The body has levels of organization that build on each other. Cells make up tissues; tissues make up organs; and organs make up organ systems. The function of an organ system depends on the integrated activity of its organs. For instance, the organs of the digestive system cooperate to process food. 

The nervous and endocrine systems direct the action and function of the body. The digestive, respiratory, and circulatory systems work together to remove waste from the body while also absorbing necessary nutrients and compounds. Your circulatory system carries vital nutrients to the skeletal and muscular systems.

They influence or control a wide range of physiological activities such as growth, development, puberty, regulating sugar levels, bone growth and appetite. 

Energy supply is the delivery of fuels or transformed fuels to point of consumption. It potentially encompasses the extraction, transmission, generation, distribution and storage of fuels. It is also sometimes called energy flow. 

Carbonhydrates, Proteins, Fats, Vitamins, Minerals, Water.

The system that contains the heart and the blood vessels and moves blood throughout the body. This system helps tissues get enough oxygen and nutrients, and it helps them get rid of waste products. The circulatory system carries oxygen, nutrients, and hormones to cells, and removes waste products, like carbon dioxide. These roadways travel in one direction only, to keep things going where they should.

The endocrine and nervous systems communicate with each other through the hypothalamus, which controls basic drives such as hunger and thirst. The hypothalamus also regulates the pituitary gland, which governs the release of hormones by the body's other glands. 

A reflex is an involuntary and nearly instantaneous movement in response to a stimulus. The reflex is an automatic response to a stimulus that does not receive or need conscious thought as it occurs through a reflex arc. Reflex arcs act on an impulse before that impulse reaches the brain.