The buccal cavity

• where does mechanical digestion begin?

  in the mouth/buccal cavity, where food is mixed with saliva by tongue and chewed with the teeth
• what happens to the food’s surface area in the mouth and what does this mean?

  the food’s surface area increases, giving enzymes more access
• what is saliva?

  its a watery secretion
• what does saliva contain?

  • amylase, beginning the digestion of starch and glycogen into maltose
  • HCO3$^-$and CO3$^{2-}$ions - the pH of the saliva varies between 6.2 and 7.4, although the optimum pH for salivary amylase is 6.7-7.0
  • mucus, lubricating the food’s passage down the oesophagus