1. Complex food particles are broken into simple food particles through the process of _______.   Hint First letter clue   2. Food descends from the mouth to the stomach through a muscular tube known as _______.   First letter clue   3. Blood is returned to the heart from various body parts through blood vessels known as _______.   First letter clue   4. Bronchi are _______ in number.   First letter clue   5. _______ is the organ of smell.   First letter clue   6. _______ is a sac-like structure which stores urine.   First letter clue   7. _______ is also known as 'voice box'.   First letter clue