You are right, the antibiotics one is pretty simple, I ran with it because I didn't want to get into personal details.
Let's put a simple one from my experience: No doctor has been able to tell me what the bilirubin is. They go on to tell possible causes, and what it means to have a high value and so on.. but after hours with them, no one could tell me what it is.
The closer I could get was for one of them to tell me that its secreted by the liver (close, but no cigar). The first paragraph in wikipedia explains it perfectly.
I know that my computer is powered by electricity. I know most of the ways to produce said electricity, but I've forgot the details of an hydroelectric plant even though I studied it in college; it's not part of my daily life.
I also know that power lines use alternate current and computers use direct current, but I've forgot the details of the AC/DC converter. Even though I was able to design one from scratch in university.
I also studied the internals of microprocessors up until the pentium, how they were designed and manufactured, but nowadays all I remember, vaguely, is the x86 assembler.
Do you remember every single detail you studied in college? Do you know how to calculate the root of a number by hand? I don't. Not anymore.