Mistchenko V.P., Tkachenko E.V.

Mistchenko V.P., Tkachenko E.V.

NORMAL PHYSIOLOGY

(SHORT LECTION COURSE FOR THE STUDENTS OF DENTAL DEPARTMENT)

 

 

POLTAVA- 2005

 

 

Dear students!

In a brief course of our lectures on normal physiology for the students of dental faculty, offered to you, the basic concepts about all human organism systems functioning are stated. It is natural, that because of material statement brevity due to very much lectures amount, they can not give the complete answer to numerous questions, which can appear at their reading, all the more so there is no illustrative material in them. However, from our point of view, these lectures can be good addition to the existing textbooks and manuals. All the more so we read lectures from a position of clinical physiology, and not just from those classical performances about physiology, which are stated in the bulk of educational literature. It all does not mean, that in our lectures the knowledge of classical physiology is not used. The thing is that the knowledge is so quickly replenishes with the new items of information, that the known textbooks and manuals at any stage and in any sections obviously lag behind modernity. Besides you have paid, obviously, attention, that in each lecture devoted to this or that physiology section there is a material, in which the data on its value for the doctor – dentist are submitted. In any measure our lectures supplement the elements of dental disciplines propedeutics. Moreover, they contain as well the data, which undoubtedly can be very useful to you at a study of internal diseases, surgery and other clinical disciplines. Especially it concerns dental specialities (sections of therapy, surgery, orthopedics). Whether it is possible to do without our lectures? It is naturally possible. But we consider, that the alive dialogue with the lecturer cannot be replaced by any manuals. Believe our experience, you, being trained on the senior courses, will open these lectures time and again! We wish a success to you!

Yours faithfully, professor V.P.Mishenko and assistant E.V.Tkachenko.

 

 

Lection 1.

Segment ST - is a right line section on isoelectric axis from dens S end till dens T beginning and describes the moment when both ventricles are simultaneousely excited. Its duration is from 0,1 till 0,15 sec.

Dens T – describes myocardium repolarization process, it altitude is 0,4-0,8 mV, duration – 0,1-0,25 sec. In I it is always positive, in II - often positive and in III – may be positive, two-phased and negative. In V₁-V₂ it is negative sometimes, in aVF – usually negative.

Interval TP – characterizes common heart pause, its duration is 0,4 sec.

Interval R-R – characterizes complete cardiac cycle, its duration is 0,8 sec.

Complex P – atrial.

Complex QRST – ventricular.

As heart excitation begins from its base, than this region is a negative pole, apex region – positive one. Heart electromoving force (EMF) has its size and direction. EMF direction is considered to call heart electrical axis. In the most common cases it is located in parallel to heart anatomical axis (normogram). Direction of one or another dens on ECG reflects an integral vector direction. When vector is directed to heart apex, one can registrate positive (as for electrical axis) denses, if to the heart base - negative. Due to definite heart location in thorax and human body shape, electrical force lines occuring between excited and unexcited heart locus, are distributed unequally on body surface. If heart axis becomes horizontal (lying heart) than such situation is called left-gram, in a case of its vertical localization (hanging heart) – right-gram.

Humoral-chemical regulation

of heart and vessels activity is determined by hormones, mediators and different chemical substances (metabolites) action.

Substances increasing heart and vessels activity:

Hormones:

· adrenaline;

· noradrenaline;

· vasopressine;

· thyroxine;

· insuline;

· renine et al.

Mediators:

· noradrenaline;

· serotonine and others.

Metabolites:

· calcium excess;

· oxygen excess.

Substances decreasing heart and vessels activity:

· acethylcholine;

· hystamine;

· many prostaglandines (f.ex. prostacycline);

· acids (lactic et al.);

· CO₂ surplus (excess).

Acid products (lactic acid, CO₂) accumulating in course of physical activity decrease tone of working muscles blood vessels increasing blood supply to them. At this time magistral vessels are in increased tone due to adrenaline and noradrenaline concentration increasing in answer to load. Such tone redistribution in different vessels of blood circulation system provides high reliability of a given system functionning.

Thus, we see that heart-vascular activity regulation is a complicated process in what both reflectory (conditioned and unconditioned) and humoral-chemical mechanisms take part.

