Anatomy of a neuron | Human anatomy and physiology | Health & Medicine | Khan Academy

Summary

The video introduces the neuron as a specialized cell that communicates by receiving and transmitting signals. The illustrated neuron is a representative example; neurons can vary in shape and size.

Main Parts of a Neuron

• Soma (cell body): The central part of the neuron, containing the nucleus.
• Dendrites: Branching extensions from the soma that commonly receive signals from other neurons or sensory inputs.
• Axon hillock: The region where the soma joins the axon. Incoming signals are combined here, and sufficiently strong input can trigger an action potential.
• Axon: A long extension that carries signals away from the cell body. Axons vary in length; some are short, while others extend along the spinal column or into a limb.
• Myelin sheath: An insulating covering around portions of the axon. In the example described, it is formed by Schwann cells and helps signals travel efficiently.
• Nodes of Ranvier: Gaps between sections of the myelin sheath.
• Axon terminals: The endings of the axon, which can connect with other neurons, muscles, or other tissues.

General Signal Pathway

1. Signals arrive at the neuron, often through its dendrites. Sources may include other neurons or sensory inputs, such as molecules detected by taste receptors.
2. Incoming signals can be combined, or summed.
3. If the combined input is strong enough, it triggers an action potential at the axon hillock.
4. The action potential travels along the axon.
5. At the axon terminals, the neuron can communicate with other cells across connections called synapses, potentially triggering further activity.

These functions are general patterns rather than absolute rules; neurons can vary in structure and function.

Speakers and Sources

• Narrator/presenter: Sal Khan, identified in the video metadata as the creator.
• Other speakers or sources: None featured in the subtitles.