I’ve done a poster with some basic organs of the body for young children. The kidneys are on another page as they are located behind the liver and stomach etc. I was also unable to show the oesophagus (食道 sik6 dou6) connecting to the stomach as it’s located behind the trachea and heart, but in front of the spine, which would probably be confusing for children. I’m thinking about doing a less cutesy and more anatomically accurate poster with more organs listed, if this would be helpful!
In general, you can just say 心 sam1 (heart), 肝 gon1 (liver), 膽 daam2 (gallbladder), and 腎 san6 (kidneys) and this is accurate. You can also add 臟 zong6 for the more formal terms. 膽 daam2 can also be used as an abbreviation for 膽量 daam2 loeng4 i.e. courage, which you’ve probably heard in films, so it depends on the context in which it is used. For example, 大膽 (daai6 daam2) = courageous, 細膽 (sai3 daam2) = cowardly, 無膽匪類 (mou4 daam2 fei2 leoi6) = coward). You’ve probably heard the last phrase in movies before!
Edit: I’ve changed 腸 (coeng2) intestines to the second tone, as I had it down incorrectly as the fourth tone before.
甲狀腺 gaap3 zong6 sin3
膀胱 pong4 gwong1