Excitation of the respiratory center by carbon dioxide. Respiratory center, its localization, structure and regulation of activity
Baseline knowledge
1. What is the respiratory center?
2. Why does inhalation occur?
3. Why does exhalation occur?
4. Why does breathing quicken during excitement, running?
5. Why is it necessary to regulate breathing?
| The student must know: 1. Respiratory center. Functional characteristics center neurons. Mechanism of change of respiratory phases. 2. The role of lung mechanoreceptors, afferent fibers of the vagus nerve in the regulation of respiration. Hering-Breuer reflexes. 3. Humoral regulation breathing. Frederick's experience. 4. Reflex regulation breathing. Gaimans experience. 5. Central influences on breathing from the hypothalamus, limbic system, cerebral cortex. 6. Breathing as a component of various functional systems. Profile questions for the pediatric faculty: 7. Causes and mechanism of the first breath. 8. Features of the regulation of breathing in children. 9. Formation of voluntary regulation of respiration in ontogeny. The student must be able to: Explain the mechanism of activation of respiration during physical activity. | Main literature: 1. Fundamentals of human physiology. Ed. Tkachenko B.I. / M. Medicine, 1994. - v.1. -p.340-54. 2. Fundamentals of human physiology. -p.174-6. 3. Fundamentals of human physiology. Ed. Tkachenko B.I. / M. Medicine, 1998. - v.3. -p.150-75. 4. Human physiology. Ed. Schmidt R.F. and Thevsa G. Transl. from English. / M. "Mir", 1986. - v.1. -p.216-26. 5. Normal human physiology. Ed. Tkachenko B.I. / M. Medicine, 2005. -p. 469-74. 6. Human physiology. Compendium. Ed. Tkachenko B.I. / M. Medicine, 2009. -p.223-32. 7-9. Physiology of the fetus and children. Ed. Glebovsky V.D. / M., Medicine, 1988. -p.60-77. Additional literature: The beginnings of physiology. Ed. A. Nozdracheva / St. Petersburg, "Lan", 2001. Kazakov V.N., Lekakh V.A., Tarapata N.I. Physiology in tasks / Rostov-on-Don, "Phoenix", 1996. Perov Yu.M., Fedunova L.V. Well normal physiology of man and animals in questions and answers. / Tutorial for self-study. Krasnodar, publishing house of the Kuban State Medical Academy. 1996. part 1. · Grippy M. Pathophysiology of the lungs. Per. from English. Ed. Natochina Yu.V. 2000. Lung auscultation. Guidelines for foreign students. Minsk, 1999. |
Task for work:
No. 1. Answer the questions:
1. How will breathing change when mild poisoning carbon monoxide?
2. Why does breathing intensify immediately with sudden movements, and with a delay - only after a while?
3. What is the difference between central and peripheral chemoreceptors?
4. What is the Euler-Liljestrand effect?
5. If, holding your breath, make swallowing movements, then you can significantly increase the delay time. Why?
6. It is known that in case of carbon monoxide poisoning ethnoscience advises the victim to lay on the floor, preferably lowering his face into a shallow hole. If you take it to Fresh air, then death may occur. Why?
7. How will breathing change in a person after a tracheostomy (artificial communication of the trachea with the atmosphere through a tube on the front surface of the neck)?
8. The midwife claims the baby was stillborn. How can one absolutely prove or disprove this assertion?
9. Why can emotional excitement increase and speed up breathing?
10. In resuscitation practice, carbogen is used (a mixture of 93-95% O 2 and 5-7% CO 2). Why is such a mixture more effective than pure oxygen?
11. A person, after several forced deep breaths, became dizzy and turned pale sharply. skin faces. What are these phenomena related to?
12. When inhaling irritants such as ammonia, tobacco smoke there is a reflex stop of breathing. How to prove that this reflex occurs from the receptors of the upper mucosa respiratory tract?
13. With pulmonary emphysema, elastic recoil is disturbed, and the lungs do not collapse enough on exhalation. Why is the breathing of a person suffering from emphysema shallow?
14. In case of violation excretory function kidneys (uremia) there is a large noisy breathing, i.e. a sharp increase in ventilation of the lungs. Why is this happening? Can this be considered an adaptation?
15. As a result of poisoning with mushroom hemolytic poison, a person developed shortness of breath. What is its reason?
16. How will the dog's breathing change after bilateral transection of the vagus nerves?
No. 2. Solve the problem:
Under conditions of relative rest with normal ventilation and perfusion of the lungs, every 100 ml of blood passing through the lungs absorbs about 5 ml of O 2 and releases about 4 ml of CO 2 . Subjects at minute volume breath of 7 liters was absorbed in 1 min. 250 ml O 2 .
How many ml of blood passed through the capillaries of the lungs during this time and how much CO 2 was released?
No. 3. Picture:
· scheme of organization of the central apparatus of regulation of respiration; levels of breathing regulation;
· Frederick's experience;
Geimans experience.
No. 4. Continue definition: the respiratory center is...
Hering-Bretser reflexes are...
No. 5. Test tasks:
1. The change of inhalation with exhalation is due to: A) the activity of the pneumotaxic center of the pons; C) activation of inspiratory neurons of the respiratory center of the medulla oblongata; C) irritation of the juxtacapillary receptors of the lungs; D) irritation of irritant receptors of the mucous membrane of bronchioles.
2. What is the Hering-Breuer reflex: A) reflex excitation of the inspiratory center during irritation of pain receptors; C) reflex excitation of the inspiratory center during the accumulation of excess CO 2, C) reflex inhibition of the inhalation center and excitation of the exhalation center during lung stretching; D) the appearance of the first breath of the newborn.
