Tuesday, September 05, 2006

Metabolism Seminar

Our seminar today was by Dr. Richard Hanson from the Case Biochemistry Department. He is a very enthusiastic presenter, and I thought he did a nice job of making connections between different metabolic systems. He pointed out to us several times that all metabolic pathways do not occur in every tissue of the body, and also that whether a particular pathway is on or off will depend on the dietary status of the individual.

For example, red blood cells perform glycolysis and the pentose phosphate pathway (they need NADPH to keep their glutathione reduced--glutathione is used to detoxify organic peroxides). But that's about all they do. They don't have any mitochondria, so they don't have a TCA cycle, electron transport chain, etc. In contrast, the liver has just about every possible metabolic pathway out there. The only thing the liver cells don't do is to use ketone bodies as a source of fuel, which makes sense because it's the liver's job to make ketone bodies for the rest of the tissues to use. As far as diet is concerned, if you've just eaten a meal, your anabolic pathways will be turned on, and your catabolic pathways will be turned off. But in the morning or any other time when you've been fasting, it's the other way around. The particular pathways also vary depending on what you eat. If you don't eat any carbs, guess what: your liver will make them via gluconeogenesis.

I noticed that Dr. Hanson wrote a chapter in our textbook about lipid metabolism. (We're using the Textbook of Biochemistry with Clinical Correlations by Devlin.) Several Case biochem professors have written sections of this book, actually. We've basically just started using it, but I can tell you now that it's a pretty dense book. I was reading the reviews for it on Amazon. The medical students almost all thought it was too detailed and dense for med school. The biochemists and professors thought it was great, particularly the section on metabolism, which is what we've been assigned to read. It does seem to be more like a grad school book to me too, but maybe they picked it for us because we're kind of a grad program here as well as a med program. And our problem sets are coming from there. So I am going to split the difference: I am doing the assigned readings out of Devlin for class, but I'm also going to read the Lippincott biochem book that a lot of my classmates are using. That book is supposed to have great illustrations and be good for board review anyway.

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