 Hey, team, today we're starting our conversation about kidneys. We're going to spend two entire lectures talking about kidney function. I feel like if I had to pick a favorite body system, kidneys might... Okay, they're in organ. Kidneys might be my favorite organ in the body. The mechanism by which kidneys do their job, their job, the... It's just really, really, really cool. When you think of kidneys, if we were going to make a list of kidney functions, I'm sure that when you think of kidneys, the first thing you think of is urine production. And it's true. That's important. Why are we producing urine in your kidneys? It actually has to do with cleaning the blood. Urine production is a byproduct of blood cleaning. But kidneys, that's really important. You don't want your organs to be swimming in urine. So let's get rid of that. Awesome. Very important job for the kidneys. But kidneys also play a critical role in maintaining the homeostasis of the extracellular fluid. When you think about blood, blood is extracellular fluid. So kidneys help maintain blood pressure. They help maintain pH homeostasis. And even other ion concentrations. They play a role in making sure that all of that is staying within homeostatic range. We're going to spend this entire first lecture talking about essentially the function of the place where kidney structure meets cardiovascular structure, where the blood comes in contact with the nephron, which is the functional unit of the kidney. We're going to get stuff out of the blood. We're going to filter the blood. And that's the process we're going to primarily talk about today. In the next lecture, we're going to talk about basically how we unfilter or reabsorb all the stuff that we filtered out in this lecture. And then we spend an entire lecture talking about this part. How does the kidney help maintain homeostasis in all these different capacities? So really, we're spending three lectures talking about nephrons and kidneys, which hopefully should indicate to you where I place it on the importance scale. All right, let's talk kidneys.