Page 43 - Textbook of Pathology, 6th Edition

27 CHAPTER 3

Figure 3.5 The cell cycle in mitosis. Premitotic phases are the G 1 , S and G 2 phase while M (mitotic) phase is accomplished in 4 sequential Cell Injury and Cellular Adaptations
stages: prophase, metaphase, anaphase, and telophase. On completion of cell division, two daughter cells are formed which may continue to
remain in the cell cycle or go out of it in resting phase (interphase), the G phase. (CDK = cyclin dependent kinase).
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Target organ stimulation of mitosis occurs under the 5. Immunologic agents
influence of specific hormones which have mitogenic effect 6. Nutritional derangements
on cells of the target organ. 7. Aging
8. Psychogenic diseases
ETIOLOGY OF CELL INJURY 9. Iatrogenic factors
10. Idiopathic diseases.
The cells may be broadly injured by two major ways: In a given situation, more than one of the above etiologic
A. By genetic causes factors may be involved. These are briefly outlined below.
B. By acquired causes
The genetic causes of various diseases are discussed in 1. HYPOXIA AND ISCHAEMIA. Cells of different tissues
Chapter 10. The acquired causes of disease comprise vast essentially require oxygen to generate energy and perform
majority of common diseases afflicting mankind. Based on metabolic functions. Deficiency of oxygen or hypoxia results
underlying agent, the acquired causes of cell injury can be in failure to carry out these activities by the cells. Hypoxia is
further categorised as under: the most common cause of cell injury. Hypoxia may result
1. Hypoxia and ischaemia from the following:
2. Physical agents The most common mechanism of hypoxic cell injury is
3. Chemical agents and drugs by reduced supply of blood to cells due to interruption i.e.
4. Microbial agents ischaemia.