5. Immune Mechanisms In any immune response, cells are damaged through the phagocytic activity of . In cases where there is no pathogen present, the immune response itself is acting to damage normal cells. This type of reaction can be classified into two categories: exogenous and endogenous reactions. During an immune reaction, the body’s immune system attacks antigens in the body’s own cells. This is an reaction. Diseases such as haemolytic anemia and arthritis are autoimmune diseases. An immune reaction, there is an exaggerated response from the immune system to an external antigen that is not harmful to the body. are a common example of an exogenous immune reaction. 6. Genetic Mutation Changes, or mutations, in the genetic makeup of a cell can have three outcomes: If a single nucleotide is changed it is likely that there will be on the cell’s function. If a larger change occurs there may be an or decrease in the function of an enzyme or protein. In some cases, mutation is with survival and necrosis or apoptosis occurs. Any change in the genetic makeup of a cell is passed on to subsequent generations of cells. This means that mutation is heritable. Mutations can occur during the production of zygotes (sperm and eggs), during fertilization, or during the replication of adult cells (somatic mutation). 7. Age Related Injury Damage occurs to cells as they age. In normal cell function, metabolites known as free radicals are created. These molecules have a lone, unpaired electron in the valance shell of one of the atoms. This unpaired electron has an affinity for phospholipids and can disrupt the membrane of the cell and of organelles. Normally free radicals are neutralized by , but as the cell ages peroxisomes are reproduced more slowly and greater damage is done to the cell by free radicals. 8. Nutritional Imbalances Nutrition is essential for the normal function of cells. Certain deficiencies or imbalances can affect the ionic balance of cells, the ability to neutralize free radicals, the formation of coenzymes and cofactors and the ability to build cell structures. Essential nutrients are a group of nutrients that must come from the external environment in order for normal cell function. The essential nutrients include assorted vitamins and minerals as well as an energy source and water. . This is a deficiency in a vitamin or group of vitamins. In horses, there is little incidence of hypovitaminosis, however high-performance horses may not receive sufficient levels of vitamin E from their diets. One type of nutritional imbalance is hypovitaminosis or Hypervitaminosis is an excess of a particular vitamin. Severe hypervitaminosis can lead to vitamin . Again, in a natural diet there is little evidence of hypervitaminosis in horses, but over supplementation of vitamin A and vitamin D occurs.
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