• 粘膜ねんまく — mucous membrane
• 鼓膜こまく — eardrum; tympanic membrane
• 網膜もうまく — retina (eye membrane)
• 膜まく — membrane; film; thin layer
• 薄膜はくまく — thin film; delicate coating
• 保護膜ほごまく — protective film or layer

The kanji 膜 uses the body radical 月 (にくづき) on the left, telling us it has to do with the body or flesh. On the right is a phonetic part related to “wrap” or “cover”. Together they point to a thin layer that covers and protects — a membrane over organs, the eye, or the eardrum.