How and in what sequence these mechanisms are switched on under physiological conditions for instance in course of physical work? At this activity type increased oxygen consumption and enforced carbon dioxide releasing occurs. It may be achieved due to increased activity not only of respiration system but also blood circulation apparatus. Describe the consequence of switching of all these regulatory mechanisms on. At the early beginning, in the period of preparation to work the blood circulation system activity is increased by means of 2 mechanisms: conditioned-reflectory and humoral. Conditioned-reflectory – the situation itself before physical activity (sportsmen before running) is conditioned stimuli complex (in example with sportsman these are running way, stadium, spectators, referees and so on) which will cause the changes from the side of heart and vessels. Emotional load at this is a reason of enforced adrenaline releasing from suprarenal glands. The result of this is more expressed increasing of heart and vessels activity. Organism prepares given (cardiac-vascular) system to future wok in such a way.

In course of performing of physical activity itself conjugated reflexes from proprioreceptors, proper reflexes from chemoreceptors (metabolism products accumulation and first of all CO₂) are involved into regulation and hormones (adrenaline, vasopressine et al.) continue to be released. All these factors encourage further heart and vessels activity increasing. At the same time in working organs (muscles) acid products are accumulated, decreasing vessels tone in these organs and blood fills them in more extent providing feeding and removal of metabolism exchange.

After physical activity performing everything came ito its initial level due to involvement ito the work proper receptors from pressoreceptors directed to heart and vessels activity restriction (restoration).

Oxygen transport.

Oxygen partial pressure:

· in atmosphere is equal to 159 mm merc col.;

· in alveoles – 102-105 mm merc col;

· in venous blood reaching alveoles – 40 mm merc col;

· pressure gradient for oxygen between alveoles and blood is about 60 mm merc col.

Thus, oxygen due to this difference of partial pressure and its tension in different environments passes from atmosphere into alveoles and then in blood and tissues. How oxygen is transmitted?

Oxygen transfer conditions

It is known that blood tranfers 300-350 ml of oxygen for 1 minute under relative rest state (this ziphra significantly increases at physical work). One can differentiate 2 factors of oxygen transfer:

· large alveolar surface (60-100 square meters);

· oxygen fast diffusion ability – at this difference between alveoles and blood in 1 mm merc col 200 ml of oxygen will diffund; at a real difference that is 60 mm merc col – 12000 ml of oxygen (!even in course of intensive physical loading this ziphra is not more than 4000-5000 ml!). You see data about oxygen diffuse ability: it predominates the level necessary for intensive physical trainings in 2,5-3,0 times.

Oxygen transport forms

Particularly oxygen can be dissolved (in 100 ml of blood – up to 0,3 ml of oxygen, thus, in all blood – about 15 ml). Of course, it can’t solve the problem of oxygen transport. Main chemical substance necessary for oxygen transport is oxyhaemoglobine. It was estimated that 1 g of haemoglobine can transmits approximately 1,31 ml of oxygen. 100 ml of blood contains about 14-16 g of haemoglobine, so, they can carry 18-21 ml of oxygen. This index is known as oxygen blood capacity – is is defined as oxygen amount transporting with 100 ml of blood till its full saturation. This index can be changed. It is rised up in course of physical training, at polycitaemia; reduced – at blood diseases for instance at anaemias.

Formed oxyhaemoglobine amount depends on oxygen partial pressure in blood. This dependence is linear that is proved by following data. At oxygen partial pressure equal to 0, oxyhaemoglobine isnt’t formed; 10 mm merc col. – 10% oxyhaemoglobine; 20 mm.- 30%; 40 mm. – 70%; 70 mm.- 90%; 100 mm. – 96%. If we connect all this points we shall receive curve describing dependence between oxygen tension in blood and amount of forming oxyhaemoglobine. This curve name is oxyhaemoglobine dissociation curve. One can make some important conclusions from this curve:

1) At oxygen partial tension decreasing in blood up to 80-70 mm merc col (it corresponds to such partial pressure in mountains at a high 2500-3000 meters above sea level) amount of formed oxyhaemoglobine decreases insignificantly, i.e. its amount is less only on several per cents than on plain. It gives the possibilities to successful work of mountaineers, highland workers and also to life in highlands without any additional devices and forces. At a high level above 4000 metres we’ll not be able to breath without additional oxygen coming from gas cylinder.

2) Venous blood is rich in oxyhaemoglobine, i.e. it is saturated by oxygen. At partial tension in venous blood equal to 40 mm merc col, up to 70% of oxyhaemoglobine is formed in blood.

