Question

Overview

Inflammation is the body’s way of reacting to the presence of something that sets it out of balance, such as a bee sting or a pathogenic infection. Inflammation can occur in an acute or chronic fashion as well as in a localized or systemic fashion. Although inflammation can occur quite quickly, there is actually a complex set of biochemical steps involved in the inflammatory response.

Instructions

Create a flowchart covering the body’s inflammatory response by beginning with a specific event of your choice (sprained ankle) that would initiate inflammation. In your flowchart, include the timeline of events that would occur internally and externally to the body, the mediators of the inflammatory response, what factors could influence the outcome, and how could it be treated.

When you have finished your flowchart, think about how you would explain the process to a friend, family member, or even a small child. Write a summary of the flowchart explaining the process in your own words.

Answer 1

b) Inflammatory response plays a critical role in immunity. When tissues are damaged, the inflammatory response is initiated, and the immune system becomes mobilized. The immune cells of the innate immune system (i.e., neutrophils and eosinophils) are the first recruited to the site of tissue injury or damage via blood vessels and lymphatic system, followed by macrophages.

If the damage occurs near the surface of the skin, redness and swelling may be visible. Pain and warmth are also symptoms of inflammation.

After tissue injury, damaged cells release inflammatory chemical signals that stimulate local vasodilation, the widening of the blood vessels. Increased blood flow results in apparent redness and heat. In response to injury, mast cells present in tissue degranulate, releasing the potent vasodilator histamine. Increased blood flow and inflammatory mediators recruit white blood cells to the site of inflammation. The endothelium lining the local blood vessel becomes “leaky” under the influence of histamine and other inflammatory mediators allowing neutrophils, macrophages, and fluid to move from the blood into the interstitial tissue spaces. The excess liquid in tissue causes swelling, more properly called edema. The swollen tissues squeezing pain receptors cause the sensation of pain. Prostaglandins released from injured cells also activate pain neurons. Non-steroidal anti-inflammatory drugs (NSAIDs) reduce pain because they inhibit the synthesis of prostaglandins. High levels of NSAIDs reduce inflammation. Antihistamines decrease allergies by blocking histamine receptors and as a result the histamine response.

After containment of an injury, the tissue repair phase starts with removal of toxins and waste products. Clotting (coagulation) reduces blood loss from damaged blood vessels and forms a network of fibrin proteins that trap blood cells and bind the edges of the wound together. A scab forms when the clot dries, reducing the risk of infection. Sometimes a mixture of dead WBCs and fluid called pus accumulates in the wound.

As healing progresses, fibroblasts from the surrounding connective tissues replace the collagen and extracellular material lost by the injury. Angiogenesis, the growth of new blood vessels, results in vascularization of the new tissue known as granulation tissue. The clot retracts pulling the edges of the wound together, and it slowly dissolves as the tissue is repaired.this is known as wound healing.