As we know that the human is a multicellular organism. The cells are different to each other in their structure and functions. Each type of cells completes its own specialized work and forms only the group of similar types of tissues like- bones, cartilage, muscles, etc. in brief, a group of cells having similar structure and performs similar work is called tissue. Every tissues have their own specialized work. During the formation of tissues, the cells are interconnected with a unique type of substance, known as intercellular substance. Many tissues arrange together and from different types of body organs like- stomach, kidneys, liver, brain, etc. every organs have also their own specialized work. Different organs arrange together and form a system that performs a special task, for example- nose, larynx, trachea and lungs arrange together and form the respiratory system. This system acts as the exchange of oxygen and carbon dioxide between the body and atmosphere.
Human body main categories :