The human body is made up of different levels of organization from cells to tissues to organs to organ systems. Cells form tissues like epithelial, nervous, muscle, and connective tissues. Tissues working together form organs which carry out specialized functions. Organs that work together are organized into 11 major organ systems that maintain homeostasis by working cooperatively to keep the internal environment stable. The 11 organ systems are muscular, skeletal, digestive, respiratory, nervous, integumentary, endocrine, lymphatic, reproductive, circulatory, and urinary.

1. Human Body Levels of Organization

3. List 11 major organ systems.

6. Epithelial Covers and protects underlying tissues. Examples – skin, inside of mouth/nose

7. Nervous Sends electrical signals throughout the body Examples – Nerves, Brain, Spinal cord

8. Muscular Made of cells that contract and relax to produce movement Examples – Biceps, quadriceps, tongue

9. Connective Joins, supports, protects, insulates, nourishes and cushions organs and joints.

10. Tissues to Organs Tissues Form Organs Two or more tissues working together to carry out a specialized function form an organ.

12. Organ systems work together to maintain homeostasis.