3. Which of the following provides the appearance of the first breath of a newborn child: A) excitation of the respiratory center due to the accumulation of CO 2 in the child's blood after cutting the umbilical cord; B) braking reticular formation brainstem in case of irritation of skin receptors (thermo, mechano, pain) of a newborn; C) hypothermia; D) clearing the airways of fluid and mucus.
4. What structures of the CNS can be attributed to the concept of "respiratory center": A) hypothalamus; C) subcortical or basal nuclei; C) nuclei of the midbrain; D) pituitary.
5. How does the automatism of the respiratory center differ from the automatism of the pacemaker of the heart?: A) practically does not differ; B) the respiratory center does not have automatism; C) the automatism of the respiratory center is under pronounced voluntary control, but the automatism of the pacemaker of the heart is not; D) the automatism of the respiratory center is under the control of the pacemaker of the heart, and there is no feedback.
6. Where should tonic signals come from to the respiratory center to ensure its automatism?: A) such signals are not needed; B) from "jay" receptors; C) from the cerebral cortex; D) from mechano-, chemoreceptors and reticular formation.
7. What was established by Frederick in 1890 in experiments on dogs with cross-circulation?: A) the respiratory center is located in the medulla oblongata; B) the respiratory center consists of inspiratory and expiratory sections; C) the activity of the respiratory center depends on the composition of the blood entering the brain; D) when the vagus nerve is stimulated, the respiratory rate increases.
8. How does irritation of parasympathetic nerves affect the sensitivity of chemoreceptors of the respiratory system?: A) no effect; B) raises; C) lowers; D) central - lowers, peripheral - increases.
9. What is Head's paradoxical effect?: A) long breaths during transection of the vagus nerves; B) convulsive breath with strong inflation of the lungs; C) short breaths and long expiratory pauses during transection of the brain between the medulla oblongata and the bridge; D) periodic increase to a maximum and decrease to apnea in the depth of breathing.
10. Why do central chemoreceptors react to changes in blood gas composition later than other chemoreceptors?: A) because their irritation threshold is the highest; B) because there are very few of them; C) because they are simultaneously mechanoreceptors; D) because it takes time for the penetration of gases from the blood into the cerebrospinal fluid.
11. What neurons of the respiratory center are excited under the influence of impulses from the central chemoreceptors?: A) central chemoreceptors do not directly affect the respiratory center; B) inspiratory and expiratory; C) only expiratory; D) only inspiratory.
12. Which of the following causes irritation of irritant receptors?: A) dust, smoke, cold air, histamine, etc.; B) accumulation of fluid in the lung tissue; C) accumulation of hydrogen ions in the cerebrospinal fluid; D) hypercapnia.
13. What respiratory receptors are irritated with burning and itching sensations?: A) "jay" - receptors; B) mechanoreceptors of the intercostal muscles; C) irritant; D) aortic chemoreceptors.
14. What is the sequence of the listed processes during coughing?: A) deep breath, divergence vocal cords, closure of the vocal cords, contraction of the expiratory muscles; B) deep breath, closure of the vocal cords, contraction of the expiratory muscles, divergence of the vocal cords; C) contraction of the expiratory muscles, closure of the vocal cords, deep breath, divergence of the vocal cords; D) closure of the vocal cords, contraction of the expiratory muscles, deep breath, divergence of the vocal cords.
15. What is the sequence of the listed processes during sneezing?: A) closure of the vocal cords, contraction of the expiratory muscles, deep inspiration, divergence of the vocal cords; B) deep breath, divergence of the vocal cords, closure of the vocal cords, contraction of the expiratory muscles; C) contraction of the expiratory muscles, closure of the vocal cords, deep inspiration, divergence of the vocal cords; D) deep breath, closure of the vocal cords, contraction of the expiratory muscles, divergence of the vocal cords.
16. What is physiological significance tachypnea with an increase in body temperature?: A) ventilation of the alveoli improves; B) ventilation of the “dead” space increases, which enhances heat transfer; C) alveolar perfusion improves; D) interpleural pressure decreases.
17. What is apneisis?: A) convulsive inspiration with strong inflation of the lungs; B) short breaths and long expiratory pauses during transection of the brain between the medulla oblongata and the bridge; C) deep long breaths during transection of the vagus nerves and simultaneous destruction of the pneumotaxic center; D) periodic increase to a maximum and decrease to apnea in the depth of breathing.
18. What is gasping breathing?: A) short breaths and long expiratory pauses when the brain is cut between the medulla oblongata and the pons; B) periodic increase to a maximum and decrease to apnea in the depth of breathing; C) long breaths during transection of the vagus nerves; D) convulsive inspiration with strong inflation of the lungs.
19. Which of the following types of pathological respiration is periodic?: A) Biot's respiration; B) Cheyne-Stokes breathing; C) wavelike breathing; D) all of the above.
20. What is undulating breathing?: A) short breaths and long expiratory pauses when the brain is transected between the medulla oblongata and the pons; B) convulsive breath with strong inflation of the lungs; C) long breaths during transection of the vagus nerves; D) periodic increase and decrease in the depth of breathing.
21. What is Cheyne-Stokes breathing?: A) prolonged breaths during transection of the vagus nerves; B) suddenly appearing and suddenly disappearing respiratory movements of large amplitude; C) convulsive breath with strong inflation of the lungs; D) periodic increase to a maximum and decrease to apnea. lasting 5 - 20 s, the depth of breathing.
