Question

The cardinal signs of inflammation include redness (rubor), heat (calor), swelling (tumor) and pain (dolor). (10 points)

• What chemical mediators are released during inflammation (in response to tissue injury)?
• What occurs to cause “tumor” and “dolor”?
• What are the physiological benefits of the inflammatory response?

Answer 1

An inflammation is a nonspecific defense reaction produced in response to a tissue injury. The inflammatory response is caused by the chemical agents known as mediators formed and released during the tissue damage. The mediators of inflammation are two types called the cell derived mediators and plasma derived mediators. The cell derived mediators such as mast cells are found throughout the connective tissues in the body. The cytoplasm is filled with granules containing histamine and other chemicals that mediators of the inflammatory process.

The histamine is a Vasodilator that can dilate the blood vessels. Blood platelets contain histamine and other inflammatory mediator called serotonin. It is released when the platelets adhere to collagen the fragments of the damaged tissue. A group of other cell derived mediators are called prostaglandins. Leukotrienes are a group of similar compounds. All these are biologically active compounds synthesized by arachidonic acid present in the cell membrane in response to inflammation and intensify the process. The bradykinins are a group of mediators produced by a protein concerned with blood coagulation and activated by the tissue injury.

The inflammatory reaction is characterized by heat (calor), redness (rubor), tenderness, swelling (tumor) and pain (dolor). The warmth and redness is increased at the inflamed tissue is called by dilation of capillaries and the flow of blood is slow down in the vessels. Swelling is resulted due to extravasation or leakage of plasma from dilated blood vessels and increases the volume of fluid in the inflamed tissue. The tenderness and pain next to irritation caused due to sensory nerve endings at the site of injury and inflamed tissue.

The inflammatory reaction results in producing both the local and systemic effects. The local effects include the dilation or expansion of blood vessels and increase the vascular permeability. The white blood cells or leukocytes accumulate at the site of injury. The cells adhere to vascular endothelium and exert the pressure on the walls of vessels to migrate to the area of tissue damage. The accumulation of white blood cells prevent the invasion of microbes and infection.