Neuron Specializations: 10 Unique Properties of Nerve Cells

Neurons are structurally and functionally distinct from other cells, enabling rapid information processing.

1. Excitability

Generate action potentials (APs) in response to threshold stimuli.

2. Polarized Resting Membrane

~ -70 mV maintained by Na⁺/K⁺-ATPase and leak channels (K⁺ > Na⁺ permeability).

3. Action Potential (All-or-None)

Rapid depolarization (Na⁺ influx) → repolarization (K⁺ efflux) → hyperpolarization. Self-propagating.

4. Refractory Periods

• Absolute: No AP possible (Na⁺ channels inactivated).
• Relative: Stronger stimulus needed (K⁺ channels open).

5. Synaptic Communication

• Chemical: Vesicular neurotransmitter release → receptor binding → postsynaptic potential.
• Electrical: Gap junctions (connexons) → direct ion flow (fast, bidirectional).

6. Integration

Spatial and temporal summation of EPSPs/IPSPs at axon initial segment → decision to fire.

7. Polarized Morphology

• Dendrites: receive inputs (high surface area, spines).
• Axon: single output; can be >1 m long; myelinated for speed.

8. Myelination

Oligodendrocytes (CNS) / Schwann cells (PNS) → saltatory conduction at nodes of Ranvier (up to 120 m/s).

9. Structural Plasticity

Spine turnover, axonal sprouting, synaptic pruning — basis of learning/memory.

10. Adult Neurogenesis

Subventricular zone → olfactory bulb; hippocampal dentate gyrus → pattern separation, mood regulation.

These features create the computational power of nervous systems.