School of Dentistry, Tongji University Oral physiology Oral Function ZHANG LEI School of Dentistry, Tongji University

Swallowing Swallowing: move food and liquid from the mouth to the stomach; a very complex reflex process.

Process of swallowing I. Oral preparatory phase: the food is chewed and mixed with saliva to form a moist, cohesive bolus ready to be swallowed. II. Pharyngeal phase: When the food bolus comes into contact with the mucosa of the pharynx and larynx , it activates mucosal mechanoreceptors, hence activate many muscles that are involved in swallowing. The next event in this complex sequence of events is the inhibition of respiration. III. Oesophageal phase: Once in the oesophagus, the food bolus is propelled towards the stomach by peristalsis (partly controlled by the vagus nerve)

Speech Speech denote the peripheral processes that are needed to produce spoken language, it is a motor activity and consequently can be mapped onto anatomical structures of the articulatory tract.

Functional subsystems of motor speech I. Respiration: II. Phonation (sound production): III. Resonance: IV. Articulation:

Saliva Saliva glands: Parotid gland: 22-30% Submandibular gland: 60-65% Sublingual gland: 2-4% Minor glands: 7-8%

Composition of saliva Daily production: 1-1.5 L (0.5 ml/min) Density: 1-1.009 pH: 6-7.9 (6.75) Water: 99.4% Inorganic: 0.2% Organic: 0.4%

Inorganic saliva composition

Organic saliva composition Proteins: 1) Digestive enzymes: α-amylase: hydrolyses the α-1,4 glycosidic linkages of starch molecules Lipase: an enzyme able to break down dietary triglycerides. 2) Proteins with lubricating functions: Mucins(粘蛋白) 3) Calcium binding proteins: statherin（富酪蛋白） 4) Carbon dioxide hydration: Carbonic anhydrase: catalyse the reversible hydration of CO2. to carbonic acid. 5) Saliva proteins with antimicrobial functions: secretory IgA (sIgA), mucins, lysozyme and lactoferrin（乳铁蛋白）. 6) Growth factors in saliva: epidermal growth factor (EGF) , Transforming growth factors (TGF-a and TGF-P) , fibroblast growth factor (FGF)

Saliva functions

Saliva functions Saliva buffer capacity The ability of the saliva to maintain the pH when exposed to acids is termed buffer capacity. Buffer systems in saliva: 1. The bicarbonate buffer system CA CA CO2+H2O H2CO3 HO3- + H+ 2. The phosphate buffer system

Sensation:taste All animals including humans respond to chemical stimuli through specialized chemosensory systems such as taste and smell.

Sensation:taste Taste papillae in humans come in at least 4 different shapes and are located on the tongue, soft and hard palate, pharynx, epiglottis and larynx.

Sensation:taste Sensibility of different portions of the tongue varies: Top: more sensible to sweet Lateral: sour Base: bitter Palate: sour, bitter

Pain Thermal sensation Other sensations Pain Thermal sensation

“…with the changing patterns of dental practice consequent upon the declining prevalence of dental caries, the more complex needs and expectations of the patient will hinge upon a much greater knowledge of oral physiology.” C.L.B. Lavelle