C2.2 Neural Signaling 1 Summary Notes

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C2.2 Neural Signaling – Summary Notes C2.2.1: Neurons as Cells Carrying Electrical Impulses Neurons are specialized cells with dendrites, axons, and cell bodies. Impulse = electrical signal caused by movement of ions across the membrane. Axons transmit signals; dendrites receive signals. Direction: dendrite → cell body → axon → synaptic terminal. C2.2.2: Generation of Resting Potential Resting potential: ~–70 mV Maintained by: Na⁺/K⁺ pump: 3 Na⁺ out, 2 K⁺ in (active transport, uses ATP) Leakage channels: K⁺ leaks out > Na⁺ leaks in Negatively charged proteins inside the neuron C2.2.3: Nerve Impulses as Action Potentials Action potential = rapid change in membrane potential in response to a stimulus. Two phases: Depolarization: Na⁺ channels open → Na⁺ enters Inside becomes positive (up to +40 mV) Repolarization: Na⁺ channels close, K⁺ channels open K⁺ leaves → inside becomes negative again Often followed by hyperpolarization before restoring –70 mV. C2.2.4: Speed of Nerve Impulses Myelin sheath increases speed: Acts as insulation, prevents ion leakage Saltatory conduction: impulse jumps from node to node (Nodes of Ranvier) Unmyelinated ...