts food to bolus by rolling.
  • Swallowing is facilitated by mucin present in saliva which acts as lubricants.

B) Appreciation of taste

  • Solvent action of saliva helps to identify taste sensation.
  • Taste is a chemical sensation.
  • Chemicals in solid food get dissolved in saliva which stimulates the taste buds.
  • Thus, taste is recognized by the stimulated taste bud.

C) Digestive function

  • Three vital digestive enzymes are contained by saliva.
  • Salivary amylase, maltase and lingual lipase are the major enzymes.

Salivary amylase

  • Is a carbohydrate-digesting enzyme also called amylolytic enzyme.
  • Function more in boiled starch or cooked form.
  • Starch converts to dextrin and maltose.
  • In mouth, digestion of starch initiates but for short time.
  • Major digestion takes place in stomach as stomach hold food longer than mouth.
  • Optimum pH of 6 activates salivary amylase.
  • But, this enzyme cannot act on cellulose.


  • Only traces of maltase are present in human saliva.
  • Maltose is acted upon and is converted to glucose.

Lingual lipase

  • Enzyme that digests lipid also called lipid digesting (lipolytic) enzyme.
  • Serous glands secrete this enzyme.
  • Located on the posterior aspect of tongue.
  • Pre-emulsified fats i.e., milk fats generally digested by this enzyme.
  • Triglycerides are acted upon to convert to fatty acids and diacylglycerol.

D) Protective and cleansing functions

  • Rinses mouth and teeth constantly as it is secreted constantly.
  • Food debris is kept away.
  • Epithelial and foreign particles are shedded.
  • Thus, bacterial growth is kept away as these things can act as a culture media.
  • An enzyme is present in saliva called lysozyme.
  • This enzyme kills bacteria like Staphylococcus, Streptococcus and Brucella.
  • Antimicrobial property is present in saliva content i.e., proline-rich proteins.
  • These proteins neutralize toxic substances like tannins.
  • Tannins are substances found in fruits and many other food substances.
  • Antimicrobial property is also shown by lactoferrin content.
  • Enamel formation is stimulated by lactoferrin and proline-rich proteins.
  • Thus, teeth remains protected.
  • Antibacterial and antiviral property also found as saliva contains IgA.
  • Mucus membrane of mouth remains protected by mucin content of the saliva.

Physiological functions of saliva | Download Scientific Diagram

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E) Role in speech

  • Moistens and lubricates soft parts of the mouth, lips.
  • Thus, this function of saliva helps in speech.
  • Dry mouth does not allow proper articulation and pronunciation.

F) Excretory function

  • Organic as well as inorganic substances are excreted in saliva.
  • Substances like mercury, lead, thiocyanate, potassium iodide.
  • Some viruses are excreted such as those causing rabies and mumps.
  • Saliva also secretes those substances that it does not secrete in normal conditions.
  • Only in pathological conditions they are secreted.
  • Glucose is secreted in diabetes mellitus condition.
  • Not only that some saliva constituents are excreted in large quantities.
  • Excess urea is excreted in nephritis from saliva.
  • Likewise in hyperparathyroidism, excess calcium is excreted.

G) Body temperature regulation

  • Dripping of saliva occurs excessively in some animals like dogs and cattles.
  • This happens during panting that help them to loss heat.
  • Thus, temperature of body is regulated.
  • However, sweat glands help in maintaining body temperature in humans.
  • There is no role of saliva in this case.

H) Regulation of water balances

  • Salivary secretions decrease when the content of body water decreases.
  • Thirst is thus induced as dryness of the mouth results.
  • Water after taken quenches the thirst.
  • This maintains the water level which gets stored again.

Salivary Glands - Definition, Function and Location | Biology Dictionary

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Functions of Saliva