Level of organisation

• There are about 12 different organ systems
• [smaller > bigger]

  Organelles > cells > tissue > organs > organ system > organism
• • Organelles: parts that make up a cell like the nucleus, ribosomes, and mitochondria, each with a specific role
• • Cells: come in various shapes and sizes, containing different combinations and numbers of organelles; specialized cells include epithelial cells, muscle cells, and glandular cells
• • Tissues: groups of similar cells working together to carry out a specific function, like epithelial tissue, muscle tissue, and glandular tissue
• • Organs: groups of different tissues working together to perform a particular function, e.g., the stomach
• • Organ systems: groups of organs working together to perform a specific function, like the digestive system or cardiovascular system
• • Organism: the highest level, with multiple organ systems working together