Guillermo was finding it difficult to walk up the steps to his family’s apartment. His doctor thinks that his cells might not be getting enough oxygen or glucose. Why does having low levels of glucose or oxygen in his cells make it difficult for Guillermo to walk up steps? Which body systems should the doctor test in order to find out whether Guillermo’s cells are getting enough oxygen and glucose and why?

PLEASE BE A LESS ADULT AWNSER PLEASE