- •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?
27.19 What reasons and mechanisms of development of a sinus tachycardia and bradycardia?
A sinus tachycardia and a bradycardia concern to group normothopical arhythmias, connected with infringements of function of automatism.
Ability to automatic formation of impulses depends on the cells located in spending system of heart (Ó-cell) in which occurs spontaneous slow depolarization of a cellular membrane during diastole. As a result, after achievement of the certain critical level, there is a potential of action. Frequency of generation of impulses depends from maximal diastolic potential of these cells, a level of that critical potential on a membrane after which there is a potential of action, and speed diastolic depolarization.
Change of a maximal level of a diastolic potential, critical potential or speed diastolic depolarization in this or that party conducts to change of frequency of generation of impulses or for occurrence of other sources impulsation if these changes arise in other sites of heart capable to excitation and lead to occurrence in them of potentials of action.
At reduction of a maximal level diastolic potential of cells sinus-auricular node, at approach it of threshold potential or increase in speed slow diastolic depolarization impulses are generated more often, the tachycardia develops. It is observed under influence raised of temperature of bodies, stretching of area sinus-auricular node, sympathetic mediator.
On the contrary, reduction of speed slow diastolic depolarization, hyper polarization in diastole and a distance of critical threshold potential as it is observed at irritation of a wandering nerve, are accompanied by delay of generation of impulses, and consequently, and reduction of heart - a bradycardia. Fluctuations of a tone of a wandering nerve during the certificate of breath can cause respiratory arhythmia (increase of palpitation at a breath, delay - at an exhalation). Respiratory arhythmia happens at children in norm, but occasionally it can be observed at adults.