pancreas, soap
胰 centers on the pancreas as an organ, and by extension, soap, which was historically made from pancreatic enzymes.
胰 combines the flesh component ⺼ with 夷, which likely contributes the sound. The character is used for the pancreas, and the soap meaning derives from the historical use of pancreatic enzymes in soap-making.
The flesh component ⺼ suggests a body part, and 夷 looks like a person with a bow. Imagine the pancreas as a fleshy organ that helps break down food, like a bowstring snapping to release cleansing enzymes—hence soap.
For イ, picture an easel (イーゼル) holding a painting of a pancreas: easel -> イ, and the pancreas is the subject.