How to Study the Slides
Updated 10/13/2022
In theory, your task is simple: Just learn the bullet points (and line diagrams and fill-in items). However, it's reasonable to ask for additional guidance. Do we really need to know everything in the bullet points? Are some bullet points more important than others? And how should we mentally organize this information? To provide guidance, I selected a slide completely at random* to use as an example of how to approach learning the material: 09Digestive 1, Slide 23.
This slide is about the structure of the esophagus. Let's look at each of the bullet points:
- "Has both smooth & skeletal muscle (all involuntary) - peristalsis" - As you learn this stuff, try to separate the information into things that are obvious or unsurprising, vs. things that are unusual or unique. In the slides about the structure of the GI tract wall, you know that peristalsis is performed by the muscularis externa, which consists of smooth muscle (at least that is our default understanding). But we learn here that the esophagus uses both smooth and skeletal muscle for this. So, be on the lookout for questions like "Which organ of the GI tract uses skeletal muscle in processing food?" Also, as I mentioned in presenting this slide, it's not surprising to find some skeletal muscle play a role in food processing near the beginning and end of the digestive tract, since the gut joins the body wall (which is largely skeletal muscle) at those points. Indeed, we will discuss skeletal muscle again when we get to the anus. The phrase "all involuntary" should be perfectly obvious information, since you know from first-hand experience that you cannot directly control your esophagus. Keep your eyes/ears open for ideas like these that add "logic" to the presentation. The more it makes sense, the better you'll remember it.
- "Cardiac sphincter at exit into stomach" - We will soon learn about the pyloric sphincter which is at the distal end of the stomach. Expect questions like "Give the correct sequence of structures, from proximal to distal". Notice that the terms cardiac, pyloric are already in alphabetical order.
- "Circular muscle layer of muscularis externa is thick" - This builds on your knowledge from the smooth muscle slides, where I did a sketch demonstrating what happens to the tube when circular muscle contracts. Think about questions you might see targeting this knowledge, such as: "Sphincters are structures that contract the [circular/longitudinal/oblique] layer of smooth muscle to [allow/prevent] food movement along the digestive tract".
- "Prevents reflux from stomach
-- If fails to close (e.g. due to hiatal hernia)
--> GERD (gastroesophageal reflux disease)" -- The main point here is that failure of the cardiac sphincter to close can lead to the disease known as GERD. Although I did explain in the presentation what "reflux" means (backward flow), the definition wasn't spelled out on the slides so I wouldn't have an exam question like: "Reflux means: A. Backward flow, B. Forward flow, C. Sideways flow...". However, I might have a question like "Reflux from [small intestine/esophagus/rectum/stomach] to [esophagus/pharynx/stomach/large intestine] causes [heartburn/diarrhea/etc.]" where your correct understanding of the word "reflux" aids you in selecting the correct answer. Or, I could simply restate the bullet point but add an error: "GERD results when the [circular/longitudinal] layer of smooth muscle fails to [open/close]". Also, you will sometimes see a question in which the options are the various diseases that were presented in that unit: "Which of the following is a disease of the joints? "A. GERD, B. Gout, C. Hiatal hernia...". So it's probably a good idea to make a list of all the diseases we've covered in this module, to help you keep them straight. Be on the lookout for terms that sound vaguely similar, like perhaps "GERD" and "gout". It may be worth making a list of terms and shuffling them randomly, so you can practice identifying what slide(s)/topics(s) there were taken from. For an acronym like GERD, I could theoretically write a question providing 5 different translations, e.g. "Gastric emptying response disease". As you can see, memorizing the bullet points perfectly is usually sufficient as long as you understand them, but taking the time to think about their connections to other subtopics will help prepare you for possible exam questions.
- There are several other topics that link to this slide. Just about all the details from the skeletal muscle powerpoint apply to the skeletal muscle that is found within the esophagus (e.g., it has sarcomeres, myofibrils, etc. etc.). (I suppose the only thing I'd leave out is that there are probably no origins or insertions in the skeletal muscle found here.) Likewise, the smooth muscle in the esophagus follows all the rules spelled out on the smooth muscle slides (e.g., it has gap junctions, etc.). So for example we could have a question like "Which of the following is found in the wall of the esophagus? A. Gap junctions, B. Myofibrils..." and the correct answer here would be one that includes both A and B. In terms of tissue layers, the wall of the esophagus will match the description presented in the introduction to the GI tract wall (e.g. it has muscularis mucosae, etc.), except here we've added specific exceptions that apply to the esophagus (i.e. that it also has skeletal muscle). In terms of the function of the esophagus -- of the steps in food processing that were presented earlier, clearly "propulsion" is what we are seeing here (and you already know from those slides that "peristalsis" is a major example of propulsion).
- What, if anything, can you ignore on this slide? The bullet points are pretty succinct, and there are no "side notes" in small font that you can disregard out of hand. But certainly, you shouldn't worry about some of the specific word choices -- I certainly won't have a question like: "In the cardiac sphincter, the circular smooth muscle of the muscularis externa is A. Thick, B. Very thick, C. Heavy, D. Voluminous". The concept here is simply that the circular layer is enhanced to perform this function. Also, in the chain of cause-and-effect, we can assume things are pretty black and white. In other words, I wouldn't have a question like "When the cardiac sphincter fails to close, what happens? A. GERD always results, B. GERD sometimes results, C. Reflux usually occurs..." However, I could have a question like "The cardiac sphincter is a thickening of what layer? A. Muscularis mucosae, B. Circular layer of muscularis externa, C. Longitudinal layer of... " As you process the information in these bullet points, look for "hard facts" (clear-cut, black & white distinctions) that can form the basis for writing an exam question that has an indisputable right answer and four indisputable wrong options.
- Students who have done well in this course have often reported that writing out the material on a whiteboard was a big part of their preparation for exams. Although I've been focused on a single slide, you'd want to practice with suitable "chunks" of information; since there are only 2.5 slides on the esophagus, it makes sense to write out everything from the slides about the esophagus in one list. I tried to imagine how a student might do this, as shown here. If you can add quick diagrams as shown in this example, the visual/spatial processing involved will help keep your brain interested, helps to supplement your "verbal" knowledge, and should help you retain the information longer. Note -- the example shown is probably too "pretty"; since you are doing this only for yourself, and the more practice the better, it should be as brief and simple as possible!
*We had 116 slides in Module 2 (Fall 2022). I used https://www.random.org/ to select a random number out of 116; the result was 89, which corresponds to the slide shown (Fall 2022).
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