text: <unk>  refers to the movement of blood through the network of blood vessels supplying the brain. The arteries deliver oxygenated blood, glucose and other nutrients to the brain and the veins carry deoxygenated blood back to the heart, removing carbon dioxide, lactic acid, and other metabolic products. Since the brain is very vulnerable to compromises in its blood supply, the<unk>  circulatory system has many safeguards. Failure of these safeguards results in cerebrovascular accidents, commonly known as strokes. The amount of blood that the<unk>  carries is known as<unk>  blood flow.
  The following description is based on idealized human<unk> . The pattern of circulation and its nomenclature vary between organisms.
option_0: Cerebral circulation
option_1: Coronary circulation
option_2: Cardiac cycle
option_3: Circulatory system
option_4: Systemic circulation
option_5: Hemodynamics
option_6: Autonomic nervous system
option_7: Intracranial pressure