An inflammation is the immune response of the organism, its tissue and blood vessels to damaging irritations.

The classical five local cardinal symptoms are described by the following Latin terms:

1. Rubor (“reddening”: caused by hyperaemia, i.e., increased blood circulation);
2. Calor (“heating”: caused by increased metabolic activity and hyperaemia);
3. Tumor (“swelling” of tissue or oedema caused by a washout of blood serum);
4. Dolor (“pain”: caused by tissue tension, pressure on nerve endings and inflammation products)
5. Functio laesa (“functional disorder”: caused by pain or swelling)

An inflammation could be triggered by:

• Mechanical factors (pressure, injury, foreign bodies)
• Physical irritation (radiation, heat, cold)
• Chemical materials (solutions, acids)
• Micro-organisms (bacteria, viruses, fungi)
• Bacterial toxins
• Necrotic tissue

Reddening (“rubor”) is caused by increased blood circulation. This results in a rise of body temperature (“calor”) at this point and the supply of nutrients, oxygen and antigens (e.g., antibodies and immunocompetent cells) is increased. This enables direct combat against inflammation triggering factors at the site. The swelling (“tumor”) is created by a collection of liquids in the tissue (oedema), which predominantly consists of blood plasma. The pressure of this oedema on nerve endings and biochemical pain agents cause pain (“dolor”). Due to the local cell and circulation dysfunction, the affected tissues cannot fulfil their function at all or only insufficiently (“functio laesa”).

The inflammation goes hand in hand with vascular dilation and the release of neutrophile granulocytes and monocytes by the permeable vessel walls. Special lymphocytes form specific antibodies against the inflammatory irritation. If local reaction to the triggering irritation is not sufficient, the entire organism will react, which is predominantly displayed in the increase of body temperature (fever), increased pulse rate, reduced physical capacity and an increase in white blood corpuscles.