Final answer:
Swelling during inflammation occurs due to increased vascular permeability, which allows fluid to move from the blood into the surrounding tissue, leading to edema. This process is mediated by inflammatory substances such as histamine, and it facilitates the arrival of immune cells to the affected area.
Step-by-step explanation:
Inflammation is a complex biological response to harmful stimuli such as pathogens, damaged cells, or irritants. One of the classic signs of inflammation is swelling, also known as edema. Swelling during inflammation is due to increased vascular permeability. When tissues are injured, inflammatory mediators like histamine, leukotrienes, and prostaglandins are released. These substances induce vasodilation, which increases blood flow to the affected area, and make the capillary walls more permeable. Consequently, fluid leaks out into the interstitial space, leading to swelling. This response allows immune cells, such as white blood cells, to reach the site of injury or infection to promote healing. Vasodilation and increased vascular permeability combined contribute to the redness, warmth, and pain often associated with inflammation.
This inflammatory response is the body's mechanism to initiate the healing process. Acute inflammation is typically a short-term response, while chronic inflammation can lead to further tissue destruction and is characteristic of autoimmune diseases like rheumatoid arthritis. Moreover, the swelling presses against nerve endings, which contributes to the sensation of pain. Pain can be reduced through the use of NSAIDs that inhibit the synthesis of prostaglandins, chemicals that also facilitate pain and inflammation.