22. When is Cheyne-Stokes respiration observed?: A) in severe physical work; B) with altitude sickness, in premature babies; C) with neuropsychic stress; D) when clamping the trachea.
23. What is Biot's breathing?: A) alternation of rhythmic respiratory movements and long (up to 30 seconds) pauses; B) periodic increase to a maximum and decrease to apnea, lasting 5-20 s, in the depth of breathing; C) short breaths and long expiratory pauses during transection of the brain between the medulla oblongata and the bridge; D) convulsive inspiration with strong inflation of the lungs.
24. Which of the following is used for artificial respiration?: A) periodic injection of air into the lungs through the airways; B) periodic irritation of the phrenic nerves; C) rhythmic expansion and contraction chest; D) all of the above.
25. What is asphyxia?: A) low content of hemoglobin in the blood; B) inability of hemoglobin to bind oxygen; C) suffocation; D) irregular breathing.
26. Asphyxia: A) hypoxia and hypocapnia occur; B) hypoxemia occurs, and the carbon dioxide content does not change; C) hypoxia and hypercapnia occur; D) hypocapnia and hyperoxia occur.
27. What is the function of the pneumotaxic center?: A) regulation of the alternation of inhalation and exhalation and the size of the tidal volume; B) regulation of airflow in the respiratory tract during speech, singing, etc.; C) synchronization of the activity of the right and left halves of the respiratory center; D) generation of the respiratory rhythm.
28. Does gasping occur spontaneously in non-operated animals and humans?: A) no; B) occurs only in animals that run away from an attack; C) regularly occurs in a dream; D) occurs in terminal states.
29. How does breathing change if you breathe pure oxygen?: A) the respiratory center is overexcited; B) breathing slows down to apnea; C) becomes deep and superficial; D) cerebral hypoxia occurs.
30. What is carbogen?: A) a mixture of gases used by divers; B) a mixture of gases used for breathing at high altitudes; C) a mixture of oxygen and carbon dioxide 1:4; D) a mixture of 95% oxygen and 5% carbon dioxide for patients with hypoxia.
31. What is the mechanism of the first breath of a newborn?: A) excitation of the respiratory center in response to pain; B) excitation of the respiratory center in response to the inhalation of oxygen atmospheric air; C) excitation of the respiratory center in response to hypercapnia and irritation of the reticular formation; D) inflation of the lungs as a result of a cry.
32. At what period of intrauterine life is the fetus able to breathe?: A) 2 months; B) 6 months; C) 12 weeks; D) not earlier than 7 months.
33. How does breathing change when the vagus nerve is stimulated?: A) it becomes deep; B) is becoming more frequent; C) is being reduced; D) sleep apnea occurs.
34. How does breathing change when the vagus nerve is cut?: A) it becomes deep and frequent; B) is becoming more frequent; C) dyspnea occurs; D) becomes deep and rare.
35. How does irritation of the vagus nerve affect the bronchi?: A) causes bronchospasm and, as a result, dyspnea; B) narrows the lumen; C) expands the lumen; D) has no effect, because nervus vagus does not innervate the bronchi.
36. How does stimulation of the sympathetic nerve affect the bronchi?: A) expands the lumen; B) causes bronchospasm and consequently suffocation; C) does not affect, since the sympathetic nerve does not innervate the bronchi; D) narrows the lumen.
37. What is a "diver's reflex"?: A) deepening of breathing after immersion in water; B) hyperventilation of the lungs before immersion in water; C) apnea when exposed to water on the receptors of the lower nasal passages; D) apnea when swallowing water.
38. What influence does the cerebral cortex have on the respiratory center at rest?: A) it practically does not; B) brake; C) exciting; D) excitatory in children, inhibitory in adults.
39. When does altitude sickness occur?: A) when climbing to a height of at least 10 km; B) when climbing to a height of more than 1 km; C) when climbing to a height of 4 - 5 km; D) when moving from an area of high to an area of normal atmospheric pressure.
40. How does respiration change under reduced atmospheric pressure?: A) first it becomes frequent and deep, upon reaching a height of 4-5 km, the depth of respiration decreases; B) does not change when rising to a height of 4-5 km, then deepens; C) becomes rare and superficial; D) when climbing to a height of more than 2 km, apnea occurs.
41. When does decompression sickness occur?: A) when submerged under water for more than 1 km; B) when rapidly submerged under water more than 1 m; C) when moving from an area of high to an area of normal atmospheric pressure; D) with a rapid return from the area of high to the area of \u200b\u200bnormal atmospheric pressure.
42. Cause of decompression sickness: A) severe hypoxia; B) accumulation of acidic products in the blood; C) blockage of capillaries with nitrogen bubbles; D) increased levels of carbon dioxide in the blood.
43. How do the lungs participate in blood coagulation?: A) blood that has passed through the lungs coagulates faster; B) heparin is synthesized in the lungs. thromboplastin, VII and VIII coagulation factors; C) lungs - the only organ where plasma coagulation factors are synthesized; D) healthy lungs do not participate in blood coagulation.
44. How much blood is deposited in the lungs?: A) up to 5 l; B) not more than 100 ml; C) up to 1 l; D) up to 80% of circulating blood.
45. What substances are excreted by the lungs from the body?: A) methane, ethane, hydrogen sulfide; B) nitrogen, helium, argon, neon; C) carbon dioxide, water vapor, alcohol vapor, gas drugs; D) ammonia, creatine, creatinine, urea, uric acid.
46. Which of the following substances are destroyed in the lung tissue?: A) acetylcholine, norepinephrine; B) bradycanin, serotonin; C) prostaglandins E and F; D) all of the above.
