Mechanisms for regulation of saliva secretion

- Influence of local incitement

The food mechanically irritates the surface of glandular cells and causes saliva secretion. The presence of smooth objects in oral cavity (e.g. pebble) results in substantial hypersalivation while rough objects cause weaker salivation and maybe even stop it.

Chemical irritation, specially the taste of sour, results in abundant hypersalivation, often as high as 5 ml per minute or 8 to 20 times more than the basal saliva secretion.

Nervous regulation of saliva secretion

Submandibular and subligual glands are controlled by neural impulses from upper salivary nucleuses and parotid gland by impulses from lower salivary nucleuses. Those nucleuses are situated close to the border of medulla oblongata and pons and they are stimulated by receptors for taste and touch of the tongue and other areas of oral cavity.

Salivation can be stimulated or inhibited by impulses coming to salivation centers from higher centers of the central nervous system. For example, salivation intensifies when someone smells or eats the food he likes. The center for appetite in the brain regulating this is located very close to parasymphatic nucleuses in frontal hypothalamus and activity of that area is to a large extent a reaction to impulses coming from the center for taste and smell, located in almond nucleuses in cortex.

The role of autonomous nervous system - parasymphatic stimulation

Stimulation of parasymphatic nearly always intensifies gland secretion. Stimulation of symphaticus, by itself, has a slight effect on secretion. However, weak parasymphatic stimulation often results in reduced secretion due to vasoconstriction and poorer blood supply.

Hormonal regulation of salivation

Certain hormones, above all aldosteron, estrogen and progesterone, play an important role in salivation and composition of saliva .

Excessive secretion of aldosteron brings about increased reabsorption of Na and Cl while the secretion of K increases; thus, the concentration of NaCl in saliva is reduced and the concentration of K is increased.

Stimulation by estrogens intensifies the secretion of saliva with the larger quantity of water, Na and Cl. Increased concentration of NaCl in saliva leads to its crystallization. Progesterone causes decrease in quantity of saliva, its water share and concentration of Na and Cl.