Normal homeostasis is very important for fluid and electrolyte balance, performing normal homeostatic function. Any derangement in normal homeostasis will lead to different medical problems including emergencies. This chapter deals with homeostatic derangements like thrombosis, embolism, infarction, edema, hyperemia and congestion. Etiology, pathogenesis, clinical implications, fate or outcome of these conditions are briefly and meticulously described here. Myocardial infarction (MI): it gross and microscopic features, etiology, clinical features, complications, cardiac markers for its diagnosis, cardiac enzymes and complications of MI and are also described.