Pain. Nociceptive system. Anti-nociceptive system

Theme 3.

Pain. Nociceptive system. Anti-nociceptive system

Sensory function of the oral cavity. Olfactory sensory system. Taste sensory system.

The goal of lesson is studying organization noci- and anti-nociceptive systems, sensory function of oral cavity.

Questions for discussion

1. A taste sensory system. Receptor department of the taste system. Determination method. A taste receptors, their kinds. Functional mobility.

2. Olfactory sensory system. Odor classification. Interaction of taste and olfactory sensory systems.

3. Nociceptive system, its departments. Nociceptors.

4. Antinociceptive system, its levels, neurophysiological mechanisms.

5. Physiological basis of anesthesia in dentistry.

6. Skin sensory system:

А) tactile sensitivity, types of receptors, spatial thresholds of sensitivity.

B) temperature sensitivity, classification of thermoreceptors

Books recommended

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

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

Practical work 1. Study of pain points.

For this work you need: pins or wooden disposable toothpicks.

Technique: Draw a square size of 10 × 10 mm on the hair surface of the forearm. Touch the skin inside the square sequentially by the point of the sterile pin, making 10 touches horizontally in 10 lines along the vertical line, i.e. passing each mm of the square. Pressures are of the same strength, 100 touches at all. The time interval between touches is 1-2 s. Describe the sensations of the volunteer. When touching different points of the skin, the volunteer may experience sensations of touch, blunt or severe pain. Conduct the study on the volunteers of different sexes.

Results. The subject experiences different sensations: sometimes pressure, and sometimes pain.

Conclusions. Convinced of the existence of pain points on the skin

Practical work 2. Research of taste fields of the tongue.

For this work you need: 40% glucose solution, 2% citric acid solution, 20% sodium chloride solution, 1% quinine hydrochloric acid solution, glass sticks, distilled water.

Technique: The volunteer rinses his mouth and puts out his tongue, and the researcher, after moistening the tip of the glass rod first in a sweet solution, and then in an acidic, salty, bitter solution, consistently touches the tip, the middle part, the side surfaces and the root of the tongue. The interval between individual exposures should not be less than two minutes. The volunteer reports on the feelings that have arisen. After each test, rinse the mouth with distilled water.

Results. Draw the topography of the taste sensitivity of the language.

Conclusions. Estimate the role of taste sensitivity in digestion.

esults. Write the results into the table.

Practical work 3. Identification of tactile thresholds on the skin of the face, fingers and forearm.

For this work you need: Weber's compass, ruler.

Technique: treat Weber compasses with alcohol, apply compass legs to different skin areas, push them apart until you feel the touch of two objects, measure the distance between compass legs, this will be the threshold of tactile sensitivity.

Results. skin of the face fingertips forearm

Conclusion. The difference in thresholds is explained by the different density of tactile receptors, it is maximal on the fingers, on the forearms very low.

Temperature map of the oral cavity. Temperature reception: cold receptors (Krause flasks) are more located in the anterior oral cavity, thermal (Ruffini bodies) - in the rear. Mucous cheeks insensitive to cold and heat. The hard palate does not perceive heat, and the root of the tongue neither heat nor cold; however, the tip of the tongue and the rim of the lips are very sensitive to temperature stimuli. Temperature above 54o - pain in the mouth. Teeth: at the incisors of the cold threshold - 20o, the rest - 11o; thermal threshold for incisors -52o, for the rest - 60-70o.

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