3) Difference between oxyhaemoglobine content in arterial and venous blood is 25-26%. Oxyhaemoglobine content in arterial blood is 95-96%, in venous – 70%. This index is named arterio-venous difference. It is rised up in course of physical training, at polycitaemia; reduced – at blood (at anaemias) and heart disorders.

Oxyhaemoglobine dissociation curve moving:

1) to the left (up) – is observed:

· at temperature decreasing;

· pH increasing (alkalosis);

· hypocapnia;

· in blood reaching lungs;

· in new-borns;

· in mountaineers;

· in fliers;

· in cosmonauts.

Essence: at less oxygen partial pressure in atmosphere to form more oxyhaemoglobine in blood.

2) To the right (down) – is observed:

· at hyperthermia;

· at fever;

· pH decreasing (acidosis);

· carbonic acid content increasing;

· in blood reaching tissues (for example, working muscles).

Essence: at the same oxygen partial tension oxygen forming is less and free oxygen comes to the tissue where it’s necessary for redox reactions performing in them.

Carbon dioxide transport

Carbon dioxide transmission and transfer is realized by same machanisms. Carbon dioxide tension:

· in tissues – maximal – 60 mm merc col.;

· in venous blood outflowing from tissues – 46 mm;

· in alveoles where venous blood inflows – 38 mm merc col;

· in atmosphere – 0,2 mm merc col.

It’s quite naturally that pressure and tension gradient in different organism environments and compartments provides carbonic dioxide transition from tissues to blood, from blood into alveoles and from alveoles into surrounding space.

Carbon dioxide forms

Particularly, like oxygen, in little amounts it can dissolve (3-6%). Rest part comes into chemical connections both in plasma and in erythrocytes. Chemical substance of carbonic dioxide with water – carbonic acid (H₂CO₃) – appears in plasma. It takes place because partial tension of this gas is more than in blood, that’s why it transfers into blood plasma where is connected to water. Carbonic acid part in plasma is connected to sodium chloride as the result of which soda is formed (NaHCO₃). Plasma transports carbonic dioxide in composition of theses compounds. Its rest part reaches erythrocytes where under influence of special erythrocytic enzyme carboanhydrase the possibility of its connection with water is significantly increased with carbonic acid forming. Little amount of this acid is binded with potassium chloride with potassium bicarbonic (KHCO₃) formation. Finally, carbon dioxide part is binded to amine group of haemoglobine with the carbohaemoglobine (KHCO₂)forming. Thus, in erythrocytes carbonic dioxide is transported in a structure of H₂CO₃, KHCO₃ and HbCO₂.

When blood reaches alveoles, same enzyme carboanhydrase acts on the contrary: it helps H₂CO₃ dissociation and CO₂ comes into alveoles as the result of these processes. As oxygen partial pressure in alveoles is higher than in blood the gas passes in blood, in red blood cells with oxyhaemoglobine forming in them. Being more powerful acid than carbonic, oxyhaemoglobine takes the bases from bicarbonates and thus provides carbonic dioxide releasing. The result: CO₂ passes into alveoles. In tissues oxyhaemoglobine transformes into haemoglobine giving bases connected with it, increasing blood saturation with CO₂. These examples testify to the fact that oxygen plays essential role in CO₂ forming and releasing.

But at all these reactions CO₂ tension in venous blood remains big (46 mm merc col) and it doesn’t differ significantly from its tension in arterial blood. Thus, there exists carbonic dioxide arterio-venous difference equal to 6 mm merc col.

There is quite natural question: why organism has big amount of CO₂? The answer is the following: it is essential respiration regulator.

Respiration regulation is performed by means of reflectory reactions occuring as a result of excitement of specific receptors located in lung tissue, vascular reflexogenic zones and other regions. Respiration regulation central apparatus are the structures of:

· spine;

· medulla oblongata;

· hypothalamus;

· brain hemispheres.

Main function of respiration management is performed by stem repiratory neurons which transmit rhythmic sygnals into spine to respiratory muscles motoneurons.

Respiratory nervous center – is central nervous system neurons integrity providing respiratory muscles co-ordinated rhythmical activity and external respiration constant adaptation to changing conditions inside organism and in environment. Main (working) part of respiratory nervous center is located in medulla oblongata. One can differentiate 2 parts in it: inspiratory (inspiration center) and expiratory (expiration center). Medulla oblongata respiratory neurons dorsal group primarily consists of inspiratory neurons. They give particularly the stream of descendant ways getting the contact with diaphragmal nerve motoneurons. Respiratory neurons ventral group sends primarily descendant fibres to intercostal muscles motoneurons. One can see region in pons anterior part called as pneumotaxic center. This center deals with activity both of inspiratory and expiratory center parts providing the change of inspiration and expiration. Respiratory center important part is neurons group of spine cervical part (III-IV cervical segments), where diaphragmal nerves nuclei are situated.

