This example tells us that after exercising outdoors on a summer day, you find that your face is flushed and red, your clothes are drenched in sweat. What variable is your body controlling for? What is the stimulus that initiates the negative feedback loop? And in your own words, how do both a red face and sweaty clothes relate to the negative feedback loop in this example? All right.

So let's take these one by one. What is the variable that your body is controlling for? Take a second. You know what it is. Sounds to me like the variable is temperature.

The responses there are classic responses to a change in body temperature. All right. And specifically, what is the stimulus? How is the temperature changing? Well, the stimulus to me sounds like the body is too hot.

The body is too warm. So an increase in body temperature is going to cause these responses. And now let's think specifically how do both these responses relate to the body getting too warm and the negative feedback loop. So we'll start with the red face. All right.

Why do you get a red face when you get too hot? Well, a red face, you're shunting blood to the skin, and we call that vasodilation of the blood vessels to the skin. And that specific word vasodilation, you might need to know it. Check your notes to be sure. So more blood to the skin means that that blood can take the warm body heat and radiate it out, and that will help cool off your body.

Okay. So why do you get sweaty clothes? Well, sweat equals evaporative cooling. When the water in the sweat evaporates off your body, that cools down your body and both the blood to the skin and the sweat that you produce, the evaporative cooling, is going to cool down your body and return the body temperature back to its set position. There we go.