Friday, December 08, 2006

Renal Clearance Seminar, PBL, and POD

We started out with a seminar this morning about how the kidneys are able to filter waste products out of the blood to be excreted. It's a pretty complex process. One important thing we learned is that the kidneys filter substances out of the blood based upon both size and charge. If the molecules are large like proteins, they won't get filtered. If they're very small like amino acids or glucose, they will get filtered. And if they're in the middle, they will get filtered more if they're positively charged and less if they're negatively charged. That is because the walls of the glomeruli (kidney capillaries) are negatively charged, so they repel negatively charged substances in the blood. Fortuitously, most of our blood proteins have negative charges on them. We also learned how to calculate the rate at which the kidneys are filtering the blood. This can be done by measuring the concentration of certain naturally occurring substances in the urine or by giving the patient certain drugs and measuring how fast they get filtered and show up in the urine. All good stuff.

In PBL, we finished our case today and kind of half-heartedly did a concept map. Most of us are not too gung-ho about doing concept maps, but our tutor did not seem very happy about the fact that we kind of blew it off. I hope that this is not going to make problems for us later. The presentations were good for the most part, and we had no problem finishing on time.

Our POD speaker was my group's seminar leader from Tuesday. His talk was good, although I think he could have been more interactive than he was. But he didn't go over time, and the work he is doing is very relevant to what we're studying since he's a nephrologist. One thing he is working on is preventing kidney disease in patients with diabetes. I hadn't realized before today that renal failure can be a complication of diabetes. Not all diabetics end up having a problem with their kidneys, but a significant minority of them do. Basically what happens is that those same negative charges in the glomeruli that I mentioned earlier wind up being lost, along with some other abnormalities like holes in the capillary walls. Those are both bad things, because together they allow proteins that should be retained in the blood to get filtered by the kidneys. These proteins can be detected in the urine, leading to a condition called proteinuria. This same guy is giving a talk in a couple of weeks for the internal medicine grand rounds, and I think that I'm going to go.

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