Oral Cavity and Pharynx Prof. K. Sivapalan.

2013Oral Cavity and Pharynx2 Salivary Glands Parotid – Serous [25 %] Sub Maxillary – Mixed [70 %] Sub Lingual, Buccal – mucus. [5 %] Basal secretion – 0.25 ml / min, 1500 ml/day.

2013Oral Cavity and Pharynx3 Contents of Saliva pH- 7 at rest, 8 active secretion. Buffers: bicarbonate, phosphate, mucin. Enzymes: –Lingual lipase – glands on tongue. –Salivary amylase. Mucins [Glycoproteins] IgA. Lyzozyme Lactoferrin – binds Fe and bacteriostatic. Proline rich proteins – protect enamel and bind toxic substances. Na +, K +, Cl -, and HCO 3 - equal to plasma at high flow. Low Na + and high K + at rest. Exchange controlled by aldosteron.

2013Oral Cavity and Pharynx4 Functions of saliva. Moistening and Lubrication –speech, mastication, deglutition. Facilitating sense of Taste. Maintaining Oral hygiene –Lyzozyme, IgA, enzymes, flow. Protection of teeth – enzymes, pH, Ca. –[Causes of Dental caries.] Neutralization of gastric acid.

2013Oral Cavity and Pharynx5 Control of Salivary Secretion. Stimuli: –Higher centers [thought, sight, smell- conditioned reflex] –Touch- smooth objects [most] –Taste- bitter [most] –Stomach- irritation Afferents Centre- salivary nucleus. Efferent- Parasympathetic. Sympathetic activity- inhibition [dry mouth in excitement]

2013Oral Cavity and Pharynx6 Mastication Force at the incisors is 55 pounds and molars is 200 pounds. Purpose: increase surface area for enzyme action and facilitate movement through GIT [differences between processed and naturally occurring food] Voluntary action but Chewing reflex occurs. Chewing movements can be produced by stimulating: –Reticular formation of hind brain –Hypothalamus –Amygdaloid nuclei –Cerebral cortex near area for taste and smell

2013Oral Cavity and Pharynx7

2013Oral Cavity and Pharynx8

2013Oral Cavity and Pharynx9

2013Oral Cavity and Pharynx10 Deglutition Voluntary Stage – food pressed against pharynx Pharyngeal stage –Afferents[5,9,10 CN] to deglutition centre, Efferents [5,9,10,12] –Soft palate- close nasopharynx –Palato-pharyngial folds- slit –Larynx pulled up, vocal cord close, epiglottis fold back. –pharyngeal muscles initiate peristalsis –Upper and lower esophageal sphincters relax Food falls due to gravity before peristalsis reaches stomach when erect.