An Inside Look at Inflammation - Pharmacology

Inflammation is the body’s protective response to injury to tissues. Injury causes the release of three chemicals that stimulate a vascular response that force fluid and white blood cells to flow to the site of the injury. Stimulated nerve endings signal the brain that there is an injury.

These chemicals are

  • Histamines. This chemical works to bring more blood and lymph fluid to the site of the invasion.
  • Kinins. These are blood plasma proteins that influence smooth muscle contractions, increase blood flow throughout the body, increase the permeability of small capillaries, and stimulate pain receptors.
  • Prostaglandins. They work as chemical messengers. They do not move but work right in the cell where they are synthesized. They are synthesized in every cell in the body. These chemicals activate the inflammatory response and produce pain and fever. They are produced in response to the white blood cells that flow to the area of injured tissue.

The injured tissue becomes red, swollen, warm and loses its normal function. These, along with pain, are the five cardinal signs of inflammation. It is important not to confuse inflammation and infection because they are not the same.

Only a small percentage of inflammation is caused by infection from micro organisms. Trauma, surgery, extreme heat or cold, electricity, and caustic chemicals cause most inflammation.

Inflammation occurs in two phases.


The vascular phase occurs 10 to 15 minutes after the tissue is injured. It is during this phase that blood vessels dilate (vasodilation) and become more permeable, enabling fluid and white blood cells to leave the plasma and flow to the injured tissue.


The delayed phase occurs when the injured tissue is infiltrated by white blood cells. White blood cells (also called leukocytes or immune cells) are components found in the blood. They are also found in the spleen, the lymphatic system, and other tissues. They help defend the body against infectious disease and foreign material as part of the immune system. The three main types of leukocytes (white blood cells) are granulocytes (neutrophils, basophils, and eosinophils), lymphocytes (B-cells, T-cells, and natural killer cells), and monocytes.

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