Other elements and compounds also exist in cycles. Elements pass along food chains when animals eat plants and other animals. Many humans eat protein in the form of meat from other animals. The body breaks this down into amino acids and then uses these to make proteins within the body for growth and repair. When someone dies these building blocks are returned to the environment to be used by other living organisms.
Decomposing bacteria and fungi break down dead organisms. They help recycle minerals and nutrients to the environment, which can then be used by other organisms. As they decompose dead matter, the decomposers also respire and so release carbon dioxide to the environment, contributing to the carbon cycle.