The nervous system is built from specialised cells that coordinate perception, movement, and thought. Neurons carry signals, while glial cells support, protect, and fine-tune neural networks so communication remains efficient and stable.

Overview: Two Major Cell Classes

Psychologists and neuroscientists focus on how cellular structure enables function: neurons are designed for rapid signalling across distance, and glia maintain the environment that makes signalling possible.

Neurons are “wired” for directional communication, with specialised regions that bias information flow from input to output.

Neurons: How Information Moves Through a Cell

Core parts and their jobs

Most neurons share the same basic architecture:

Labeled neuron diagram highlighting the major anatomical regions (dendrites, soma/cell body, axon, and axon terminals). Use it to connect each structure to its role in receiving, integrating, and transmitting signals across neural circuits. Source

• Dendrites: branching input regions that receive signals from other cells.

• Cell body (soma): integrates incoming information and supports metabolism.

• Axon: a long fibre that carries the signal away from the soma.

• Axon terminals: output endings that pass the signal to the next cell across a junction.

Signals typically travel in this sequence:

• Dendrites receive input

• Soma integrates input

• Axon conducts the message

• Terminals communicate to another neuron, muscle, or gland

What neurons transmit (without the “how” details)

At the AP level, it is essential to link structure to function: neurons transmit information using electrical activity within the neuron and chemical signalling between cells (via messenger molecules). The key idea is that neurons form networks, and behaviour emerges from patterns of activation across many connected neurons rather than from single cells acting alone.

Glial Cells: Support, Insulation, Communication, Cleanup

Neural signalling depends on a stable chemical environment, sufficient energy, and protected connections—tasks largely handled by glia.

Glia were once described as mere “support cells,” but they are active partners that influence how efficiently neural networks develop and operate.

Major functions emphasised in AP Psychology

Glial roles can be organised into four syllabus-aligned categories:

• Structure: scaffolding that helps organise neural tissue and maintain cellular health

• Insulation: creation of fatty coverings around axons that improve signal efficiency

• Communication support: regulating the local environment so neurons can signal reliably

• Waste transport/cleanup: removing cellular debris and helping maintain homeostasis

Myelin and insulation (glia as speed/efficiency boosters)

Some glia wrap axons in myelin, which helps messages travel more efficiently along the axon.

Diagram of a neuron segment with an oligodendrocyte wrapping the axon to form the myelin sheath. It visually clarifies how glial insulation is physically arranged around axons to support faster, more efficient signal conduction. Source

In the brain and spinal cord, myelin is produced by glia often called oligodendrocytes; in the peripheral nervous system, similar myelinating cells are commonly called Schwann cells.

Examples of glia you may encounter

Different glial subtypes specialise in different support tasks:

Comparative diagram of major central nervous system glial cell types—astrocytes, oligodendrocytes, microglia, and ependymal cells—distinguished by color and morphology. This supports memorizing each subtype’s “job description” (metabolic regulation, myelin production, immune cleanup, and lining fluid-filled spaces). Source

• Astrocytes: help regulate chemicals around synapses and support neurons’ metabolic needs

• Oligodendrocytes/Schwann cells: form myelin for insulation

• Microglia: assist with cleanup and immune-like protection

• Ependymal cells: help line fluid-filled spaces and support fluid-related functions

Why Neurons and Glia Matter for Behaviour

Neurons provide the signalling capacity required for sensation, movement, learning, and emotion. Glial cells make those signals possible at scale by insulating connections, stabilising the neural environment, supporting communication conditions, and transporting waste so networks can keep functioning over time.