 Hey, everybody, Lance Goyki here. Just a quick one today about one little thing that we might say about the heart. So the heart can, it expands, it stretches like any other muscle because heart muscle is muscle. It stretches like any muscle and then it contracts like any other muscle. So it's just like your bicep doing a bicep curl. It stretches on the way down and it contracts on the way up. It gets shorter on the way up. Now for a heart beat, the blood comes in through the vena cava into the heart. As all that blood runs into the heart, it kind of acts like a balloon filling up and it stretches out like this and then that stretch then is is met with a contraction, a like a reflexive contraction that then ejects the blood into the next chamber or depending on what chamber you're in out to the next or out to the rest of the body for the cardiovascular circulation. We call the amount of blood that is ejected the stroke volume. So if my heart rate is increasing because my energy demands are increasing, I'm putting more blood into the heart and I get a bigger stretch and then I therefore get a bigger contraction and I move more blood from each contraction. And so what we say is this is our stroke volume. Each stroke of the heart has a volume of blood that it moves. So as my heart rate starts to go up or as my energy demands start to go up, I start to push more blood in on each given stroke.