The word inflammation is derived from the Latin word- inflammare which means to set on fire. It is a part of a complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants.
The process is an attempt by the body to get rid of the injurious stimuli and to begin the healing process.
Acute and Chronic Inflammation
Acute inflammation is the initial response of the body to harmful stimuli and is achieved by the increased movement of plasma and leukocytes (especially granulocytes ) from the blood into the injured tissues.
A cascade of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells within the injured tissue. Prolonged inflammation, known as chronic inflammation, leads to a progressive shift in the type of cells present at the site of inflammation and is characterized by simultaneous destruction and healing of the tissue from the inflammatory process.
Here are the five cardinal signs of acute inflammation. These signs are present in the area where inflammation is active.
- Dolor (pain)
- Calor (heat)
- Rubor (redness)
- Turgor (swelling)
- Functio laesa (loss of function)
The first four signs are called classical signs and were described by Celsus while loss of function was added later by Galen.
Acute inflammation is of sudden onset and quickly increases in severity, lasts for a few days generally but may persist for few weeks.
It starts rapidly (rapid onset) and quickly becomes severe. Signs and symptoms are only present for a few days, but in some cases may persist for a few weeks.
Inciting stimuli is generally a pathogen or injury. Acute inflammation is conducted by neutrophils, basophils, eosinophils, and monocytes. Primary mediators are eicosanoids and vasoactive amines.
Acute appendicitis is an example.
Chronic inflammation is long-term, can last for months and years. This generally occurs when the body cannot eliminate the stimulus, there is an autoimmune phenomenon or presence of a chronic irritant.
It is caused by generally non-degradable pathogens that persist, some viral infections, foreign body or hyperimmune system reactions.
Major cells involved are macrophages, lymphocytes, plasma cells, and fibroblasts. Primary mediators are reactive oxygen species, hydrolytic enzymes, IFN-γ and other cytokines, growth factors.
Chronic inflammation causes tissue destruction, fibrosis, and necrosis. Asthma is an example of chronic inflammation.
NSAIDs or non-steroidal anti-inflammatory drugs which reduce inflammation are taken to control pain caused by inflammation. They block cyclooxygenase enzyme and prostaglandins which cause inflammation.
Other classes of drugs are steroids which suppress the inflammation.