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 perfomance it works more intensively: heart contractioin freaquency and blood stream velocity increase) influences on respiration system.

2) Exteroreceptive 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. These 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 increasung 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 exists 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 dissotiation 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 appears in 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 mentionned 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 these 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 mentionned 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 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).

Thus, at the end of our lecture we must to remember you that healthy breathing – is nasal, as slow and seldom as possible, with its lack in course of inspiration and, especially, after it. While prolonging the inspiration, we stimulate vegetative nervous system sympathetic part work with all following consequences. While prolonging the expiration, we carry carbonic acid in blood more and longer that positively influences on blood vessels tone (decreases it) will all following consequences. Due to this oxygen under such situation can come in the farthest microcirculative vessels preventing disorders of their function and development of many diseases. Correct breathing – is a prevention and treatment of big group of diseases not only of respiratory system but also of other organs and tissues! Breath for enjoy!