The vascular response is the body's immediate reaction to injury or infection, primarily involving blood vessels. When tissues are damaged, the blood vessels in the area constrict to reduce blood loss. This is followed by dilation, which increases blood flow to the affected area, allowing essential nutrients and immune cells to reach the site of injury. During this process, the permeability of blood vessel walls increases, enabling proteins and white blood cells to exit the bloodstream and enter the surrounding tissue. This response is crucial for initiating healing and fighting off potential infections, making it a vital part of the body's defense mechanism.