Figure 3

Complex dynamical changes in humans at different level of spatial organization. A. Examples of chromosomal alterations (mutations): a) deletion of a tract of DNA; b) duplication of a tract of DNA sequence. B. The progressive changes occurring in the nucleus and cytoplasm that accompany the death of a cell. a) Normal cell; b) The nucleus becomes contracted and stains intensely. The cytoplasm is pinker, showing that it binds eosin (a common histochemical stain) more avidly. c) The nucleus disintegrates, appearing as a more or less central area of dispersed chromatin. This phase is called karyorrhexis. d) All nuclear material has now disappeared (kariolysis) and the cytoplasm stains an intense red colour. C. The final appearance of the liver (a) when it assumes the state of cirrhosis (b). Cirrhosis is the final stage of several pathogenic mechanisms operating either alone or in concert to produce a liver diffusely involved by fibrosis (abnormal extra-cellular matrix deposition) and the formation of structurally abnormal parenchymal nodules. D. Human life: from the embryonic stage of morula (a), through that of foetus (b), to the adult being (c). The times elapsing in the variousdynamical processes exemplified (A-D) are very different (simplified by green bars), ranging from nanoseconds to years. It is interesting to highlight the inverse relationship between the level of anatomical complexity and timescale.