Fill in the blank with the appropriate term. 1. The human machine is organized at different levels, starting with the cell and ending with the entire . 2. At each higher level of organization, there is a greater degree of . 3. Many human cells are specialized in form and . 4. Muscle cells have many that provide the energy they need to move the body. 5. After the cell, the is the next level of organization in the human body. 6. tissue protects the body and its internal organs. 7. Epithelial tissue secretes substances such as . 8. Nervous tissue makes up the brain and the that connect the brain to all parts of the body. 9. Human organs are organized into organ . 10. The system takes in oxygen and releases waste gases. 11. The skeletal system provides to the body and protects internal organs. 12. Functioning together, the organ systems keep , pH, and other conditions at just the right levels to support life processes.