Final answer:
On a hot day, homeostasis maintains body temperature through sweating and dilation of dermal blood vessels, which allow the body to cool down by increasing blood flow to the surface and evaporating sweat.
Step-by-step explanation:
How Homeostasis Regulates Body Temperature on a Hot Day
When you go for a long walk on a hot day, homeostasis keeps your body at a stable internal temperature through several mechanisms. An example of homeostasis in action is sweating to cool down. As your body temperature rises, your sweat glands increase their output of fluid. This sweat evaporates from the skin's surface, removing heat and cooling your body down. Other processes such as the dilation of dermal blood vessels also help by allowing more blood to flow to the skin's surface, releasing excess heat into the environment.
In the context of this situation, options such as shivering to generate heat or constriction of blood vessels, which help conserve heat, are not relevant since your body is trying to release heat, not conserve it. Similarly, while an increased heart rate does occur to help circulate blood and therefore heat to the skin, it is primarily the increased sweat output and the dilation of blood vessels that directly contribute to thermal regulation on a hot day.