The Nervous System, Part 2 - Action! Potential!: Crash Course Anatomy & Physiology #9

Action Potential

Electrical signal traveling along neurons.

Neurons

Cells transmitting electrical and chemical signals.

Resting Membrane Potential

Voltage difference across neuron membrane (~ -70mV).

Sodium-Potassium Pump

Transports 3 Na+ out, 2 K+ in.

Depolarization

Na+ influx makes neuron more positive.

Threshold

Voltage level (~ -55mV) for action potential initiation.

Repolarization

Restoration of negative charge after depolarization.

Hyperpolarization

Temporary increase in negativity (~ -75mV).

Propagation

Action potential travels along axon in waves.

Myelin Sheath

Insulation speeding up signal transmission.

Saltatory Conduction

Action potentials jump between Nodes of Ranvier.

All-or-None Principle

Action potential occurs fully or not at all.

Refractory Period

Time during which neuron cannot fire again.

Synaptic Transmission

Release of neurotransmitters across synapse.

Neurotransmitters

Chemical signals initiating action potentials in receiving neurons.

Voltage-Gated Channels

Channels that open/close in response to voltage changes.

Axon Terminal

End of neuron where neurotransmitters are released.

Chemical Signals

Signals occurring between neurons at synapses.

Neural Communication

Process involving electrical and chemical signaling.

Nodes of Ranvier

Gaps in myelin sheath for saltatory conduction.

Schwann Cells

Cells producing myelin in the peripheral nervous system.

Oligodendrocytes

Cells producing myelin in the central nervous system.