Answer:
Pancreas.
Explanation:
Pancreas is an organ that acts as both exocrine as well as endocrine gland. As exocrine gland, it secretes digestive enzymes into the small intestine that help in digestion of complex food molecules.
As an endocrine gland, it secretes glucagon (from alpha cells) and insulin (from beta cells) hormones, directly into the bloodstream. Both of these hormones are responsible for the regulation of blood sugar level in the body.
Thus, the correct answer is 'pancreas.'
It is used by every living cell.
Cellular respiration is a process of combining oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and discarding, as waste products, carbon dioxide and water.