INTRACRANIAL SURGICAL PHYSIOLOGY Glucose: 60 mg/min which is 25% of total body consumption Oxygen: 45ml/min which is 20 %o of total body consumption Oxygen uptake depends upon: 1: cerebral blood flow 2: oxygen content of blood 3:pH 4:body temperature OXYGEN+ 1mole GLUCOSE 38 MOLES OF ATP In hypoxia 1 mole of glucose gives 2 molecules of ATP plus Lactic acid.

ENERGY(ATP) 1:Ionic gradient across the membrane 2:neurotransmission/neurotransmitters Synthesis,release,uptake and destruction of neurotransmitters. 3:preservation of cellular structure in nervous system which includes complex process of lipid metabolism which includes process of myelinization of neurons. 4:synthesis of proteins for information storage 5:CSF formation process Total brain ischemia leads to loss of consciousness in 15 seconds Irreversible damage in 2 minutes.

Energy Crisis of the Brain 1: Hypoxia/ischemia 2: Hypoglycemia Effect is in the form of change in EEG depletion of tyrosine hydroxylase required for synthesis of noradrenaline/dopamine Fall in acetylcholine Decrease in brain Lipids such as phospatidylinositol Efflux of potassium and influx of calcium CLINICAL EFFECT OF INTERRUPTION LEADS\ TO ALTERATION IN PERSONALITY,JUDGMENT, MEMORY,IMPAIRED TOLERANCE OF DRUGS AND ALCOHOL AND PROFOUND COMA

CELL DAMAGE DUE TO ENERGY CRISIS 1:Purkinje cell in cerebellum 2:3-5-6 layer in cerbrum 3:somersector of Ammons horn in hippocampus 4:boundary zones Venous(jugular) Po2 30 unconsciousness 15 EEG 10 cell death

ml\mn 150 normal vol

Hypercapnia Hypoxia