Theme 1 - Part IV Flashcards
Function of saliva
Lubrication - moisten, tongue movement and taste receptor presentation
Protection - alkalinity, wash away and additional substances
Digestion - alpha amylase and lingual lipase
Alpha amylase
hydrolyzes starches. It has a pH optimum of 7
α-Amylase can break down up to 75% of the starch in a meal before the enzyme is denatured by gastric acid.
Lingual lipase
hydrolyzes triglycerides and is secreted by the small salivary glands present on the surface of the tongue. It has an acidic pH optimum and remains active in the stomach.
Sjögren’s syndrome [3]
autoimmune disease that destroys the exocrine glands and most commonly affects tear and saliva production.
sicca symptoms.
Patients with xerostomia
Salivary gland types [3]
The submandibular glands secrete approximately 70% of saliva (mixed).
The parotid glands secrete 25% (serous).
The sublingual glands secrete 5% (mucus).
Acinar cell
Secrete primary saliva - isotonic (interstitial)
Reabsorb NaCl = hypotonic
Cl: Basolateral NaKCC and apical
Na: paracellualry - LTJ
Ductal cell
Na: Removal via apical channel and Na/K ATPase
Cl: Apical and basolateral
Secrete bicarbonate and potassium via apical bicarbonate chloride & potassium proton exchanger
Central control of salivary secretions
Stimuli are integrated by the salivary nuclei in the pons, and salivation is determined by the resulting parasympathetic tone.
Efferent nerves reach the salivary glands via the glossopharyngeal and facial nerves. Acinar secretion is stimulated by the release of acetylcholine, which acts via the muscarinic receptors.
Parasympathetics stimulation
- promote watery secretion myoepithelial cells surrounding acini and ducts contract and eject preformed saliva
- also leads to increased blood flow
Sympathetics stimulation
- does increase output of amylase but …
- blood flow reduced (vasoconstriction) and fall in rate of secretion e.g. in dry mouth associated with fear
