This view of a gastric gland marks the first post in this blog about biological cartoons. The goal of the blog is to share some of the cartoons I’ve been using in my classes, and meet up with like-minded folks who share my view — that most lectures and nonfiction books are better off with a few cartoons. I will also broaden the discussion at times to look at the whole genre of educational cartooning, and share with you some of the best examples I’ve found.
But my training is in biology, so that will be my main focus. The choice of the gastric gland is perfect, not just because I will be lecturing on it tomorrow (really!), but it also represents the anxiety (and a little extra stomach acid) I have in launching this project. I have never done a blog before; it sounded like too much time commitment. But as the cartooning has become central among my interests, I realized it was time to move beyond the powerpoint slides and reach out — I’m hoping at the very least, there are a handful of teachers out there who might find a place for these cartoons in their classroom.
Since space is not an issue here, what I will do is show the cartoons unlabeled, and provide explanatory text, with the main terms in bold. The drawing shows the main cells of the stomach epithelium (orange) secreting mucus, which protects the epithelium from its own secretions. Nevertheless, there’s rapid turnover of cells (replaced every few days), and a couple hapless oldsters are shown plunging into the roiling cauldron of stomach acid and food, known as chyme. This fortunate term (which, happily, comes from the same Indo-European root as “humor”!) gives rise to a plethora of puns, one of which is posted on the “wall” next to the “police chief” cells representing chief cells. These cells secrete pepsinogen, an enzyme precursor, which when activated (by acid) digests proteins in the stomach. So the police chief is truly “taking a bite out of chyme”, which is a reference to the “take a bite out of crime” ad campaign from the 80’s.
Stomach acid is secreted by parietal cells (blue), which are the most realistic drawings in the figure — their “teeth” are the many microvilli (convolutions of the membrane) that add surface area, maximizing the ability to secrete acid. At the bottom of the gland is an enteroendocrine cell (purple), a general term for the many epithelial cells of your gut that secrete hormones. The cell is “tasting” the food molecules in the gland, and sending out a hormone into the bloodstream to activate other glands of the stomach. Finally, the pink cells with pacifiers are (you guessed it) baby cells, or stem cells, which have a sort of “immortality”, continuing to divide throughout your life, while their progeny migrate up and down to become the replacement cells in the epithelium.