Translation of "Physiology" in Japanese

Human physiology is a three-credit course.

生理学は３単位です。

I'm often told that sleeping right after eating is bad for me, but then I think, isn't it built into our physiology that we get sleepy after eating?

食べてすぐ寝るのはいけないとよく言われるが、食べた後眠くなる生理と合わないじゃないかと思う。