Final answer:
Mast cells release histamine, leading to inflammation characterized by swelling, redness, and pain known as edema. NSAIDs and antihistamines are used to treat the symptoms by inhibiting prostaglandins and blocking histamine receptors respectively.
Step-by-step explanation:
When tissue injury occurs, the body responds through an inflammation process largely mediated by mast cells found in connective tissues. These mast cells release histamine and heparin upon being damaged or irritated. Histamine is a potent vasodilator that increases blood flow, leading to the classic signs of inflammation such as redness, heat, and swelling, which is more accurately termed edema. The excess fluid in the tissues causes the swelling and contributes to pain sensation by stimulating pain receptors. Additionally, prostaglandins released from injured cells activate pain neurons. Therapeutic agents like NSAIDs can reduce pain and inflammation by inhibiting prostaglandins synthesis, and antihistamines block histamine receptors, thereby mitigating the histamine response to allergens.