PSL300H1 Lecture Notes - Lecture 6: Extracellular Fluid, Depolarization, Central Canal
Document Summary
3 distinct barriers: blood (interstitial fluid, cerebrospinal fluid (ventricles, csf-interstitial fluid. **free diffusion between csf and csf interstitial fluid. [na+] of blood = [na+] of interstitial fluid. [k+] of blood > [k+] of interstitial fluid (since too much k could lead to depolarization block) Subarachnoid space - filled with csf to make a suspension cushion (i. e. brain floats), otherwise brain would impact with skull. Pia mater - tethered to arachnoid by arachnoid "trabeculae" There are filaments teetering the arachnoid to pia mater. Does a lot of metabolic work, e. g. mopping up neurotransmitter. Taking glucose from blood, and through glycolysis gives neurons lactate as energy. Opposite to nutrient flow in astrocytes, a metabolic signal moves outward to blood vessels, signalling neuronal activity level. Glutamate in synapses triggers ca2+ release within astrocytes; ca2+ wave travels through astrocytes and triggers prostaglandin (pge2) release at end-foot. Glutamate --> ca2+ release in astrocytes --> pge2 release at the foot of astrocytes --> vasodilation.