47. Does lung tissue take part in immune reactions?: A) no; B) yes, lung macrophages destroy bacteria, thromboemboli, fat droplets; C) is only involved in people with exposed bone marrow; D) is only involved in the occurrence of lung cancer.
The Claude Bernard Experience(1851). After transection of the sympathetic nerve on the neck of the rabbit after 1-2 minutes. observed significant expansion vessels auricle, which manifested itself in redness of the skin of the ear and an increase in its temperature. When the peripheral end of this cut nerve was irritated, the skin, reddened after cutting the sympathetic fibers, became pale and cold. This occurs as a result of narrowing of the lumen of the vessels of the ear.
| Rice. 11. Rabbit ear vessels; on the right side, where the vessels are sharply dilated, the sympathetic trunk on the neck is cut | ||||
| Brongest experience. Experience helps to understand the mechanism of muscle tone. The lumbar plexus is found on the spinal frog, by making an incision about 1 cm to the side of the pelvis, a ligature is brought under the plexus. Having fixed the frog by the lower jaw on a tripod, mark a symmetrical half-bent position lower extremities: equality of the angles formed by the thigh and lower leg, lower leg and foot on both limbs and the same horizontal level of the fingers. Then the lumbar plexus is tightly bandaged and after a few minutes the angle and length of both legs are compared. It is noted that the operated paw is slightly elongated as a result of the elimination of muscle tone. | Fig.12. The Brongest Experience | |||
Gaskell's experience. Gaskell used the fact of the influence of temperature on the rate of physiological processes to experimentally prove the leading role of the sinus node in the automatism of the heart. If you heat or cool different parts of the frog's heart, it turns out that the frequency of its contraction changes only when the sinus is heated or cooled, while a change in the temperature of other parts of the heart (atria, ventricle) affects only the strength of muscle contractions. Experience proves that impulses to contract the heart arise in the sinus node.
Levy's experience. There are many examples that the creative work of the human brain occurs during sleep. So, it is known that it was in a dream that D.I. Mendeleev “appeared” the Periodic system chemical elements. A decisive experiment that proved the chemical mechanism of transmission nerve signals, dreamed of the Austrian scientist Otto Levi. He later recalled: “On the night before Easter Sunday, I woke up, turned on the light and jotted down a few words on a tiny piece of paper. Then he fell asleep again. At six o'clock in the morning I remembered that I had written something very important, but I could not make out my careless handwriting. The next night, at three o'clock, sleep visited me again. It was the idea of an experiment that would test whether the chemical transmission hypothesis was correct, which had haunted me for seventeen years. I immediately got up, rushed to the laboratory and performed a simple experiment on the heart of a frog, according to my nightly dream.
Fig.15. O. Levy's experience. A - cardiac arrest with irritation of the vagus nerve; B - stop another heart without irritation of the vagus nerve; 1 - vagus nerve, 2 - irritating electrodes, 3 - cannula
The influence on the myocardium of nerve impulses coming along the autonomic nerves is determined by the nature of the mediator. The parasympathetic nerve mediator is acetylcholine, and the sympathetic nerve mediator is norepinephrine. This was first established by the Austrian pharmacologist O. Levy (1921). He connected two isolated frog hearts to the two ends of the same cannula. Strong irritation of the vagus nerve of one of the hearts caused a stop not only of the heart innervated by this nerve, but also of another, intact, connected with the first only by the general solution of the cannula. Consequently, when the first heart was irritated, a substance was released into the solution that affected the second heart. This substance was called "vagusstoff" and later turned out to be acetylcholine. With a similar stimulation of the sympathetic nerve of the heart, another substance was obtained - "sympathicusstoff", which is adrenalin or but-adrenaline, similar in their chemical structure.
In 1936, O. Levy and G. Dale received the Nobel Prize for the discovery of the chemical nature of the transmission of a nervous reaction.
Mariotte's experiment (detection of the blind spot). The subject holds a drawing of Mariotte with outstretched arms. Closing his left eye, he looks at the cross with his right eye, and slowly brings the drawing closer to the eye. At a distance of approximately 15-25 cm, the image of the white circle disappears. This happens because when the eye fixes the cross, the rays from it fall on yellow spot. The rays from the circle at a certain distance of the pattern from the eye will fall on the blind spot, and the white circle will cease to be visible.
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Fig.16. Mariotte drawing
Matteucci experiment (experiment of secondary contraction). Two neuromuscular preparations are prepared. The nerve of one preparation is left with a piece of the spine, while the other piece of the spine is removed. The nerve of one neuromuscular preparation (with a piece of the spine) is placed with a glass hook on the electrodes that are connected to the stimulator. The nerve of the second neuromuscular preparation is thrown over the muscles of this preparation in the longitudinal direction. The nerve of the first neuromuscular preparation is subjected to rhythmic stimulation, the action potentials arising in the muscle during its contraction cause excitation of the nerve of another neuromuscular preparation superimposed on it and contraction of its muscle.
Rice. 17. The Matteucci Experience
Stannius Experience consists in the successive application of three ligatures (dressings) that separate the sections of the frog's heart from each other. The experiment is carried out to study the ability to automate various parts of the conduction system of the heart.
