1. Structure & Cellular Biology

• Organization: The CNS consists of the brain, spinal cord, and CN I-II. The PNS contains CN III-XII, spinal nerves, and the ANS.
• Cells & Myelin: Neurons conduct action potentials via saltatory conduction across nodes of Ranvier, accelerated by myelin. Astrocytes form the blood-brain barrier and create scar tissue (gliosis) upon injury. Oligodendrocytes myelinate CNS axons; Schwann cells myelinate PNS axons.
• Synapses: Neurotransmitters cross synapses to alter impulse transmission, using excitatory (glutamate) or inhibitory (GABA) pathways.

2. Pathways, Lobes & Perfusion

• Tracts: Ascending tracts carry sensory input (spinothalamic for pain/temp; dorsal colum ...