Internal
Within The Body, Inside The Body
noun, の adjective
Something that's inside your body... hmm, could be a lot of things, but we can generalize and just say it's internal.
たいない
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
ちが、体内でどんなはたらきをしているのかしっていますか。
Do you know what function blood has within the body?
カボチャに多くふくまれるβカロテンは体内でビタミンAにかわります。
The kabocha squash is high in beta-carotene and it's converted into vitamin A in the body.
人間の体か吸血鬼の体かにかかわらず、血液は体内を循環する。
Blood circulates through the body regardless of whether it’s the body of a human or the body of a vampire.