1. _______ are the organs of hearing.   Hint First letter clue   2. Blood is distributed to various parts of the body through blood vessels known as _______.   First letter clue   3. Heart is divided into _______ chambers.   First letter clue   4. Blood is returned to the heart from various body parts through blood vessels known as _______.   First letter clue   5. _______ are the main respiratory organs.   First letter clue   6. Heart lies on the left side of the _______ cavity.   First letter clue   7. Complex food particles are broken into simple food particles through the process of _______.   First letter clue