This example asks us to identify the components of a negative feedback loop. Alright. So you stand up quickly, causing your blood pressure to fall, and you feel light-headed. Your pulse begins to increase, raising your blood pressure. After a moment, you feel fine.

Using a diagram below, first identify the stimulus and the response, then label the receptor, control center, and effector. Okay. So it shows this picture of a woman here. We can see her blood vessels, her heart, and her brain, and it looks like there is a loop going. It starts at the heart, and an arrow goes up to the brain stem and then back down to the heart.

So first off, it says to identify the stimulus and the response. So take a second thinking about what it said in that paragraph above. What do you think the stimulus is? Well, what started this whole thing off? It started off because the blood pressure fell.

Right? That stimulus is a thing that moves out of the range of the normal physiological range, one under homeostasis. So my stimulus is going to be blood pressure falls. Alright. Now think what is the response?

Well, in a negative feedback loop, the response is going to push in the other direction, and sure enough, we're going to raise the blood pressure. So that response is going to be blood pressure rises. Okay. Let's look at the different components of the feedback loop over here. Remember, we have a receptor, a control center, sometimes called the integration center, and an effector.

So let's read each one and think how they match up. First up, we have the medulla processes low blood pressure signal and sends a message to the heart. Think what that sounds like. Well to me, it's processing low blood pressure and sending a message to the heart. That sounds like a control center.

We said the control center is often part of the nervous or endocrine systems, and it's going to integrate that response and tell the body what to do and how to respond. So the control center, I'm actually just going to draw a line to the medulla and the brain stem right there. The next one we have, it says after standing up quickly, baroreceptors above the heart, measure a drop in blood pressure. Alright. What do you think that sounds like?

Well, right there in the name baroreceptors. They are measuring a drop in blood pressure when it measures something. That is a receptor. And I'm just going to go ahead and draw a line to the heart. And then finally, we have the heart rate increases to increase blood pressure.

What does that sound like? That's going to be the effector. The effector is the thing that goes ahead and pushes back and changes the physiological condition to push it back to the original condition. So again, I'll draw an arrow back up to the heart for that one. Okay.

With that, we have some more practice problems below. I'll see you in the next video.