Neurons and Nervous Systems

Neurons and Nervous Systems Neuron structure Generating and Conducting Nerve Impulses Synapses

Identify: Dendrites Form = Function Nucleus Cell body (soma) Axon Figure 44.2 Neurons (Part 1) Identify: Dendrites Nucleus Cell body (soma) Axon Synapse Myelin? Axon terminal Form = Function

Nervous Systems: Cells and Functions Myelin is the covering produced by Schwann cells and oligodendrocytes.

Figure 44.3 Wrapping Up an Axon

Neurons: Generating and Conducting Nerve Impulses The difference in voltage across the plasma membrane of a neuron is called its membrane potential. In an unstimulated neuron, the voltage difference is called a resting potential. The membrane potential of a resting axon is about –60 millivolts (mV). The inside of the cell is more negative than the outside.

Figure 44.5 Ion Pumps and Channels

Figure 44.4 Measuring the Resting Potential (Part 2)

Neurons: Generating and Conducting Nerve Impulses An action potential is the sudden and rapid reversal in voltage across a portion of the plasma membrane. For 1 to 2 milliseconds, the inside of the cell becomes more positive than the outside. Nerve impulses are action potentials that travel along axons.

Figure 44.9 The Course of an Action Potential

Figure 44.10 Action Potentials Travel along Axons (Part 1)

Figure 44.10 Action Potentials Travel along Axons (Part 2)

Figure 44.10 Action Potentials Travel along Axons (Part 3)

Figure 44.13 The LAST STEP: the Synapse

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