Circulatory -
Brings oxygen and nutrients where it is needed, removes toxic chemicals, maintains a stable body temperature
Digestive -
Food and nutrients are absorbed in the small intestine. These nutrients are necessary for other body systems to maintain homeostasis.
Excretory -
Removes all waste from the body, kidneys filter chemicals, liver filters toxins
Enhancers are eukaryotic DNA sequences that can be used to elevate transcription and have variable positions and orientations.