Saliva and gastric secretions

• digestion • protection • lubrication • antibacterial roles • blood clotting • calcification of teeth

• amylase cleaves the 1,4-glycosidic bonds • lingual lipase hydrolyses lipids

• it prevents drying of the oral cavity (drying causes weakening of the oral tissue)

• its involved in the swallowing of bolus

• lactoferrin chelates iron as a lot of bacteria require iron to survive • lysozymes are involved in the degradation of bacterial cell walls • it contains immunoglobulins

• prevents gum disease • promotes wound healing

• acids from food decalcify the teeth and so calcium phosphates and phosphoproteins buffer these acids

• parotid glands • submaxillary glands • sublingual glands

• secretes 25% of saliva • serous and watery secretion

• secretes 70% of saliva • serous and mucous secretion

• predominantly mucous secretion

• xerostomia • Sjogren’s syndrome • hyperaldosteronism

• significant reduction or absence of saliva • leads to a decrease in chewing, swallowing and digesting • caused by some medications, congenital diseases and cranial nerve damage

• autoimmune inflammatory disease • blocked ducts causes atrophy of glands

• can be primary or secondary • increase in aldosterone secretion • causes include hypertension and hypokalaemia

• low potassium in the blood • impacts the sodium content of the saliva

• basal secretion : happening continuously • stimulated secretion : increase in secretion upon stimulation of the salivary glands

0.5 - 7 ml/min

• regulation of salivary secretion is controlled by the autonomic nervous system • sensory receptors relay information to salivatory nuclei in the medulla

• promotes watery saliva • rich in amylase and mucins

• has a variable effect • can increase or inhibit secretion of saliva

1) parasympathetic stimulation will bring in chloride ions into the acinar cells through a cotransporter protein 2) sodium ions and potassium ions will also move into the cells via the cotransporter 3) chloride ions are pumped out of the cell into the acinus region and this makes the acinus region have a slightly negative potential 4) this negative potential drives the movement of water and sodium ions into the acinus region through paracellular channels 5) sodium ions are pumped out of the acinar cells in exchange for potassium ions so sodium ions can move paracellularly 6) potassium ions are pumped out of the acinar cells so they can come in with chloride ions or in exchange for sodium ions

movement between cells

• the ducts are relatively impermeable to water and this allows saliva to change from isotonic to hypotonic • the removal of chloride ions and sodium ions will change the saliva from isotonic to hypotonic