Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, or damaged cells. Inflammation is a protective mechanism of the organism to remove the injurious stimuli and to initiate the healing process. Inflammation is not a synonym for infection. Infection is caused by an exogenous pathogen, while inflammation is one of the responses of the organism to the pathogen. Without inflammation, wounds and infections would not heal. Chronic inflammation can also lead to different diseases, such as hay fever, atherosclerosis, and rheumatoid arthritis.