1. _______ are the organs of hearing.   Hint First letter clue   2. Heart lies on the left side of the _______ cavity.   First letter clue   3. _______ is a tubular structure through which urine is excreted out of the body.   First letter clue   4. Food descends from the mouth to the stomach through a muscular tube known as _______.   First letter clue   5. _______ are the main respiratory organs.   First letter clue   6. Oral cavity remains moist due to presence of a fluid known as _______.   First letter clue   7. Kidneys are the main _______ organs.   First letter clue