Fig.18. Scheme of Stannius' experiment: 1 - the first ligature; 2 - the first and second ligatures; 3 - the first, second and third ligatures. dark color the parts of the heart that contract after ligatures are indicated
Sechenov's experiment (Sechenov's inhibition). Braking in the center nervous system was discovered by I.M. Sechenov in 1862. He observed the occurrence of inhibition of spinal reflexes during stimulation of the diencephalon ( thalamus) frog crystal salt. Outwardly, this was expressed in a significant decrease in the reflex reaction (an increase in the time of the reflex) or its termination. The removal of a salt crystal led to the restoration of the initial reflex time.
| B |
Fig.19. Scheme of I.M. Sechenov's experiment with irritation of the visual tubercles of a frog. A - successive stages of exposure of the frog brain (1 - the skin flap cut over the skull is bent; 2 - the roof of the skull is removed and the brain is exposed). B - frog brain with a cut line for Sechenov's experiment (1 - olfactory nerves; 2 - olfactory lobes; 3 - large hemispheres; 4 - cut line passing through the diencephalon; 5 - midbrain; 6 - cerebellum; 7 - medulla oblongata ). B - the place of imposition of salt crystals
Frederick-Heymans experiment (experiment with cross-circulation). In the experiment, some carotid arteries of dogs (I and II) are ligated, while others are connected crosswise with each other using rubber tubes. As a result, the head of dog I is supplied with the blood flowing from dog II, and the head of dog II is supplied with the blood of dog I. If the trachea of dog I is clamped, then the amount of oxygen in the blood flowing through the vessels of its body will gradually decrease in the amount of oxygen and increase in the amount of carbon dioxide. However, the cessation of oxygen supply to the lungs of dog I is not accompanied by an increase in its respiratory movements, on the contrary, they soon weaken, but dog II begins to have very severe shortness of breath.
Since there is no neural connection between the two dogs, it is clear that irritant effect lack of oxygen and excess carbon dioxide is transmitted from the body of dog I to the head of dog II through blood flow, i.e. . humorally. The blood of dog I, overloaded with carbon dioxide and poor in oxygen, entering the head of dog II, causes excitation of its respiratory center. As a result, dog II develops shortness of breath, i.e. increased ventilation of the lungs. At the same time, hyperventilation leads to a decrease (below the norm) in the content of carbon dioxide in the blood of dog II. This carbon-depleted blood enters the head of dog I and causes a weakening of its respiratory center, despite the fact that all the tissues of this dog, with the exception of those of the head, suffer from severe hypercapnia (excess CO 2 ) and hypoxia (lack of O 2 ) due to the cessation of air into her lungs.
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Fig.20. Experience with cross circulation
Bell Magendie's law to the spinal cord afferent nerve fibers enter into the composition of the posterior (dorsal) roots, and the efferent ones come out of spinal cord in the anterior (ventral) roots.
Gaskell's Gradient Law of Automation - the degree of automation is the higher, the closer the area of the conduction system is to the sinoatrial node (sinoatrial node 60-80 imp/min., atrioventricular node - 40-50 imp/min., bundle of His - 30-40 imp/min., Purkinje fibers - 20 imp/min. ).
Rubner's body surface law - The energy costs of a warm-blooded organism are proportional to the surface area of the body.
Frank Starling's Law of the Heart(the law of the dependence of the energy of myocardial contraction on the degree of stretching of its constituent muscle fibers) - the more the heart muscle is stretched during diastole, the more it contracts during systole. Therefore, the strength of heart contractions depends on the initial length of the muscle fibers before the start of their contraction.
Theory of three-component color vision of Lomonosov-Jung-Helmholtz - There are three types of cones in the vertebrate retina, each containing a specific color-reactive substance. Due to the content of various color-reactive substances, some cones have an increased excitability to red, others to green, and still others to blue-violet.
The theory of circular activation currents of Heimans (the theory of the spread of excitation along the nerves) - during the nerve impulse each point of the membrane generates an action potential anew, and thus the wave of excitation "runs" along the entire nerve fiber.
Bainbridge reflex- with an increase in pressure at the mouths of the hollow veins, the frequency and strength of heart contractions increase.
Hering's reflex reflex decrease in heart rate when holding the breath at the height of a deep breath.
Char reflex- decrease in heart rate or even complete cardiac arrest when irritated by mechanoreceptors of organs abdominal cavity or peritoneum.
Danini-Ashner reflex(ocular reflex) – decrease in heart rate with pressure on the eyeballs.
Reflex Parin- with an increase in pressure in the vessels of the pulmonary circulation, cardiac activity is inhibited.
Dale's principle - one neuron synthesizes and uses the same mediator or the same mediators in all branches of its axon (in addition to the main mediator, as it turned out later, other accompanying mediators that play a modulating role - ATP, peptides, etc.).
The principle of M.M. Zavadsky (“plus or minus” of interaction)- an increase in the content of the hormone in the blood leads to inhibition of its secretion by the gland, and a lack of stimulation of the release of the hormone.
Bowditch stairs(1871) - if a muscle is irritated with pulses of increasing frequency, without changing their strength, the magnitude of the contractile response of the myocardium will increase for each subsequent stimulus (but up to a certain limit). Outwardly, it resembles a staircase, so the phenomenon is called the Bowditch stairs. ( with an increase in the frequency of stimulation, the force of heart contractions increases).
Phenomenon of Orbeli-Ginetsinsky. If, by stimulating the motor nerve, the frog muscle is brought to fatigue, and then simultaneously irritated by the sympathetic trunk, then the performance of the tired muscle increases. By itself, stimulation of sympathetic fibers does not cause muscle contraction, but changes the state muscle tissue, increases its susceptibility to impulses transmitted through somatic fibers.
