What is the first step described in the four steps of the inflammatory response?

What is the first step described in the four steps of the inflammatory response?

• A. Hyperemia with heat and redness
• B. Increased cell permeability and vasodilation
• C. Pain from swelling
• D. Loss of function

Answer: (A)

The first step in the inflammatory response is hyperemia from vasodilation of the small blood vessels. Dilation of arterioles increases blood flow to the injured area, which produces heat and redness as more warm, oxygenated blood reaches the tissue. This early vascular change sets the stage for later events, such as increased vascular permeability that leads to swelling and, with mediators, pain. Pain from swelling and any loss of function come after the initial vascular response, not at the very start. So describing hyperemia with heat and redness best matches the initial step.

The first step in the inflammatory response is hyperemia from vasodilation of the small blood vessels. Dilation of arterioles increases blood flow to the injured area, which produces heat and redness as more warm, oxygenated blood reaches the tissue. This early vascular change sets the stage for later events, such as increased vascular permeability that leads to swelling and, with mediators, pain. Pain from swelling and any loss of function come after the initial vascular response, not at the very start. So describing hyperemia with heat and redness best matches the initial step.