Illustration of the mechanisms of cerebral autoregulation. (A) In the myogenic mechanism, changes in the transmural pressure influence changes in arterial diameter through contraction or relaxation of the smooth muscle. (B) In the metabolic mechanism, the concentration of carbon dioxide (CO₂) produced in the oxidative phosphorylation process affects small artery diameter. (C) The endothelial mechanism is based on the paracrine secretion of substances (nitric oxide and vasoconstrictors like endothelin-1 and thromboxane A2) that stimulate the smooth muscle. (D) In the neurogenic mechanism, neuroglial cells contribute to the control of moderate- and small-diameter vessels by secreting different neurotransmitters with vasoactive properties.