The Pathology Dictionary Team
March 24, 2023

What is inflammation?

Inflammation is the natural response of the body’s immune system to injury, infection, or stress. It is a complex process that involves the release of chemicals from immune cells, blood vessels, and other tissues that help to fight off harmful substances and repair damaged tissues.

What causes inflammation?

Inflammation is caused by the body’s immune system in response to injury, infection, or stress. When tissues are damaged or infected, immune cells release chemical signals such as cytokines, chemokines, and prostaglandins that trigger inflammation. These chemicals cause blood vessels to dilate and become leaky, allowing immune cells and other substances to enter the affected tissues.

Common causes of inflammation include:
  • Infections caused by bacteria, viruses, fungi, or parasites.
  • Physical injuries such as cuts, bruises, and burns.
  • Allergies to foods, pollen, or other environmental factors.
  • Chronic diseases such as arthritis, diabetes, and inflammatory bowel disease.
  • Exposure to environmental toxins, medications, or other chemicals such as stomach acid.
  • Lifestyle factors such as stress, poor diet, lack of exercise, and smoking can also contribute to inflammation.

What are the symptoms of inflammation?

The symptoms of inflammation can vary depending on the location and severity of the inflammation, but they typically include:

  • Redness: The affected area may appear red or discolored.
  • Swelling: The area may become swollen or puffy due to an accumulation of fluid.
  • Heat: The affected area may feel warm to the touch.
  • Pain: Inflammation can cause pain or discomfort, either at the site of the inflammation or in nearby areas.
  • Loss of function: Inflammation can cause a loss of function in the affected area, making it difficult to move or use the affected body part.
  • Fever: Systemic inflammation, which affects the entire body, can cause fever and other flu-like symptoms.

In some cases, inflammation may not produce any noticeable symptoms. However, even in these cases, inflammation can still be damaging to the body over time.

What types of cells contribute to inflammation?

Inflammation is a complex process that involves several different types of immune cells that work together to trigger and regulate the body’s immune response.

Immune cells that contribute to inflammation include:
  • Neutrophils: These are the most common type of white blood cells and are often the first cells to arrive at the site of injury or infection. They are responsible for engulfing and destroying invading pathogens. Neutrophils are often seen in areas of acute inflammation.
  • Macrophages: These are large white blood cells that play a key role in the immune system’s response to infection and inflammation. They are involved in phagocytosis, the process of engulfing and destroying invading pathogens. Macrophages inside tissue are called histiocytes.
  • Mast cells: These white blood cells are involved in the body’s allergic response and are responsible for releasing histamine, a chemical that causes blood vessels to dilate and become more permeable.
  • T cells: These white blood cells help coordinate the immune response. They can either promote or suppress inflammation depending on the situation. T cells play an important role in the fight against viral infections.
  • B cells: These white blood cells are responsible for producing antibodies, which can help to neutralize invading pathogens and prevent them from causing further damage.
  • Eosinophils: These cells are involved in the body’s response to parasitic infections and allergic reactions.
  • Basophils: These white blood cells play a role in the body’s defense against parasitic infections and allergic reactions

What is the difference between acute and chronic inflammation?

Inflammation can be acute, which is a short-term response to injury or infection, or chronic, which is a long-term response that can persist even after the initial injury or infection has been resolved.

Can inflammation cause harm?

While inflammation is typically a protective response, long-standing or chronic inflammation can be harmful and has been linked to a variety of diseases, including arthritis, diabetes, heart disease, and cancer.

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