This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': 'Cerebral Ischemia occurs when cerebral blood flow is less than: \nSelect and explain. \nA. 10 m1/100g / minute, B. 20 m1/100g / minute, C. 40 ml/ 100g/minute, D. 50 m1/100g/minute', 'role': 'user'}, {'content': "Answer: B \nExplanation: Answer is B (20 m1/100g / minute): Cerebral blood flow < 20 ml / 100g tissue per minute causes cerebral ischemia without infarction (Harrison 's 18 th /3271) Critical Cerebral Blood Flow Effects * 5 20 mU100 gm/minute * Cerebral Ischemia without infarction (Reversible unless prolongedfOr several hours or days) * Clinical syndrome of TIA * Consciousness is usually lost as the brain tissue loses the capacity to make neurotransmitter substances and coma ensues * Damage is Reversible * 16-18 ml / 100 gm / minute * Cerebral Infarction within one hour * 10 ml / 100 gm / minute * Cerebral Infarction within several minutes * Membrane integrity is lost * Biochemical cascade of neuronal destruction becomes irreversible * Zero ml / 100 gm / minute * Death of Brain tissue within 4 - 6 minutes", 'role': 'assistant'}]