Stagnant or Ischemic Hypoxia is an inability to provide required oxygen because the heart doesn’t pump as efficiently due to multiple reasons, causing cell damage.
Myogenic theory is the theory that smooth muscle requires oxygen to stay contracted, thus oxygen concentration regulates the contraction of precapillary sphincters.
Metabolic theory is the theory that the increase in metabolic rate or decrease in nutrient/oxygen availability cause an increase in the release of vasodilator substances like lactic acid that create systemic vasodilation.