Questions for discussion.. Books recommended

Theme 6. (VC)

Digestive functions of the oral cavity: motor, secretion and absorption. Regulation of these functions. ( Variable course, VC)

Questions for discussion.

1. Motor acts of the mouth: chewing, swallowing, their regulation.

2. Secretion of saliva, regulation of secretion. The composition of the saliva of various salivary glands.

3. Functions of saliva.

Books recommended

1. Ganong W. F. Review of Medical Physiology. 20thed; McGraw-Hill Companies, Inc., 2001. – P.

2. Guyton A. C., Hall J. E. Textbook of Medical Physiology, 12thed; WB Saunders, 2008.

Practical work 1. Getting saliva of human.

For this work you need: capsule Lashley - Krasnogorsk, a syringe.

Technique. For getting mixed saliva the head leans forward, the saliva periodically spits out or, when the mouth opens, flows into a graduated vessel. You can get a clean saliva from the parotid ducts of the parotid glands with the help of the Lashley-Krasnogorsk capsule. On the inner surface of the cheek, at the level of the upper second molar tooth, the papilla of the excretory duct of the parotid gland is found. Apply the capsule to the papilla, so that the papilla is in the center of its inner chamber.

The tube leaving the outer chamber is connected to a syringe and air is sucked off by it. The capsule tightly adheres to the mucous membrane of the cheek. After sucking off air, a clamp is applied to the outgoing vacuum tube. Through the second tube, connected to the inner chamber, saliva flows into the tube. To separate the saliva, 1-2 teaspoons of citric acid are poured into the mouth.

Results. Record the amount of released saliva. Draw a Lashley – Krasnogorsk capsule.

Conclusions. What is the mechanism of salivation in the experiment?

Practical work 2. Recording and analysis of the masticaciogram in humans when chewing food products of varying degrees of hardness.

For this work you need: masticaciograph, a set of food products (bread, rusk, dragee, apple, etc. ).

Technique. The sensor of the masticaciograph, consisting of a rubber cuff enclosed in a flexible inextensible case, fix it on the lower jaw of the volunteer, then connect it to the recording device. Set the calibration of the instrument. Record several cycles of masticatory movements of the lower jaw (masticaciogram) when eating food of varying degrees of hardness: bread, breadcrumb, dragee, apple, etc. Use the recorded masticaciograms to analyze the duration of the phases, amplitude and frequency of chewing during the main chewing phase when chewing products of different hardness.

Results. Draw 2 masticaciograms: when chewing soft and hard products. Point the phases. Normal chewing phase consists of the following phases: 1 - rest phase, 2 – intake of food in the mouth, 3 - tentative chewing phase, 4 - the main phase of chewing, 5 - the formation of the food lump and the beginning of its ingestion. Calculate the duration of the phases, the number of masticatory movements in the main phase while taking food products of different hardness.

Conclusions. Indicate what the mechanism of the act of chewing, why the amplitude of chewing and the duration of the phases when chewing different products.

Practical work 3. Electromyogram of masticatory muscles recorded for different types of activities.

For this work you need: electromyography, electrodes.

Technique. Electrodes placed on the skin in the area projection of the main masticatory muscles, the EMG record.

Result: to compare the EMG with the continuous tension of the masticatory muscles, when making chewing movements.

Conclusion: to indicate the dependence of the EMG on various activities of the muscles.

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