14 topics with concise breakdowns: definitions, key facts, and class questions.
An infectious process is not simply the fact of a microbe entering the body, but a complex set of evolutionarily developed reactions between the macro- and microorganism. In this chapter, we examine how this struggle unfolds: from the entry of the pathogen through the portal of entry to complete recovery or chronization.
This section covers all key links of pathogenesis. You will study microbial pathogenicity factors and the action of bacterial toxins, learn how Toll-like receptors are the first to recognize «foreigners», and analyze in detail the operation of the phagocyte microbicidal system. We consistently examine the conditions and stages of infection, the involvement of the immune and nervous systems, as well as humoral factors of innate immunity. The chapter concludes with the pathophysiological principles of therapy for the infectious process.
Study tip: seminars and exams most frequently ask about the mechanisms of action of exo- and endotoxins, the structure of the macrophage oxygen-dependent system, and the pathogenesis of specific stages of the disease. Pay special attention to the role of Toll-like receptors — this is an absolute foundation for understanding how innate immunity works, which instructors strictly test on.
What is the difference between superinfection and reinfection?
The main difference lies in the timing of re-infection with the same pathogen. In superinfection, it occurs against the background of the ongoing disease (before recovery), whereas in reinfection, it occurs only after the patient's complete clinical recovery.
Which microorganisms participate in commensalism and where do they inhabit?
Opportunistic microorganisms participate in commensalism. Under normal conditions, they are localized as part of the normal intestinal microflora, on the skin and mucous membranes, without harming the macroorganism.
How does pathogenicity differ from virulence?
Pathogenicity is the general genetic characteristic of an entire microbial species (the fundamental ability to cause disease). Virulence is the degree of aggressiveness of a specific strain of that species, which depends on the properties of the microbe itself and host susceptibility.
What is the main pathogenicity factor of gram-negative bacteria during their mass destruction?
When gram-negative bacteria are destroyed, lipopolysaccharides (LPS), which are a component of their outer membrane, are released. The biological activity of this process is entirely determined by the hydrophobic component of LPS — lipid A.
What is the infectious dose of a microorganism in pathophysiology?
This term refers to the strictly minimum number of exclusively viable pathogens necessary for an infectious disease to begin developing in the body. If the number of invading microbes turns out to be below this critical threshold, the disease will not develop, as defense mechanisms will be triggered.
Does the same pathogen always cause the same disease?
No, this depends on the portal of entry. For example, Streptococcus on the tonsils causes tonsillitis, whereas penetration through the skin causes erysipelas or pyoderma.
Master the entire topic in the "Pathophysiology" course
This is a summary. The course covers everything tested in classes and exams.
4,913 pages of study guides on all topics
Assignments and quizzes after every topic — just like in a colloquium