Anrep effect(1972) lies in the fact that with an increase in pressure in the aorta or pulmonary trunk, the force of heart contractions automatically increases, thereby providing the possibility of ejection of the same volume of blood as with the initial value blood pressure in the aorta or pulmonary artery, i.e. the greater the counterload, the greater the force of contraction, and as a result, the constancy of systolic volume is ensured.
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| FOREWORD…………………………………………………... | |
| A BRIEF HISTORY OF THE DEVELOPMENT OF PHYSIOLOGY …………… | |
| THE SIGNIFICANCE OF LABORATORY ANIMALS IN THE DEVELOPMENT OF PHYSIOLOGY ………………………………………. | |
| PERSONALITIES ……………………………………………………. | |
| Avicenna …………………………………………………. | |
| Anokhin P.K. ………………………………………………… | |
| Banting F. ………………………………………………... | |
| Bernard K. …………………………………………………. | |
| Vesalius A. ………………………………………………... | |
| Leonardo da Vinci ………………………………………. | |
| Volta A. …………………………………………………. | |
| Galen K. …………………………………………………... | |
| Galvani L. ……………………………………………….. | |
| Harvey W. …………………………………………………. | |
| Helmholtz G. ……………………………………………. | |
| Hippocrates ………………………………………………… | |
| Descartes R. …………………………………………………. | |
| Dubois-Reymond E. ………………………………………… | |
| Kovalevsky N.O. ………………………………………... | |
| Lomonosov M.V. …………………………………………. | |
| Mislavsky N.A. ………………………………………… | |
| Ovsyannikov F.V. …………………………………………. | |
| Pavlov I.P. ………………………………………………. | |
| Samoilov A.F. …………………………………………… | |
| Selye G. ……………………………………………………… | |
| Sechenov I.M……………………………………………… | |
| Ukhtomsky A.A. …………………………………………. | |
| Sherrington C.S. ………………………………………… | |
| NOBEL LAUREATES IN MEDICINE AND PHYSIOLOGY ………………………………………………………. | |
| AUTHOR'S EXPERIENCES, LAWS, REFLEXES ……………….. | |
| LITERATURE ……………………………………………………... |
Have you heard about such an experiment on wine experts? I once was in France, where we tried 10-15 varieties of cognac costing from 100 to 10,000 dollars per bottle - I could not distinguish anything at all. Firstly, not a specialist at all and there is no rich drinking experience, and secondly, cognac is still a strong thing.
But what they write about experiments with wine seems to me very exaggerated, simplified, or their experts are so useless. See for yourself.
Once in Boston, a wine tasting took place, in which famous connoisseurs of this drink took part. The wine tasting rules were very simple. Twenty-five of the best wines, the price of which should not exceed $12, were bought in a regular store in Boston. Later, a group of experts was formed to evaluate red and white wines, who had to blindly select the best wine from the presented ...
As a result, the winner was the cheapest wine. This once again confirms that tasters and wine critics are a myth. Based on the results of the analysis of the experts' answers, it was revealed that all the tasters chose the wine that they simply liked the most in terms of taste. Here are the "experts" for you.
By the way, in 2001, Frederic Brochet of the University of Bordeaux, conducted two separate and very revealing experiments on tasters. In the first test, Brochet invited 57 experts and asked them to describe their impressions of just two wines.
Before the experts stood two glasses, with white and red wine. The trick was that there was no red wine, in fact it was the same white wine, tinted food coloring. But that hasn't stopped experts from describing "red" wine in the language they usually use to describe red wines.
One of the experts praised its "jamminess" (jam-like), and the other even "felt" "crushed red fruit". No one noticed that it was actually white wine!!!
Brochet's second experiment turned out to be even more devastating for critics. He took a regular Bordeaux and bottled it in two different bottles with different labels. One bottle was "grand cru", the other - the usual table wine.
Even though they actually drank the same wine, the experts judged them differently. The "grand cru" was "pleasant, woody, complex, balanced and enveloping", while the dining room was, according to experts, "weak, bland, unsaturated, simple".
At the same time, most of them did not even recommend "table" wine for drinking.
Experts are indicators of fashion and their taste is no different from the sense of taste ordinary person. It's just that people want to listen to someone else's opinion, that's what an "expert" is for.
The question arises: Are there "experts"? In other words, we are different people, and our tastes vary just like the brands of cheap wine, some people like them, and some don't.
Or still, if not the brand and year of harvest, then white and red wine, then even a weak expert can definitely distinguish? How do you feel about wine experts?
Breathing regulation
- this is a coordinated nervous control of the respiratory muscles, which sequentially carry out respiratory cycles consisting of inhalation and exhalation.
respiratory center - this is a complex multi-level structural and functional formation of the brain, which performs automatic and voluntary regulation of breathing.
Breathing is an automatic process, but it lends itself to arbitrary regulation. Without such regulation speech would be impossible. However, breath control is based on reflex principles: both unconditioned reflex and conditioned reflex.
The regulation of breathing is based on general principles automatic regulation that are used in the body.
Pacemaker neurons (neurons - "rhythm makers") provide automatic the occurrence of excitation in the respiratory center even if the respiratory receptors are not irritated.
inhibitory neurons provide automatic suppression of this excitation after a certain time.
The respiratory center uses the principle reciprocal (i.e. mutually exclusive) interaction of two centers: inhalation and exhalation . Their excitation is inversely proportional. This means that the excitation of one center (for example, the center of inhalation) inhibits the second center associated with it (the center of exhalation).
Functions of the respiratory center
- Ensuring inspiration.
- Ensuring exhalation.
- Ensuring automatic breathing.
