- •27. Pathophysiology of heart.
- •27.1. What is insufficiency of circulation of the blood?
- •27.2 What is result of the insufficiency of circulation of the blood for organs, tissues and organism in whole?
- •27.3 What is cardiac insufficiency?
- •27.4 What is the classification of cardiac insufficiency?
- •27.5 Give short characteristic of different pathogenic variants of cardiac insufficiency.
- •27.6. What types of heart’s overloading can cause the development of cardiac insufficiency?
- •27.7. What mechanisms can provide the compensation of heart during the effect of the increased leading on it?
- •27.8. What is the essence of the heterometric mechanism of the compensation of the heart?
- •27.9. What is the essence of the homeometric mechanism of the compensation of the heart?
- •27.10. What is the essence of the chronoinotropic mechanism of the compensation of the heart?
- •27.11. What is the roll of catecholamines in the realization of mechanisms of urgent compensation of the heart?
- •27.12. Name the variants of prolonged adaptation of the heart to the effect of ladings.
- •27.13. What mechanism lay on the base of development of the heart’s hypertrophy?
- •Hypertrophy
- •27.14. What phases can be distinguished in the process of development of compensatory hypertrophy of the heart? Give their characteristics.
- •27.14 What strategy allocate during development compensatory hypertrophies of heart? Give their characteristic.
- •27.15 What features of the hypertrophied heart are the precondition of its development of decompensation?
- •27.16. What can cause the development of the myocardial insufficiency of heart?
- •27.17. What is hearts arhythmy? How does they classified?
- •27.18. What arhythmias of heart can be a result of infringement of function of automatism?
- •27.19 What reasons and mechanisms of development of a sinus tachycardia and bradycardia?
27.9. What is the essence of the homeometric mechanism of the compensation of the heart?
Homeometric mechanism is the urgent mechanism of the compensation of the heart to the effect of the leadings by resistance. Its essence is in increase of the contractilites’ power is conditions of resistance to expulsion of the blood. It is shower now, that the essence of this mechanism as heterometric also the Frank-Starlong law, that is the increase of the starting length of the myocardium fibers and connected with in the increase of the final diastolic pressure.
The formation of the homeometric mechanism derives in such sequence. During the increase of the resistance to expulsion of the blood the percussion volume falls abruptly as a result of what the final diastolic volume of ventricles increases. As the coming of blood into ventricles continues to stay the same so in the next cycle of heart’s contractility the final diastolic volume increases. And this according to Francs-Starling law leads to an increase of the heart contractilities’ power.
Such changes of cardiodynamic indicators are characteristic for the геометрического mechanism:
a) an increase of the final diastolic volume;
b) an increase of the final diastolic volume because of the primary increase of the previous indicator and not because of the increase of inflow of the blood as during the homeometric mechanism;
c) percussion and so minute volumes because of the increase of the heart contractilities’ power they (volumes) stay on the same level in spite of the increase of resistance to expulsion of the blood.
During the геометрическом mechanism the tension of the myocardium muscular fibers increases and the same time their length does not change. As a result we have a name of the compensatory mechanism – homeometric.
27.10. What is the essence of the chronoinotropic mechanism of the compensation of the heart?
Chronoinotropic mechanism (“phenomenon of stears”, Bovdich phenomenon) is one of the urgent mechanisms of the heart’s compensation to the effect of increased leadings. Its essence is that during the increase of the frequency of the heart’s contractility the power of its contractility also increases. During this the time of myocardium relax simultaneous reduces and it promotes to quickly filling of the heart’s ventricles with blood.
The basis of the chronoinotropic mechanism is the increase the enlistment of calcium ions into sarcoplasm of cardiomiocytes during the action potential, find their total duration during the tachycardia increases. The increase of concentration of the calcium ions in sarcoplasm leads to the increase of the quantity of the organizing calcium-troponin complexes and as a consequence to the increase of the muscular fibers contractility power.
Such changes of cardiodynamic indicators are characteristic for the chronoinotropic mechanism:
a) the percussion volume increases (during the leading by volume) and stays permanent (during the leading by resistance). As a result of increase of the heart contractility’ frequency the minute volume of the heart also increases;
b) the final diastolic volume values in the inflow of the blood to the heart is permanent or stays without changes is the inflow of the blood increases;
c) the final diastolic volume reduces