Respiratory center excitement mechanisms are the following.

· One of the most important ways of its excitement is automatism. There is not one point of view to automatism nature but there exist data about secondary depolarization occurence in respiratory neurons (like diastolic depolarization in myocardium) which reaching its critical level gives new impuls.

· But one of main ways of respiratory center excitement is its irritation by carbonic acid. As it was mentioned above, there remains much carbonic acid in blood leaving lungs. It performs the function of medulla oblongata neurons main irritator. It is mediated through special structures – chemoreceptors, located directly in medulla oblongata structures (“ central chemoreceptors ”). Thus, the second way – through blood.

· They are very sensitive to carbonic dioxide tension and acid-alkaline state of intercellular liquor washing them.

· Carbonic acid can easily diffund from brain vessels in liquor and stimulates medulla oblongata chemoreceptors.

· Reflectory way - there are 2 reflexes groups (like for cardio-vascular system): proper and conjugated.

I. Proper reflexes – the reflexes originated from respiratory system organs and finished in it.

1) Reflex from lung mechanoreceptors. According to localization and type of percepted irritations, reflectory answer to irritation one can differentiate 3 types of such receptors: receptors of stretching, irritant receptors and lung juxtacapillar receptors.

· Lung stretching receptors – are primarily located in air ways (trachea, bronchi) smooth muscles. There are approximately 1000 receptors in every lung and they are connected with respiratory center by large myelinized afferent fibres of vagus with very high conductance velocity. Direct irritator – internal tension in air ways walls tissues. Such impulses freaquency is increased at lung stretching in course of inspiration. Lung swelling causes inspiration reflectory inhibition and transition to expiration. These reactions are stopped at vagus cutting and respiration becomes retarded and deep. Mentioned reactions are called Gering-Breyer’s reflex. This reflex is reproduced in adult person when his respiratory volume is more than 1 l (at physical training for instance). It is of essential importance in new-borns. Their adaptation is slow.

· Irritant receptors or slowly adaptating air ways mechanoreceptors, trachea and bronchi mucosa receptors. They answer to lung volume significant changes, chemical or mechanical irritators (mucus, tobacco, dust particles and so on) action to mucosa. Their adaptation is fast. At side bodies coming into respiratory ways there occurs cough reflex after irritant receptors activation. Reflectory arch of cough reflex – receptors – superior-laryngeal, glosso-pharyngeal, trygeminal nerves – expiratory part of respiratory center. Result - strong expiration – cough. At isolated irritation of nasal respiratory ways receptors second immediate expiration occurs – sneezing.

· Juxtacapillary receptors are located near alveolar and respiratory bronchi capillaries. Irritators: pressure increasing in circulation small circle and intersticial liquid volume increasing in lungs. Such situation is observed at blood stagnation in small circulation circle, lung oedema, lung tissue injury (at pneumonia et al.). Impulses from these receptors are directed to respiratory center through vagus causing freaquent surface breathing occurence. There may be not only freaquent breathing (tachypnoe) but also reflectory bronchoconstriction.

2) Reflexes from respiratory musculature proprioreceptors:

· Reflex from intercostal muscles proprioreceptors is realized in course of inspiration when these muscles while their contraction send information through intercostal nerves to respiratory center expiratory part and as a result expiration occurs.

· Reflex from diaphragm proprioreceptors – is performed as an answer to its contraction in course of inspiration. Result: information comes through diaphragmal nerves first in spine, than in medulla oblongata in its expiratory part and expiration occurs.

Thus, all respiratory system proper (own) reflexes are realized in course of inspiration and are resulted in expiration.

II. Conjugated reflexes – reflexes originated out of respiratory system.

1) Reflex onto conjugation of blood circulation and respiration systems – is originated from perypheral chemoreceptors of vascular reflexogenic zones. The most sensitive of them are located in sino-carotid zone region.

