fluid and white blood cells to flow to the site of the injury. Stimulated nerve end-
ings 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 con-
tractions, increase blood flow throughout the body, increase the perme-
ability 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 func-
tion. 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 chem-
icals cause most inflammation.
Inflammation occurs in two phases.VASCULAR PHASE
The vascular phase occurs 10 to 15 minutes after the tissue is injured. It is dur-
ing this phase that blood vessels dilate (vasodilation) and become more perme-
able, enabling fluid and white blood cells to leave the plasma and flow to the
injured tissue.DELAYED PHASE
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(^198) CHAPTER 12 Inflammation