Exam 3 scores are posted! And a HUGE thank you :)

Exam 3 scores are now posted on Moodle. I can’t turn in grades until the evaluations are in, but at least you can see what you got on your exam. You did great, as usual. The mean was 59/66 (89.4%), the high was 66/66, and the low was 49/66…so everyone passed! Yay!

If you ever want to come and take a look at any of your exams, just let me know, and we can find a time that fits into your schedule.

Finally, I want to thank you for your incredible kindness and support this semester. You showed such genuine compassion and care – it brings tears to my eyes. The card you gave me is right here on my desk and I read all your kind comments regularly. Thank you for all the kind emails, for your smiles and energy during class, and for your concern and prayers. It was a joy to come to “work” (not work) and be with all of you. I miss you already, but I look forward to seeing you next year in pathology!

 

 

Exam 3 points breakdown (remember endocrine is included!)

Just wanted to let you know the number of questions on each topic, so you can use your study time accordingly. Remember that we didn’t cover endocrine on the last exam, just to make it a little easier since you had a couple big exams right in a row that week. So it will be covered on this exam.

Here’s the breakdown:

  • Endocrine – 10 questions
  • GI – 15
  • Pancreas/liver/gallbladder – 7
  • Respiratory – 10
  • Renal – 10
  • Female reproductive – 7
  • Male reproductive – 7

Question about muscularis layers in GI tract

Q. I am slightly confused about muscularis externa. Is muscularis externa only present in places where muscularis mucosa is not? For example, the oral cavity, upper esophagus, and anal canal. Is it possible for them both to be present? And muscularis is not always present as a layer in the GI tract, correct? When present does it typically present in the same layer that the muscularis mucosa would be?

A. Those are great questions! As you noted, there are two “muscularis” layers in the GI tract: the muscularis mucosa and the muscularis externa.

  • The muscularis mucosa is a thin little layer of smooth muscle that is part of the mucosa (which includes epithelium, lamina propria, and muscularis mucosa). It innervates the inner layers of the mucosa, and it also shows you nicely where the mucosa ends, and the submucosa begins.
  • The muscularis externa is a thick layer of muscle that provides the main structural support all along the GI tract. It sits between the submucosa and the serosa/adventitia.

Basically the GI tract is just a tube with four concentric layers, like this:

From inside to outside, there’s mucosa (epithelium, lamina propria, and muscularis mucosa), submucosa, muscularis externa, and serosa/adventitia.

All levels of the GI tract have this exact structure, except for:

  • the mouth (which I’m not allowed to discuss with you lol)
  • the anus (which is only slightly different…its mucosa is comprised of just epithelium, with no lamina propria or muscularis mucosa).

I think that pretty much covers it.  Having said all that, here are my direct answers (in blue)!

I am slightly confused about muscularis externa. Is muscularis externa only present in places where muscularis mucosa is not? For example, the oral cavity, upper esophagus, and anal canal. No. Both the muscularis mucosa and muscularis externa are present at every level of the GI tract except for mouth and anus (as mentioned above). The upper esophagus btw is not an exception – it has the same four-layered structure you see everywhere else. Is it possible for them both to be present? Yep! And muscularis is not always present as a layer in the GI tract, correct? No – both types of muscularis layers are pretty much always present. When present does it typically present in the same layer that the muscularis mucosa would be? No – the muscularis mucosa is always part of the mucosa (the innermost of the four layers), and the muscularis externa is always located between the submucosa and serosa/adventitia. 

Pits/glands vs. villi/glands

Here’s something that bugged me when I was learning about the histology of the GI tract. It seems like the stomach and the small intestine have kind of the same thing going on. I mean, if you look at the histology images and the drawings, they both have glands at the bottom and other structures (covered with plain columnar epithelium) above. In the stomach, the things on the top are pits, and in the small intestine, the things on the top are villi. It seemed hard to visualize exactly how they looked different.

I decided to make a short video explaining the difference. I think it’s easier to understand if you can see someone drawing on the pictures. So here it is – I hope if some of you had the same problem that this will solve it!

A funny thing happened in pathology…

So here’s the funny thing that happened in pathology lecture yesterday.

There’s a fairly long preamble, in which you can hear snickering and giggling, which is funny enough in itself. Make sure to turn up the volume so you can hear the student who finally tells me what’s so funny (at 2:20) and then – this is the best – quietly says “…ohhhh” (at 2:24) while it dawns on me.