Pathology is a science that studies the loss of the body's balance . This study permits diagnosis of diseases and hence the appropriate therapy.

Some terms are often used in pathology . For instance , the causes of diseases are called etiology , mechanisms of action are the pathogenesis , the lesions become pathological anatomy and pathophysiology is by that physiological changes are recognized.

There are factors that influence the installation of diseases and it is also relevant in the study of this science . The host-parasite relationships , seasonality, source of infection , modes of transmission , the port enters and the virulence of the pathogenic organism are some of these factors .
 

And after an infection , the body goes through stages which are : incubation period (without clinical manifestations ), prodromal period (with nonspecific signs and symptoms ), state period (with specific signs and symptoms ) and the period of evolution in which the person can progress to healing, to chronicity, for complications and death.

It is when the cell comes in contact with some pathogenic stimulus that it can respond through a process of cell adaptation or by a process of cellular injury . Basically , a cellular adaptation leads to changes in volume and cell differentiation , but this topic is best discussed in class growth changes . Meanwhile , the lesions can be of two types : reversible and irreversible and this theme is also in a class of its own. The lesions can be classified as non-lethal, lethal, interstitial changes, disturbances of blood and lymph circulation and changes in innervation.