QS Study

Regulation of Saliva Secretion

The production of saliva in conscious humans is under the organization of the higher centers of the brain which is unregulated by an autonomic reflex in reaction to tasting, chewing, and smell. An understanding of this multifarious control of salivary secretion is mainly significant for the restoration of the salivary glands and their functions. Reflex salivary flow occurs at a low ‘resting’ rate and for short periods of the day more intense taste or chewing stimuli evoke up to ten-fold increases in salivation.

Control of Saliva Secretion

(A) Neural Control

Saliva Secretion is under neural control. The primary physiological control of salivary glands is by the parasympathetic nervous system, (Parasympathetic nervous signal from superior and inferior salivatory nuclei in the brain stem)

Fig: Parasympathetic nervous regulation Salivary Secretion

  1. Conditioned/acquired reflex.
  2. Unconditioned or inherent or inborn reflexes.

Conditioned reflex

(a) Salivation occurs in absence of food such as sight, vision and smell stimulate saliva secretion reflex although no food is actually given in mouth.

(b) Favorite food →↑ Salivation

(b) Unconditioned reflex

(a) Here salivation occurs in presence of food in the mouth cavity. Parasympathetic (mainly) and sympathetic nervous system regulates the saliva secretion by a nervous signal.

(b) Salivation also occurs in response to reflexes, originating in the stomach and upper intestine -particularly when irritating foods err swallowed. Amount of secretion depends on the type of Food. Some drugs like a cholinergic drug like e.g., Acetylcholine and Atropine have an effect on saliva secretion.

(B) Secondary control

A Secondary factor that also affects secretion is the blood supply to the glands because secretion always requires adequate nutrition.

Fig: Formation and Secretion of saliva by submandibular salivary glands