- Ensuring adaptation of breathing parameters to conditions external environment and activities of the body.
For example, when the temperature rises (as in environment, and in the body) breathing quickens.
Respiratory center levels
1. Spinal (in the spinal cord). In the spinal cord there are centers that coordinate the activity of the diaphragm and respiratory muscles - L-motoneurons in the anterior horns of the spinal cord. Diaphragmatic neurons - in the cervical segments, intercostal - in the chest. When the pathways between the spinal cord and the brain are cut, breathing is disturbed, because. spinal centers do not have autonomy (i.e. independence) and do not support automation breathing.
2. bulbar (in the medulla oblongata) - main department respiratory center. In the medulla oblongata and the pons, there are 2 main types of neurons of the respiratory center - inspiratory(inhalation) and expiratory(expiratory).
Inspiratory (inhalation) - are excited 0.01-0.02 s before the start of active inspiration. During inspiration, they increase the frequency of impulses, and then instantly stops. They are divided into several types.
Types of inspiratory neurons
By influence on other neurons:
- inhibitory (stop breathing)
- facilitating (stimulate breathing).
By excitation time:
- early (a few hundredths of a second before inspiration)
- late (active during the entire inhalation).
By connections with expiratory neurons:
- in the bulbar respiratory center
- in the reticular formation of the medulla oblongata.
In the dorsal nucleus, 95% are inspiratory neurons; in the ventral nucleus, 50%. The neurons of the dorsal nucleus are associated with the diaphragm, and the ventral - with the intercostal muscles.
Expiratory (expiratory) - excitation occurs a few hundredths of a second before the start of exhalation.
Distinguish:
- early,
- late
- expiratory-inspiratory.
In the dorsal nucleus, 5% of neurons are expiratory, and in the ventral nucleus, 50%. In general, there are significantly fewer expiratory neurons than inspiratory neurons. It turns out that inhalation is more important than exhalation.
Automatic breathing is provided by complexes of 4 neurons with the obligatory presence of inhibitory ones.
Interaction with other centers of the brain
Respiratory inspiratory and expiratory neurons have access not only to the respiratory muscles, but also to other nuclei of the medulla oblongata. For example, when the respiratory center is excited, the swallowing center is reciprocally inhibited and at the same time, on the contrary, the vasomotor center for regulating cardiac activity is excited.
At the bulbar level (i.e. in the medulla oblongata), one can distinguish pneumotaxic center , located at the level of the pons, above the inspiratory and expiratory neurons. This center regulates their activity and provides a change in inhalation and exhalation. Inspiratory neurons provide inspiration and at the same time excitation from them enters the pneumotaxic center. From there, the excitation runs to the expiratory neurons, which fire and provide exhalation. If the pathways between the medulla oblongata and the pons are cut, then the frequency of respiratory movements will decrease, due to the fact that the activating effect of PTDC (pneumotactic respiratory center) on inspiratory and expiratory neurons decreases. This also leads to a lengthening of inhalation due to the long-term preservation of the inhibitory effect of expiratory neurons on inspiratory neurons.
3. Suprapontal (i.e. "suprapontial")
- includes several areas of the diencephalon:
The hypothalamic region - when irritated, causes hyperpnea - an increase in the frequency of respiratory movements and the depth of breathing. The posterior group of nuclei of the hypothalamus causes hyperpnea, the anterior group acts in the opposite way. It is due to the respiratory center of the hypothalamus that breathing reacts to the ambient temperature.
The hypothalamus, together with the thalamus, provides a change in breathing during emotional reactions.
Thalamus - provides a change in breathing during painful sensations.
Cerebellum - adjusts breathing to muscle activity.
4. Motor and premotor cortex
large hemispheres of the brain. Provides conditioned reflex regulation of breathing. In just 10-15 combinations, you can develop a respiratory conditioned reflex. Due to this mechanism, for example, athletes develop hyperpnea before the start.
Asratyan E.A. in his experiments, he removed these areas of the cortex from animals. During physical exertion, they quickly developed shortness of breath - dyspnea, because. they lacked this level of breath regulation.
The respiratory centers of the cortex enable voluntary changes in breathing.
Regulation of the respiratory center
The bulbar department of the respiratory center is the main one, it provides automatic breathing, but its activity can change under the influence of humoral
and reflex
influences.
Humoral influences on the respiratory center
Frederick's Experience (1890). He did cross circulation in two dogs, the head of each dog received blood from the torso of the other dog. In one dog, the trachea was clamped, consequently, the level of carbon dioxide increased and the level of oxygen in the blood decreased. After that, the other dog began to breathe rapidly. There was hyperpnea. As a result, the level of CO2 in the blood decreased and the level of O2 increased. This blood flowed to the head of the first dog and inhibited its respiratory center. Humoral inhibition of the respiratory center could bring this first dog to apnea, i.e. stop breathing.
Factors that have a humoral effect on the respiratory center:
Excess CO2 - hypercarbia, causes activation of the respiratory center.
Lack of O2 - hypoxia, causes activation of the respiratory center.
Acidosis - accumulation of hydrogen ions (acidification), activates the respiratory center.
Lack of CO2 - inhibition of the respiratory center.
Excess O2 - inhibition of the respiratory center.
Alcolosis - +++ inhibition of the respiratory center
The neurons of the medulla oblongata themselves high activity produce a lot of CO2 and locally affect themselves. Positive feedback (self-reinforcing).
In addition to the direct action of CO2 on the neurons of the medulla oblongata, there is a reflex action through reflex zones of cardio-vascular system(Reimans reflexes). With hypercarbia, chemoreceptors are excited and from them excitation goes to chemosensitive neurons of the reticular formation and to chemosensitive neurons of the cerebral cortex.
