Irritation of the mouth or reject food substances, as well as irritation of the nasal cavity is unconditional, salivation innate reflexes.
Afferent impulses are transmitted to the central nervous system receptors of the oral cavity by lingual (branch of the trigeminal) and glossopharyngeal nerves of receptors shed – by the upper pharyngeal branch of the vagus nerve, and the receptors of the nasal cavity – on the branches of the trigeminal nerve. Salivation reflex also occurs during stimulation of many afferent nerves is horny cavity.
Each salivary gland efferent impulses are transmitted in two nerves: parasympathetic and sympathetic.
The parasympathetic fibers to the submandibular and sublingual glands are sent as part of tympani. (7th pair of cranial nerves), which, in addition to efferent vasodilator and secretory fibers to these glands, and the language has more glands afferent fibers and fibers that carry impulses from the taste receptors.
Parasympathetic fibers to the parotid gland are composed glossopharyngeal nerve (9th pair), which contains secretory and vasodilating the afferent fibers.
If you insert the cannula into the salivary meek, combine it with a pressure gauge to measure the pressure in the excretory ducts of the salivary gland during stimulation tympani, it will appear that it can almost 2 times higher than normal blood pressure measured in the carotid artery. Saliva secretion occurs during stimulation of nerves and arteries after tying that carry blood to the glands, and the fresh corpse. Consequently, when nerve stimulation does not occur secretory filtration and secretion of saliva.
Supply of blood cancer during stimulation tympani increases by 4-5 times, and with stimulation of the sympathetic nerve is reduced by 3-4 times.
Irritation tympani causes a lot of salivation containing a significant amount of salts and relatively little organic matter.
P. Vvedenskii back in 1893 found that stimulation of the parasympathetic nerves, salivary gland with increasing frequency and strength of stimulation gives a decrease in salivation (pessimum).
It was found that during stimulation tympani turn acetylcholine or acetylcholine like substance which enters the bloodstream and have an effect of nervous and humoral way.
Another secretory nerve, besides containing secretory vasoconstrictor efferent and inhibitory fibers are cervical sympathetic nerve. Its fibers originate from II-VI thoracic segments of the spinal cord and terminated in the upper cervical sympathetic node. Stimulation of the sympathetic nerve causes a slight salivation, but the organic substances in the saliva significantly more salts downward.
The nerve endings of the sympathetic nerves stand out adrenaline and noradrenaline. In humans, the sympathetic nerves induce salivation only from submandibular glands and do not act on the parotid gland.
Subcortical centers salivation are afferent and efferent parts of the nuclei of cranial nerves in salivary medulla. The medulla neurons salivating arranged in the reticular formation, and an intermediate – in the hypothalamic region. The centers in the medulla oblongata salivation excited first, inflow pulse along nerve pathways and, secondly, through the blood changing its composition. For example, if choking carbon dioxide accumulates in the blood, stimulates salivation center, accompanied by a large number of secretion of saliva. After transection of secretory parasympathetic nerves saliva decreases sharply.
The excitability of the center of the salivary glands varies with different composition of blood hungry and well-fed animal: it increases during starvation, while the well-fed animal is reduced. Salivation cause pituitary hormones, sex, pancreas and thyroid glands.
Higher Center of salivation is in the anterior cortex (VMBekhterev and NA Mislavsky, 1888). Removing the center reduces the amount of salivary conditioned reflexes (OS Andrianov, 1963).
A wide variety of irritation of the mucous membranes of the mouth (chemical, thermal, mechanical and painful) reflex stimulates the salivary glands.
The action of chemical stimuli most strongly with the root of the tongue, with the tip of the tongue is weaker and weaker from its lower surface. Bitter and salty substances cause salivation in most cases, only root of the tongue.
In experiments conducted on people found that the taste of some receptors causes irritation, salivation and – stimulation of other receptors.
After turning off a man of taste sensations action of cocaine on receptors salivation reflex irritation persists flavorings.
There are reflections on the salivary gland of the stomach and intestines, regulating the secretion of saliva during digestion. It was found that the salivary glands of the higher nerve centers by pulses of afferent nerves. The physiological significance of these pulses is that due to their influx into higher nerve centers reflexively adjust the level of activity of the salivary glands efferent nerves (SI Halperin, 1936). This reflex own cancer.
Reflex salivation at mechanical, thermal and chemical irritation of the mouth food is innate, unconditional.
The sight and smell of food come rejected substances, and sounds associated with their appearance, are irritants that cause reflex salivation, after this the food or reject material previously introduced into the oral cavity (SG Wolfson, 1898 I. Tsitovich, 1911).
Conditioned and unconditioned reflexes determine compliance with the progress of salivation as well as the quantity and quality of saliva mind the smell, the quality and quantity of food and the course of its machining in the mouth.