1. _______ is a tubular structure through which urine is excreted out of the body.   Hint First letter clue   2. Blood is returned to the heart from various body parts through blood vessels known as _______.   First letter clue   3. _______ is also known as 'voice box'.   First letter clue   4. Food descends from the mouth to the stomach through a muscular tube known as _______.   First letter clue   5. Kidneys are the main _______ organs.   First letter clue   6. An average human adult has _______ teeth.   First letter clue   7. A healthy human adult has _______ bones.   First letter clue   Skip to Diagrammatic repr... ⇒