G I R e v i e wThis lecture replaced the integration lecture.

Slide 1 - Gastrointestinal Physiology: reviewDr. Evgeny Pavlov - So this is pretty much a brief summary of GI. I told you to look at this part. Sometime today. So it’s not like a real review, but what happened, an issue on the last quiz, was that yeah, I need to spell out all the things that should be on the quiz, rather than you relying on the textbook for the proper section of the textbook. So pretty much what I remember, I hope I said “everything will be on the quiz,” so I just summarized which are on the quiz in detail.

Slide 2 - GI Hormones – summaryDr. Evgeny Pavlov - The purpose is to encourage you to really read the textbook parts on each specific subject, so you understand it more, like each part is short. I’ll post this when I get back to my office.

So there are just a couple of things which I think will be important, so first these are the summary slides are for hormones and same for paracrines and endocrines. So we will talk about it longer, they come up in lecture, so I think it’s important to know pretty much most of this stuff, and I think we covered this, in more or less detail.

But there will definitely be questions about what this does or what that does, so some will be direct and some will be like “thru some kind of signaling, if you do this then what will happen then.” So this is one thing I didn’t mention the second name for the gastric inhibitory peptide, so we talked in terms of the connection to GI function, but the important thing is its name is spelled out as (G)lucose-dependent (I)nsulinotropic (P)eptide. So it is also spelled out GIP, and what it does, and it might come up; it stimulates glucose-dependent release of insulin. In pancreas we have these islets which contain insulin, this is one of the roles of gastric inhibiting peptide, which again is listed here in the table, so I hope you will learn that, but it’s kind of something to point out. We didn’t talk about it in GI block because, strictly speaking, it’s not related to GI system as it is metabolism, but it might be there.

Slide 3 - Terms describing GI motilityDr. Evgeny Pavlov - Also I didn’t spell out terms for motility, I’m not really, I think it’s more not memorizing them but still there may be questions on them, so please memorize at least this part haha (points to whole list). They are fairly [sic] simple, and integral, so I figure if we talked motility you’d just look them up, but apparently for inspiration part, I’ll just spell them out. So there are like five terms which are here, which summarize, we talked about some of these in terms of movement, but how many I actually named is in the textbook. Retropulsion is something that is responsible for mixing content of stomach so when food pushed forward it kind of gets moved back. Then segmentation is kind of movement of the GI tract where it’s contraction but not really propulsion. So contracts and then relaxes then helps to mix food.

Transcribed by Janki Gajera! April 14, 2014

And then migrating motility complex, which is simply contraction during fasting. No food in the GI system, there are still some leftovers, food gets moved towards the end of the GI system. This process governs specific contraction, which collectively called migratory motility complex. Then peristalsis, which we talked about, which is coordinated contraction which propels food thru GI system, it’s very prominent in the esophagus for example, but the principle of motion like peristalsis has nothing to do with GI but is the principle, right? And then receptive relaxation, this is when like food enters in the stomach, it spreads out to accommodate the food coming from the esophagus and this storage movement and combine this movement, called receptive relaxation.

Slide 4 - Pancreatic secretion regulation (intestinal phase)Dr. Evgeny Pavlov - So in terms of signaling, for example, some of this will be review of different hormones present inside the liver. It’s much easier to memorize and review them if you look at the signaling pathways. A few slides like that, we went thru them in detail. Please do that. Please look at them carefully. Listen to lecture. Please look at the book. Make sure you understand all of this stuff like fat would release CCK from the I cells and how they would stimulate pancreatic secretion and how this process causes the combined action to increase release of different secretions and look at those things I mentioned, the few things.

Slide 5 - Enterogastric reflex – inhibitory reflexDr. Evgeny Pavlov - Another term which we never really talked about, the names of the neuronal reflexes but there might be, this one mentioned either an increase in the, in the exam, which is enterogastric reflex. It’s not a major question but still you might come across this. I’m sure that they were outlined in lecture. Just to review this, the inhibitory reflex, which is neuronal reflex, when you have some signaling coming from stomach processed by the brain, sending the result back. So it’s sensitive to the pH change in the stomach and sensitive to chyme, the mixing of gastric acid and food. That’s what triggers this reflex. This results in inhibition of gastric motility and inhibition of stomach emptying and secretion of gastric acid. Overall what it does is signal there is enough stuff in duodenum and prevents emptying of food from the stomach.

Yeah, I hope this is it and I hope I didn’t forget something. This is it, email me if you have questions or if you have now questions, you’re welcome. We’re good?

...... class claps ….. “thanks”

Transcribed by Janki Gajera! April 14, 2014