What are the physical and chemical changes or reactions that occur within the body collectively known as?

Metabolism is a collective term for the physical and chemical changes or reactions that occur within the body.
Physiology the branch of biology that deals with the normal functions of parts living organisms.

Assimilation in biology means the absorption and digestion of food or nutrients by the body or any biological system.

Excretion is the process of removing waste and toxins from the body.

Excretion. the removal of metabolic wast subtances as a result of the chemical and physical activities the body undergoes.

Physical and chemical changes or reaction that occur within the body is called metabolism

Please make question more detailed, it's a bit vague in myopinion.