How does the human heart this level of organisms relate cells? To the organ system?

Cells makeup tissues, and tissues make up organs, and organs make up organ systems. A tissue is group of cells which work together to perform a specific function e. g. muscle tissue and lining of the intestine. An organ is a group of different tissues which work together to do a particular job e. eg the heart which is made of muscle tissue and nervous tissues working together. An organ system is a group of organs working together to do a particular job, e. g. the circulatory system which includes the heart, and lungs.