Cells, tissues and organs

In order of increasing complexity, multicellular organisms consist of:

organelles → cells → tissues → organs → organ systems

OrganelleCell structure that is specialised to carry out a particular function or job
CellBasic structural and functional unit of a living organism
TissueGroup of cells with similar structures, working together to perform a shared function
OrganStructure made up of a group of tissues, working together to perform specific functions
Organ systemGroup of organs with related functions, working together to perform body functions