Digestion in oral cavity

Common characteristic of the mouth cavity digestionCommon characteristic of the mouth cavity digestion In the oral cavity take place such main processes: In the oral cavity take place such main processes: 1. Primary analyses of substances, which are 1. Primary analyses of substances, which are

coming to organism – taste analyzes; coming to organism – taste analyzes; 2. Reflector signals from receptor, which are 2. Reflector signals from receptor, which are

present in these area to the another organs of present in these area to the another organs of digestive system, to the central nerve system – digestive system, to the central nerve system – medulla oblongata, stomach, small intestine, medulla oblongata, stomach, small intestine, pancreas; pancreas;

3. Chemical processing of food; 3. Chemical processing of food; 4. Mechanical processing of food; 4. Mechanical processing of food; 5. Absorption of some substances.5. Absorption of some substances.

Chewing of food is important, because Chewing of food is important, because fruits and vegetables have cellulose fruits and vegetables have cellulose which must be broken before the food which must be broken before the food can be utilized. In the mouth cavity can be utilized. In the mouth cavity begin digestion of carbohydrates, which begin digestion of carbohydrates, which help to the functional activity of help to the functional activity of pancreas. pancreas.

When our food are in the mouth stimulate the When our food are in the mouth stimulate the receptors of oral cavity; from which impulses receptors of oral cavity; from which impulses go to the different part of brain and return to go to the different part of brain and return to different part of digestion tract – stomach, different part of digestion tract – stomach, small intestine, pancreas, in which secreted small intestine, pancreas, in which secreted juices with enzymesjuices with enzymes

In the mouth cavity open three pair of big In the mouth cavity open three pair of big salivary glands and a lot of small buccal salivary glands and a lot of small buccal glands. Submandibular and sublingual glands. Submandibular and sublingual glands consist of the cells of serum and glands consist of the cells of serum and mucous types and secrete serous and mucus mucous types and secrete serous and mucus types of saliva. Parotid glands consist of the types of saliva. Parotid glands consist of the serum types cells and secrete serous type of serum types cells and secrete serous type of saliva. saliva.

Small buccal glands consist of mucous types Small buccal glands consist of mucous types of cells; produce mucous saliva with a big of cells; produce mucous saliva with a big quantity of water. Saliva necessary for our quantity of water. Saliva necessary for our digestion. In a mouth chewing a food by teeth digestion. In a mouth chewing a food by teeth and lingual. In the mouth cavity begin and lingual. In the mouth cavity begin digestion of carbohydrates by alfa-amilase – digestion of carbohydrates by alfa-amilase – ptyalin. To secrete different types of saliva for ptyalin. To secrete different types of saliva for digestion processes – with a big quantity of digestion processes – with a big quantity of water or organic and inorganic substances.water or organic and inorganic substances.

Quantity, composition and properties of Quantity, composition and properties of salivasaliva

Quantity, composition and properties of saliva (In the Quantity, composition and properties of saliva (In the case of dream produce nearly 0,05 mL/minute, in the case of dream produce nearly 0,05 mL/minute, in the normal condition – 0,5 mL/minute, in the case of normal condition – 0,5 mL/minute, in the case of maximal secretion – near 5 mL/minute. By day maximal secretion – near 5 mL/minute. By day produce 0,8-1,5 L of saliva. Composition of saliva: produce 0,8-1,5 L of saliva. Composition of saliva: water, organic – alfa-amilase, lipase, phosphatase, water, organic – alfa-amilase, lipase, phosphatase, RNAase, DNAase, mucin, substances for protective – RNAase, DNAase, mucin, substances for protective – lisocim, thiocianates, antibodies – and unorganic lisocim, thiocianates, antibodies – and unorganic substances – sodium, potassium, calcium, chlorites, substances – sodium, potassium, calcium, chlorites, etc.etc.

