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Immunity can be acquired either actively or passively. Immunity is acquired actively when a person is exposed to foreign substances and the immune system responds. Passive immunity is when antibodies are transferred from one host to another. Both actively acquired and passively acquired immunity can be obtained by natural or artificial means.
He further formalised the theory in his 1959 book The Clonal Selection Theory of Acquired Immunity. He explained immunological memory as the cloning of two types of lymphocyte. One clone acts immediately to combat infection whilst the other is longer lasting, remaining in the immune system for a long time and causing immunity to that antigen.
Adaptive (or acquired) immunity creates an immunological memory leading to an enhanced response to subsequent encounters with that same pathogen. This process of acquired immunity is the basis of vaccination. Dysfunction of the immune system can cause autoimmune diseases, inflammatory diseases and cancer.
In particular, if the distribution of survivor number turns out to decay more like a power law than like an exponential, then we can conclude with high statistical likelihood that Darwinian scenario is true. This is a rough overview of the Luria–Delbrück experiment. (Section 4.4 [1])
Innate immune memory (also called trained immunity) is neither antigen-specific nor dependent on gene rearrangement, but the different response is caused by changes in epigenetic programming and shifts in cellular metabolism. Innate immune memory was observed in invertebrates as well as in vertebrates. [4] [5]
The following outline is provided as an overview of and topical guide to immunology: . Immunology – study of all aspects of the immune system in all organisms. [1] It deals with the physiological functioning of the immune system in states of both health and disease; malfunctions of the immune system in immunological disorders (autoimmune diseases, hypersensitivities, immune deficiency ...
Adoptive immunity acts in a host after their immunological components are withdrawn, their immunological activity is modified extracorporeally, and then reinfused into the same host. [ 1 ] [ 2 ] This process in its former part is analogous to adoption: a child is once adopted out from their home, grown up, and then returned to their home of birth.
Evolutionary progress as a tree of life. Ernst Haeckel, 1866 Lamarck's two-factor theory involves 1) a complexifying force that drives animal body plans towards higher levels (orthogenesis) creating a ladder of phyla, and 2) an adaptive force that causes animals with a given body plan to adapt to circumstances (use and disuse, inheritance of acquired characteristics), creating a diversity of ...