Digestive: Breaks down food
Respiratory: Breathe in oxygen and breathe out the carbon
Circulatory: circulates/regulates blood, transport ATP, O2, CO2, hormones, etc.
Excretory: Eliminating waste (poop and pee) which helps the body’s water balance.
Nervous system: Sends signals to your body, the commander. Without the brain, you won’t be able to think, move, or do any of the systems above.