Saliva is secreted from salivary glands. Lalars contains 95.5% water and 0.5% electrolytes and protein. A person secretes 1200-1500 ml of saliva every day. When the secretion of saliva is reduced, the lips become dry, a condition known as xerostomia.
(i) Taste: Saliva helps the tongue to taste. People with low salivation suffer from dysgeusia.
(ii) Softening and liquefying of food: Mucin in saliva softens and liquefies the food.
(iii) Destruction of microbes: Lysozyme destroys bacteria or microbes.
(iv) Food digestion: Tylin and maltase enzymes digest sugary food.
(v) Dehydration: When the body becomes dehydrated, salivary secretion decreases and thirst is felt. Water balance is maintained by drinking water.
(vi) As a buffer: Mucin present in saliva, bicarbonate and phosphate act as buffers.
(vii) Excretion: Urea, heavy metals, thiocyanate, antibiotics, morphine, ethyl alcohol etc. are excreted from the body through saliva.