Wound healing is the final process in inflammation at which the architecture and the function of the tissues were repaired after an injury. Basically, before wound healing takes place, inflammation occurs at which it helps to eliminate the injurious agents and if elimination is not possible, inflammation helps limiting the effects caused by the injurious agents. Finally, it prepares the site of injury for healing process.
Picture taken from: http://www.pilonidal.org/aftercare/wound_healing_indepth.php
Inflammation is a very important process where it can dilute, destroy and even neutralize the injurious agents that causes the wound. Without inflammation, the wound would never heal as infections at the site of injury remained. There are two types of inflammation which are acute inflammation and chronic inflammation.
Acute inflammation can be triggered by stimuli such as immune reactions, tissue necrosis, trauma and infections. It is a rapid response towards injury or foreign substances that deliver leukocytes and plasma proteins to the site of injury. Two major components of acute inflammation are vascular changes and cellular events.
• Vascular changes:
Acute inflammation can caused the vasodilation of blood vessels. Vasodilation of blood vessels result in the increased blood flow to the site of injury, thereby causing erythema (redness) and warmth characteristics. Vasodilation and increased blood flow then leads to an increased in intravascular hydrostatic pressure, allowing the fluid (transudate) to flow from the capillaries into the tissues. The fluid then accumulate in the extravascular spaces causing a condition called edema.
• Cellular events:
An important function of inflammatory response is to attract leukocytes to the site of injury thereby activating them so they can carry out the killing and elimination action. The attraction of leukocytes to the site of injury involve 4 different events which are margination, adhesion, emigration and chemotaxis.
Normally, blood flows across the blood vessels through the centre of the lumen. The vasodilation caused by inflammatory response slows down the blood flow and the large leukocytes, which move slower than the small size red cells were pushed out from the axial flow, resulting in the increased leukocytes concentration adjacent to the endothelial cell lining. The process of accumulation of leukocytes at the peripheral of vessels is known as margination.
The adhesion of leukocytes to the endothelial surface is mediated by integrins which appears on the surface of leukocytes, interacting with their subsequent ligands on the endothelial cells. The integrins are usually of low affinity and do not adhere to their ligands unless the leukocytes have been activated by chemokines. Once leukocytes are activated by chemokines, their integrins undergo conformational change and...