Acute inflammation – 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.
Examples of diseases, conditions, and situations which can result in acute inflammation include: acute bronchitis, infected ingrown toenail, sore throat from a cold or flu, a scratch/cut on the skin, exercise (especially intense training), acute appendicitis, acute dermatitis, acute tonsillitis, acute infective meningitis, acute sinusitis, or a blow.
Chronic inflammation – this means long-term inflammation, which can last for several months and even years. It can result from:
- Failure to eliminate whatever was causing an acute inflammation
- An autoimmune response to a self antigen – the immune system attacks healthy tissue, mistaking it (them) for harmful pathogens.
- A chronic irritant of low intensity that persists
Examples of diseases and conditions with chronic inflammation include: asthma, chronic peptic ulcer, tuberculosis, rheumatoid arthritis, chronic periodontitis, ulcerative colitis and Crohn’s disease, chronic sinusitis, and chronic active hepatitis.
Our infections, wounds and any damage to tissue would never health without inflammation – tissue would become more and more damaged and the body, or any organism, would eventually perish.
However, chronic inflammation can eventually cause several diseases and conditions, including some cancers, rheumatoid arthritis, atherosclerosis, periodontitis, and hay fever. Inflammation needs to be well regulated.
What happens during acute inflammation?
Within a few seconds or minutes after tissue is injured, acute inflammation starts to occur. The damage may be a physical one, or might be caused by an immune response.
Three main processes occur before and during acute inflammation:
- Arterioles, small branches of arteries that lead to capillaries that supply blood to the damaged region dilate, resulting in increased blood flow
- The capillaries become more permeable, so fluid and blood proteins can move into interstitial spaces (spaces between cells).
- Neutrophils, and possibly some macrophages migrate out of the capillaries and venules (small veins that go from a capillary to a vein) and move into interstitial spaces. A neutrophil is a type of granulocyte (white blood cell), it is filled with tiny sacs which contain enzymes that digest microorganisms. Macrophages are also a type of white blood cells that ingests foreign material.
When our skin is scratched (and the skin is not broken), one may see a pale red line. Soon the area around that scratch goes red, this is because the arterioles have dilated and the capillaries have filled up with blood and become more permeable, allowing fluid and blood proteins to move into the space between tissues.