How is acne vulgaris connected to the system?

ALL bodily systems are connected in some way to the circulatory system. The circulatory system is often used to simply transport a bunch of "stuff" throughout the body. Most notably the Endocrine...

Respiratory system

a circulatory system is the system that controls the circulation of blood through the body.

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The lymphatic system is not directly connected to the digestive system. The lymphatic system has to do with draining excess fluids in the extracellular space.