What exactly is inflammation?

Inflammation is a reaction caused by damage to living tissues in the body. The inflammatory response is a defense mechanism that evolved in higher organisms, such as humans, to protect them from serious infection and injury.

Its purpose is to localize, eliminate the harmful agent and remove damaged tissue components so that the body can begin to heal itself.

The response consists of changes in blood flow, increased permeability of blood vessels, and the directing of fluids, proteins, and white blood cells (leukocytes) to the site of tissue damage.

An inflammatory response that lasts only a few days is called acute inflammation, and an inflammatory response that lasts longer is known as chronic inflammation.

Acute Inflammation

Although acute inflammation is ultimately beneficial to the body, it often causes unpleasant sensations, such as sore throat pain or itching at the site of an insect bite.

Discomfort is usually temporary and goes away when the inflammatory response has done its job. But in some cases the inflammation itself can cause harm to the person.

When regulatory mechanisms of the inflammatory response are defective or the ability to clear damaged tissue is impaired for some reason, tissue destruction can occur.

In other cases, an inappropriate immune response can lead to a prolonged and harmful inflammatory response.

Examples include certain allergic inflammations or hypersensitivity to an environmental agent, such as pollen, which normally poses no threat to the individual but stimulates inflammation and autoimmune responses, in which chronic inflammation is triggered as the body’s immune response against a person’s own tissues .


Factors that can stimulate inflammation include microorganisms, physical agents, chemicals, inappropriate immune responses, and tissue death.

Infectious agents such as viruses and bacteria are one of the most common factors triggering inflammatory processes. Viruses lead to inflammation by entering body cells and destroying them.

Bacteria, on the other hand, release substances called endotoxins, which can initiate inflammation. Physical trauma, burns, radiation, frostbite, and more can damage tissues and also lead to inflammation.

Inflammation can be caused by various corrosive chemicals such as acids, bases, and oxidants. As mentioned above, a malfunction of immunological responses can cause an inappropriate and harmful inflammatory response to the human body.< /p>

Inflammation can occur when tissues die from a lack of oxygen or nutrients – a situation that is often due to a loss of blood flow to the area.


The four main signs of inflammation are redness, warmth, swelling, and pain. The redness is caused by dilation of the small blood vessels in the area of ​​the injury.

Heat is the result of increased blood flow to the area and is usually felt in peripheral parts of the body such as the skin. The swelling, called edema, is mainly due to the accumulation of fluid outside the blood vessels.

Pain associated with inflammation is the result of tissue disruption in an area caused by swelling.

Healing and Repair

During the healing process, damaged cells must be repaired. Different types of cells differ in their ability to regenerate.

Some cells, such as epithelial cells, regenerate easily and quickly, while others, such as liver cells, do not normally reproduce but may be stimulated to do so after certain injuries occur.

However, there are other types of cells that are completely incapable of regeneration. For regeneration to be successful, it is also necessary that the structure of the tissue is simple enough to regenerate.

For example, uncomplicated structures such as flat skin are easy to restore, but the complex structure of a gland is not. In some cases, the inability to reproduce an organ in its original form can result in to illness.

This is the case with cirrhosis of the liver, in which repair of damaged tissues can progress to the construction of abnormal structures that can lead to hemorrhage and death.

When the damaged tissues have suffered significantly or the tissue structure cannot be successfully regenerated, this results in the formation of a fibrous scar.

In the repair process, new blood vessels and cells called fibroblasts are created. The volume of connective tissue is usually less than that of the tissue it replaces, which can cause some organs to shrink and distort. The most drastic cases of scarring occur in response to severe burns or trauma.

Pus accumulation

The process of pus formation, called suppuration, occurs when the agent that provokes the inflammation is difficult to remove from the body.

Pus is a viscous fluid that consists primarily of dead and dying neutrophils and bacteria, cellular debris, and fluid leaked from blood vessels. The most common cause of pus accumulation is infection with pus-forming bacteria such as Staphylococcus and Streptococcus.

Pus begins to collect in tissue surrounded by a membrane, which leads to the formation of a structure called an abscess. Because an abscess is almost inaccessible to antibodies and antibiotics, it is very difficult to treat.< /p>

Sometimes it is necessary to make a surgical incision to drain the dirt and remove it. Some abscesses, such as boils, may burst on their own. The cavity that remains after the abscess shrinks and the tissue is gradually replaced by new and healthy tissue.

Chronic inflammation

If the agent causing the inflammation cannot be eliminated or if there is some interference with the healing process, the acute inflammatory response can progress to a chronic phase.

Repeated bouts of acute inflammation can also lead to chronic inflammation. The physical symptoms, duration, and effects of chronic inflammation vary depending on the cause and the body’s ability to alleviate the condition.

What can cause chronic inflammation?

chronic inflammation can be caused by infectious organisms that are able to resist host defenses and continue to live in the tissue for an extended period of time.

These organisms are tuberculosis, fungi, protozoa and some parasites. Other inflammatory agents are materials foreign to the body that cannot be removed by phagocytosis or enzymatic breakdown.

These include substances that can be inhaled, such as quartz dust, and also materials such as metal or sawdust.

When the immune system is oversensitive, the autoimmune reaction can turn into chronic inflammation. Autoimmune reactions can lead to some well-known chronic inflammatory diseases such as rheumatoid arthritis.

A hallmark of chronic inflammation is the infiltration of the site of tissue by macrophages, lymphocytes and plasma cells.

Macrophages are the main cells involved in chronic inflammation and produce many effects that contribute to the development of tissue damage with subsequent functional disorders.

Granulomatous inflammation is a separate type of chronic inflammation. It is characterized by the formation of granulomas, which are small collections of modified macrophages and are usually surrounded by lymphocytes.

A classic example of granulomatous inflammation is tuberculosis. It forms granulomas called tubercles. Granulomas can usually occur from fungal infections. They are found in schistosomiasis, syphilis and rheumatoid arthritis.

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