CHAPTER TWO: CAUSES OF CELLULAR INJURY
Definitions
Disease – ______________________________________________________________________
Immunity – ____________________________________________________________________
Mutation– _____________________________________________________________________
Heritable – _____________________________________________________________________
Endotoxin – ____________________________________________________________________
Exotoxin – _____________________________________________________________________
Ectoparasite – __________________________________________________________________
Nematode – ___________________________________________________________________
Exogenous – ___________________________________________________________________
Endogenous – __________________________________________________________________
Introduction Cells respond to stress by
. If the cell’s ability to adapt is exceeded by external forces, changes take place in the cells that are unrelated to the normal function of the cell. Some changes are reversible once the external stress is removed while other cellular changes are irreversible, and ultimately lead to necrosis of the affected cell. A cell’s response to a pathogen is partially determined by the virulence, dose, intensity and duration of exposure to the pathogen, as well as by the state of the cell itself. Factors such as nutrition, blood supply, general health and genetics have an influence on the cell’s ability to adapt and resist disease. Generally, tissues that are in good health, that have access to a complete array of nutrients, and have an extensive blood supply resist disease better than tissues without these assets. The influence of genetics is less well defined, however certain individuals tend to be resistant to particular pathogens while other individuals are more susceptible. The relation between genetics and immunity is strengthened when we consider that certain diseases are more prevalent in particular species or breeds, while other species or breeds are resistant to that pathogen.
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