Each cell is made up of many organelles that cooperate to enable the cell to carry out its function.
Tissues are collections of cells, although this classification is arbitrary and may not be relevant in terms of function.
Organs are made up of collections of tissues that cooperate to carry out specific tasks on behalf of a bigger system.
These systems then interact with one another for the benefit of the organism as a whole.
Your body is a component of the greater human society.
Some of the major systems in your body include:
- Circulatory/Respiratory
- Digestive
- Muscular/Skeletal
- Nervous
- Endocrine
- Immune
Consider the muscles, chambers, and valves of your heart. The complete heart assists in the movement of blood via your lungs, veins, and arteries, supplying the rest of your body with oxygen and nutrition as well as acting as a conduit for hormones and immune system components to travel throughout your entire body.