Why is blood a cathartic (why does it cause vomiting)?
“Cathartic” is not entirely the right word – – it is more commonly used to mean promoting defecation (in other words a laxative). But you are right; blood does increase the tendency to vomit; it also is a “cathartic” stimulating expulsion of blood and stool through the intestinal tract. And your supposition is pretty much right on target. Blood is an irritant, both to the gastric mucosa and to other intestinal mucosa as well. And if the blood is xcoming FROM the stomach (or the esophagus or the junction of the esophagus to the stimach), the the vomiting can also be aggravated simply from the fact that the stomach gets “full”, in the worst of cases. In bleeding peptic ulder disease, the stomach is in an inflamed condition to start with. the blood makes it worse. I am not sure how much ios known about the cause of the iirritation. It may be connected to the erlease of serotonin and other very potent molecules from what are called “activated platelets”. Platelet activation occurs abdundtl