· Sino-carotid chemoreceptive conjugated reflex – is performed at carbonic dioxide accumulation in blood. If its tension increases than the irritation of the most sensitive chemoreceptors (they are in this zone in sino-carotid body) occurs, excitement wave comes from them through IX pair of cranio-cerebral nerves and reaches respiratory center expiratory part. Expiration occurs which enforces releasing of excessive carbonic acid in surrounding space. Thus, blood circulation system (while this reflectory act performance it works more intensively: heart contractioin freaquency and blood stream velocity increase) influences on respiration system.

2) Exteroceptive reflexes are originated from tactile (remember your breathing reaction on touching of lovely person), temperature (warmth – increases, coldness – decreases respiratory function), noceoceptive (weak stimuli and of a middle force - increase, strong – suppress breathing) receptors.

2) Proprioreceptive reflexes – are performed due to irritation of receptors of sceletal muscles, joints, ligaments. It is observed in course of physical training doing. Why? If under rest state it’s necessary 200-300 ml oxygen per minute for human than at physical loading given volume must be significantly increased. Under these conditions both minute volume and arterio-venous difference on oxygen are increased. This indexes increasing is accompanied by oxygen consumption rising up. At work duration of only 2-3 minutes and its significant power oxygen consumption grows uninterruptedly from the very beginning of work and is decreased only after its stoppage. At work duration more, oxygen consumption, while increasing in course of first minutes, is supported all the time on its constant level. Oxygen consumption increases the more the harder physical work it is. Maximal oxygen amount that organism can use per 1 minute at the hardest work for it is called oxygen maximal consumption (OMC). Work at which person reaches his OMC level must have duration not less then 3 minutes. There exist many ways of OMC determining. It doesn’t predominate 2,0-2,5 l/min in untrained people. It can be twice large in sportsmen and even more. OMC is an index of organism aerobic productivity. This human ability to perform very hard physical work, providing his energetic consumption due to oxygen used directly in course of work. It is known that even well-trained person can work at oxygen consumption 90-95% from his OMC level not more than 10-15 min. One having more aerobic productivity reaches better results in work (sport) at practically equal technic adn tactic preparation. Why oxygen consumption is increased in course of physical activity? One can differentiate several reasons:

· additional capillaries opening and blood increasing in them;

· oxyhaemoglobine dissociation curve movement to the right and below;

· temperature increasing in muscles.

For performing their work, muscles need in energy, the accumulations of which are restored while oxygen transport. Thus, there exists definite dependence between work power and oxygen amount necessary for work. That blood amount necessary for work is called oxygen asking. Oxygen asking can reach up to 15-20 liters per minute and even more in course of hard work. But maximum of oxygen consumption is less in 2-3 times. Does it possible to perform the work if minute oxygen accumulation predominates OMC? For correct answer this question one should remember for what oxygen is used in course of muscular activity. It is essential for macroergic substances restoration providing muscular contraction. Usually oxygen interacts with glucose and it releases the energy while its oxidation. But also glucose can be destructed without oxygen, i.e. by abaerobic way as a result of which energy releases too. These are also other substances possessing the ability to be destructed without oxygen. Thus, muscular activity can be provided at insufficient oxygen coming into organism too. But in this case many acid products are formed and it’s necessary oxygen for their destruction because they are destructed by oxidation. Oxygen amount necessary for metabolism products oxidation that were formed in course of physical activity is called oxygen debt. It appearsin course of work and is liquidated in restoration period after work end. Usually this disappearing takes from several minutes to 1 hour and a half. Everything depends on work duration and intensivity. Lactic acid plays the most important role in oxygen debt forming. To continue his work at lactate presence in blood in great amounts organism must have powerful buffer systems and his tissues are to be adapted to work under hypoxy conditions. Such organism adaptation serves as one of factors providing high aerobic productivity. All the mentioned above complicate respiration regulation at physical activity because oxygen taking in organism is increased and its blood hypoxy leads to chemoreceptors irritation. Sygnals from them come in respiratory center as the result of which respiration becomes more freaquent. A great number of carbonic acid is formed in course of muscular activity that comes into blood and it can acts to respiratory center directly through central chemoreceptors. If blood hypoxy leads primarily to breathing quickening than carbonic acid surplus causes its deepening. Both theses factors act simultaneousely in course of physical activity and that’s why respiration quickening and deepening takes place. Finally, impulses coming from working muscles, reach respiratory center and enforces its activity. At respiratory center functionning all its parts are functionally interconnected by means of following mechanism: at carbonic acid accumulation respiratory center inspiratory part is excited from information comes in pneumotaxic part, then to its expiratory part. The latest, besides, is excited by means of a whole group of reflectory acts – from receptors of lungs, diaphragm, intercostal muscles, respiratory ways, vessels chemoreceptors. Inspiration center activity is inhibited due to its excitement through special inhibitory reticular neuron and inspiration is changed by expiration. As expiration center is inhibited it doesn’t send impulses far into pneumotaxic center and information flow is stopped from it to expiration center. Carbonic acid is accumulated in blood by this time and inhibitory influencings on expiratory part are inhibited. Inspiration center is excited due to such information flow redisposition and expiration is changed by inspiration. And everything is repeated again.