Reflex effect on the respiratory center.
1. Permanent influence.
Geling-Breuer reflex. Mechanoreceptors in the tissues of the lungs and airways are excited by stretching and collapse of the lungs. They are stretch sensitive. From them, impulses along the vacus (vagus nerve) goes to the medulla oblongata to the inspiratory L-motoneurons. Inhalation stops and passive exhalation begins. This reflex provides a change in inhalation and exhalation and maintains the activity of the neurons of the respiratory center.
When the vacus is overloaded and transected, the reflex is canceled: the frequency of respiratory movements decreases, the change of inhalation and exhalation is carried out abruptly.
Other reflexes:
stretching of the lung tissue inhibits the subsequent breath (expiratory-facilitating reflex).
Stretching of the lung tissue during inhalation normal level causes an extra breath (Head's paradoxical reflex).
Heimans reflex - arises from the chemoreceptors of the cardiovascular system to the concentration of CO2 and O2.
Reflex influence from the propreoreceptors of the respiratory muscles - when the respiratory muscles contract, a flow of impulses from the propreoreceptors to the central nervous system occurs. According to the feedback principle, the activity of inspiratory and expiratory neurons changes. With insufficient contraction of the inspiratory muscles, a respiratory-facilitating effect occurs and inspiration increases.
2. Fickle
Irritant - located in the airways under the epithelium. They are both mechano- and chemoreceptors. They have a very high irritation threshold, so they work in extraordinary cases. For example, with a decrease in pulmonary ventilation, the volume of the lungs decreases, irritant receptors are excited and cause a forced inspiration reflex. As chemoreceptors, these same receptors are excited by biologically active substances - nicotine, histamine, prostaglandin. There is a burning sensation, perspiration and in response - a protective cough reflex. In the case of pathology, irritant receptors can cause spasm of the airways.
in the alveoli, juxta-alveolar and juxta-capillary receptors respond to lung volume and biologically active substances in capillaries. Increase the respiratory rate and contract the bronchi.
On the mucous membranes of the respiratory tract - exteroreceptors. Coughing, sneezing, holding your breath.
The skin has heat and cold receptors. Breath holding and breath activation.
Pain receptors - short-term breath holding, then strengthening.
Enteroreceptors - from the stomach.
Propreoreceptors - skeletal muscle.
Mechanoreceptors - from the cardiovascular system.
It so happened that people don't like to read. There is more if it is difficult to read, for example on foreign language, which every second did not know from school, and then also thoroughly forgot. This fact is used with might and main by modern businessmen who put on the market wonderful brochures like "Anna Karenina on 5 pages".
There are many very interesting and really rich topics for reflection in winemaking and wine consumption, for example, about how objective the perception of wine by one or another person can be. About how much in reality a person feels and experiences some emotions when tasting wine, and to what extent he thinks them up for himself. These are excellent questions that deserve serious thought and discussion. But here's the problem - for a serious level of discussion of any issue, including this one, you must first spend a significant number of hours on its comprehension in various aspects and studying all the existing works done earlier on this topic.
And this is a lot of work, which requires, first of all, the skill of serious analytical reading. To which, as I mentioned above, people in the mass are not capable. Therefore, I will have to practice today in arranging the "theory differential equations in partial derivatives for preschool reading".
We will talk about the experiment (more precisely, about the first part of the experiment) Frederic Brochet, which, with the filing of tabloid journalists eager for "yellow" and "fried", has gained wide notoriety as "deception of tasters". The essence of the experiment was that the author took white wine, poured it into two containers and tinted one of the containers with tasteless food red dye. Then he asked his subjects, whom he recruited "through an ad" on the university campus, to describe the taste and aroma of each wine.
As a result, those students who tried "white" wine talked about its aroma using associations with white fruits and flowers, mentioning lilies of the valley, peaches, melon, etc., and those subjects who tried "red" wine talked about roses, strawberries and apples. Nothing in common! Hooray! The tasters all lie and don't really understand anything, we brought them to clean water! General celebration and rejoicing!
Seemingly. In fact, the situation is simple and banal: none of us have ever been taught to describe the taste and aroma in words. No one and no country in the world. As well as color. Or sound. Try to tell what does it look like blue color and you will run into a big problem, which is that the phrase "radiation with a wavelength of about 440-485 nm" does not say anything at all to anyone. This is actually a simple experiment available to everyone. Get up from your chair and approach 10-20 people with the question "what does the color blue look like?". And a man who has recently been to the sea will say first of all " on the sea", aviation lover - " On sky", nerd - " on cornflowers"geologist -" for lapis lazuli and sapphire"and so on. Nothing in common! Does this mean that do people really not see colors?
Trying to tell another person about those sensations (in the case of colors - visual), for which there are no established common standards, we call for help associations, trying to pick up something that is closest, most similar and most familiar to everyone. Associations, mental images, ideas. No more.
Does the color of an object matter? what associations do we come up with? Undoubtedly! In the illustration to this text there is a picture with two images of speed, which the artists embodied in the coloring of cars. What do a snowstorm and a fast-moving forest fire have in common? One is white, cold, prickly, piercing, freezing. The other is ruthlessly scorching, assertive, leaving behind fumes, smoke and ashes. But does this mean that in fact "there is no speed!"? Of course not! She eats great. Did the original color of the car influence the choice of metaphor, association, idea for the picture? Undoubtedly! Is there any sensation in this? Not for a penny.
But who cares?