2. Digestive processes in the mouth

2. Digestive processes in the mouth

1. functions of the mouth

   • ingestion
   • mastication
     • function
       • break food into small pieces
       • expose it to + surface area
     • 1st step in mechanical digestion
   • chemical digestion
     • saliva
       • functions
         • moistens mouth
         • starch digestion
         • inhibits bacterial growth
         • dissolves molecules (stimulate taste buds)
         • moistens food (forms bolus)
       • characteristics
         • pH: 6.8-7
         • hypotonic solution
           • 97-99.5% water
           • solutes
             • salivary amilase
             • lingual lipase
             • mucus
             • lysozyme
             • IgA
             • electrolytes (Na+,K+,Cl-,bicarbonate, phosphate)
       • by salivary glands
         • 2 types
           • intrinsic salivar glands (small, dispersed)
           • extrinsic salivary glands (1.5L, 3 pairs)
             • connected to oral cavity by ducts
             • parotid
             • submandibular
             • sublingual
         • histology
           • branched ducts ending in acini
           • mucus cells-mucus
           • serous cells-thin fluid (amylase and electrolytes)
           • mixed acinus (mucus and serous)
   • swallowing/deglutition
     • involves 22 muscles
     • 2 phases
       • buccal phase (voluntary)
       • pharyngoesophageal phase (involuntary

2. stratified squamous epithelium

3. related

   • pharynx
     • muscular funnel
     • connects oral cavity to esophagus
   • esophagus
     • straight muscular tube (25-30 cm)
     • deeply folded when empty

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