HUMAN ANATOMY AND PHYSIOLOGY

             Saliva::

It is the mixed secretion of all the glands in the oral cavity saliva contains inorganic salts sodium chloride potassium chloride and enzymes ptyalin (salivary amylase) phosphatase lipase and mucin the ph of salvia is usually netural or slightly acidic (6.0 to 7.0) 

fig transverse section of a salivary gland

functions of saliva::

1. Saliva keeps the mouth moist and facilitates speech 

2.Saliva helps in mastication of food and forms the bolus 

3.saliva dilutes hot and pungent substances and prevents injury to the mouth it also acts as a solvent soluble substances are dissolved and the taste buds appreciate the taste only when substances are in liquid state

 4.Saliva removes food particles and thus prevents the growth of microbes it also serves as an antiseptic to the mouth

 5.ptyalin present in saliva splits starch into maltose in the following order boiled starch soluble starch erythro dextrin and maltose achrodextrin and maltose iso maltose and finally maltose

 6.Maltase changes maltose into glucose to some extent so if one chews food well he enjoyes a sweet taste of glucose

 7.Saliva helps in excretion of heavy metals urea and certain other drugs 

8.Saliva helps in maintenance of water balance and is secreted through the nervous mechanism if saliva stops tongue becomes dry and man becomes thirsty

 9.saliva acts as a buffer by maintaining the level of bicarbonate and phosphate in the blood it changes the PH of blood so as to keep up the consistency of blood pH