Mechanism of saliva formingMechanism of saliva forming In acinars' cells produce primary saliva in which In acinars' cells produce primary saliva in which

synthesis necessary amino acids, glucose, mineral synthesis necessary amino acids, glucose, mineral substances (for example, Casubstances (for example, Ca++++). In the cells of salivary ). In the cells of salivary glands occur passive processes, which provide glands occur passive processes, which provide moving of water and electrolits from blood to the moving of water and electrolits from blood to the glands’ ductus (strait). In the ductus occur glands’ ductus (strait). In the ductus occur reabsorption of sodium, chlorine, secretion of reabsorption of sodium, chlorine, secretion of potassium, HCOpotassium, HCO33

––. This is the secondary saliva. . This is the secondary saliva. Aldosterone increase reabsorption of sodium and Aldosterone increase reabsorption of sodium and secretion of potassium.secretion of potassium.

Role of saliva in vitality of Role of saliva in vitality of humanhuman

1. Moisten of solid food; 1. Moisten of solid food; 2. Dissolving of substances; 2. Dissolving of substances; 3. Moisten of mouth; 3. Moisten of mouth; 4. Cover food; 4. Cover food; 5. To help of swallowing; 5. To help of swallowing; 6. Primary hydrolyzing of carbohydrates; 6. Primary hydrolyzing of carbohydrates; 7. Antibacterial properties; 7. Antibacterial properties; 8. Neutralized the stomach juice.8. Neutralized the stomach juice.

Mechanism of saliva formationMechanism of saliva formation

Formation of salivaFormation of saliva Conditional reactions caused by appearance Conditional reactions caused by appearance

of food, it smell and other stimulus, which of food, it smell and other stimulus, which are connect with food.are connect with food.

Unconditional influences have parasympathetic and Unconditional influences have parasympathetic and sympathetic components. Parasympathetic sympathetic components. Parasympathetic components beginning from receptors of tongue components beginning from receptors of tongue and oral cavity. From its impulses pass through the and oral cavity. From its impulses pass through the fibers of n. trigeminus, n. facialis, n. vagus, n. fibers of n. trigeminus, n. facialis, n. vagus, n. glossopharyngeus, to the center of salivation. glossopharyngeus, to the center of salivation. Impulses return to saliva glands by n. facialis, n. Impulses return to saliva glands by n. facialis, n. glossopharyngeus. Sympathetic components of glossopharyngeus. Sympathetic components of unconditional influences beginning from side cornu unconditional influences beginning from side cornu of upper thoracic segments of spinal cord – Thof upper thoracic segments of spinal cord – Th22-Th-Th--

44. Then impulses go to saliva glands through the . Then impulses go to saliva glands through the upper cervix sympathetic ganglion. The cortex of upper cervix sympathetic ganglion. The cortex of big hemispheres, hypothalamus, lymbic system big hemispheres, hypothalamus, lymbic system regulate the salivation through these nerves. regulate the salivation through these nerves. Conditional signals, emotions may inhibit Conditional signals, emotions may inhibit salivation.salivation.

Influence of vegetative nerves on secretor Influence of vegetative nerves on secretor activity of salivary glandsactivity of salivary glands

Stimulation of the parasympathetic nerve Stimulation of the parasympathetic nerve supply causes profuse secretion of watery supply causes profuse secretion of watery saliva with a relatively low content of saliva with a relatively low content of organic material. Stimulation of the organic material. Stimulation of the sympathetic nerve supply causes profuse sympathetic nerve supply causes profuse secretion of saliva with small quantity of secretion of saliva with small quantity of water with a relatively big content of water with a relatively big content of organic material. organic material.

Mediator of parasympathetic nerve system – Mediator of parasympathetic nerve system – acetylcholine – stimulate M-cholinoreceptors of baso-acetylcholine – stimulate M-cholinoreceptors of baso-lateral membrane and activate entrance of Calateral membrane and activate entrance of Ca2+2+ and and activate kalmodulin. These reaction caused activate kalmodulin. These reaction caused production of a big quantity of saliva with low production of a big quantity of saliva with low quantity of organic substances. Mediator of quantity of organic substances. Mediator of sympathetic nerve system – norepinephrine – sympathetic nerve system – norepinephrine – stimulate adrenoreceptors of basolateral membrane, stimulate adrenoreceptors of basolateral membrane, activated adenilatcyclase that form cAMP. These activated adenilatcyclase that form cAMP. These reaction caused production of a small quantity of reaction caused production of a small quantity of saliva which have a big quantity of organic saliva which have a big quantity of organic substances.substances.

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