9. (b ) Myelinated axons are called nerves in the PNS. Nerves can be myelinated and unmyelinated axons present in PNS. This myelin forms insulation and helps in proper functioning of the nervous tissue. 10. (a) MAO breaks down Norepinephrine intracelluraly in the presynaptic nerve terminal. It is located inside the mitochondria. COMT breaks NE extracellularly. NE is broken down by these two enzymes. Solution 9. (b ) Myelinated axons are called nerves in the PNS. Nerves can be myelinated and unmyelinated axons present in PNS. This myelin forms insulation and helps in proper functioning of the nervous tissue. 10. (a) MAO breaks down Norepinephrine intracelluraly in the presynaptic nerve terminal. It is located inside the mitochondria. COMT breaks NE extracellularly. NE is broken down by these two enzymes..