What is the third stage of cellular respiration

the third and last stage of cellular respiration would be called electron transport. It takes place on the inner membrane of the mitochondrion. Electrons are transported from molecule to molecule down an electron-transport chain

these muscles maintain the blood pressure in the vessels. the smooth muscles are innervated by nerves of the autonomic nervous system. when the muscles contract, they cause vasoconstriction of the vessels and increase blood pressure. when the muscles relax, they enable vasodilation of the   blood vessels hence reduce blood pressure.