6 topics with concise breakdowns: definitions, key facts, and class questions.
This section focuses on the ability of living systems to restore lost structures and the regular final stages of ontogeny. Here we examine the fine line between maintaining life through cell renewal and the inevitable processes of decline.
The material covers two major blocks. The first is types of restoration: physiological and reparative regeneration, the specifics of these processes in vertebrates and humans, as well as pathological regeneration (dysregeneration). The second block covers the biology of aging and death as the natural conclusion of the life cycle of the cell and the organism as a whole.
During practical classes and exams, instructors most frequently ask to compare physiological and reparative regeneration, provide clinical examples of pathological regeneration (e.g., keloid scar formation), and explain key genetic theories of aging, including the Hayflick limit and telomere shortening.
Is there a single theory that fully explains the mechanisms of aging?
No, there is no single unifying theory of aging in modern biology. The process is a complex interplay of interrelated genetic, regulatory, and trophic shifts.
What is the main difference between clinical and biological death?
The main difference lies in reversibility. In clinical death, respiration and heartbeat have stopped, but cellular metabolism remains intact, which allows for patient resuscitation. In biological death, irreversible chemical chaos and autolysis occur.
What is the main difference between physiological and reparative regeneration?
Physiological regeneration compensates for cell loss resulting from normal, routine activity. Reparative regeneration is triggered exclusively to restore tissue integrity following damage.
What is the fundamental difference between homomorphosis and heteromorphosis?
In homomorphosis, a structure identical to the lost one regenerates. In heteromorphosis, atypical organs or tissues not matching the original ones are restored at the injury site.
Why do deep skin wounds leave a scar?
This is because the proliferation rate of loose connective tissue is much higher than that of epithelium. Connective tissue rapidly fills the wound, forming a fibrous scar, which is an example of incomplete compensation.
What happens to heart tissue after a myocardial infarction?
The focus of necrosis cannot be repaired by muscle cells and fills with connective tissue, forming a scar. Surviving cardiomyocytes compensate for the loss through hypertrophy—their sarcoplasm volume, number of nuclei, and myofibrils increase.
Master the entire topic in the "Biology" course
This is a summary. The course covers everything tested in classes and exams.
3,793 pages of study guides across all topics
Assignments and quizzes after every topic — just like in a colloquium