Vagus is an essential link in respiration regulation. Main influencings to expiration center come through it. That’s why at its injury (like at pneumotaxic center injury) respiration is changed so that inspiration remains normal and expiration is sharply prolonged – vagus-dyspnoe.

As it was mentioned above in course of coming to the highlands lung ventillation increasing occurs based on vascular zones chemoreceptors stimulation.

Heart contraction freaquency and minute volume are increased simultaneously with this. These reactions improve oxygen transport in organism a little but not for long. That’s why at durable staying into mountains with adaptation to chronic hypoxy initial (urgent) respiration reactions gradually leave their place to more economic adaptation of gas-transport organism system. In constant residents of highlands respiration reaction to hypoxy is too weak (hypoxic deafness) and lung ventillation is supported practically on the same level like in plane residents. At the same time at durable staying under conditions of highlands vital lung capacity, caloric oxygen equivalent, myoglobine content in muscles, mitochondrial enzymes activity (providing biological oxidation and glycolysis) are increased; organism tissues (particularly central nervous system) sensitivity to insufficient oxygen supply is decreased. At high more than 12000 m air pressure is very small and under these conditions even breathing by pure oxygen doesn’t solve the problem. That’s why at flyings at this high one need hermetic cockpits (planes, cosmic ship).

Sometimes human being has to work under increasing pressure conditions (divering). In the depth nitrogen becomes its dissolving in blood and in course of fast rising out off the depth it doesn’t manage to release from blood, gas vesicles cause vessel emboly. Occuring condition is called kessonic disease. It is accompanied by pain in joints, giddiness, dyspnoe, unconsciousness. That’s why nitrogen in air mixtures is changed on insoluble gases (for instance, helium).

Human being can delay free his breath not more than on 1-2 minutes. After preliminary lung hyperventillation this respiration delay is rised up to 3-4 minutes. But durable, for example, diving after hyperventillation is very dangerous. Blood oxygenation sharp decreasing can cause sudden unconsciousness. Under this state swimmer (even experienced one) under stimulus action caused by carbonic acid partial tension increasing in blood can inspirate water and choke (drown).

Lecture 7

Lecture 8

Lecture 9

Mistchenko V.P., Tkachenko E.V.

NORMAL PHYSIOLOGY

(SHORT LECTION COURSE FOR THE STUDENTS OF DENTAL DEPARTMENT)

 

 

POLTAVA- 2005

 

 

Dear students!

In a brief course of our lectures on normal physiology for the students of dental faculty, offered to you, the basic concepts about all human organism systems functioning are stated. It is natural, that because of material statement brevity due to very much lectures amount, they can not give the complete answer to numerous questions, which can appear at their reading, all the more so there is no illustrative material in them. However, from our point of view, these lectures can be good addition to the existing textbooks and manuals. All the more so we read lectures from a position of clinical physiology, and not just from those classical performances about physiology, which are stated in the bulk of educational literature. It all does not mean, that in our lectures the knowledge of classical physiology is not used. The thing is that the knowledge is so quickly replenishes with the new items of information, that the known textbooks and manuals at any stage and in any sections obviously lag behind modernity. Besides you have paid, obviously, attention, that in each lecture devoted to this or that physiology section there is a material, in which the data on its value for the doctor – dentist are submitted. In any measure our lectures supplement the elements of dental disciplines propedeutics. Moreover, they contain as well the data, which undoubtedly can be very useful to you at a study of internal diseases, surgery and other clinical disciplines. Especially it concerns dental specialities (sections of therapy, surgery, orthopedics). Whether it is possible to do without our lectures? It is naturally possible. But we consider, that the alive dialogue with the lecturer cannot be replaced by any manuals. Believe our experience, you, being trained on the senior courses, will open these lectures time and again! We wish a success to you!

Yours faithfully, professor V.P.Mishenko and assistant E.V.Tkachenko.

 

 

Lection 1.