Final answer:
The initial stage of the inflammatory response is marked by redness, swelling, warmth, pain, and possible loss of function, which are caused by increased blood flow and immune activity at the site of infection or injury.
Step-by-step explanation:
The first stage of the inflammatory response, also known as local infection, is characterized by several signs and symptoms designed to fight off the invading pathogens and begin the healing process. These signs and symptoms include redness, swelling, warmth, pain, and sometimes loss of function. These are the result of increased blood flow to the affected area, the accumulation of fluids, and the migration of immune cells such as leukocytes to the area of injury or infection. With the dilation of blood vessels and the increased permeability of capillaries, white blood cells and plasma move into the tissues, causing the symptoms associated with the inflammatory response.
Notably, Cornelius Celsus, as early as the first century AD, documented the four cardinal signs during the Roman Empire. Fever, while a systemic response, is another sign that can be associated with inflammation, particularly if the inflammation is widespread or severe.
Inflammation serves as a protective mechanism initiated by the body’s innate immune system to prevent the spread of infection and to start tissue repair processes. It is an important part of the body’s second line of defense, drawing increased blood flow and immune cells to the site of injury or infection.