Give an example of a polar neuron

Neurons vary in shape and size, but are broadly grouped as unipolar, bipolar, multipolar, and pseudounipolar.

Multipolar neurons

• Have one axon and many dendrites (with branches), so they can integrate lots of inputs.
• Axon: carries action potentials away from the cell body to other cells.
• Dendrites + soma: main receptive zone.
• Most common neuron type; abundant in the brain and spinal cord.
• Example: Purkinje cells in the cerebellum—many dendritic branches, one axon.

Unipolar neurons

• Have a single process emerging from the soma.
• Classic unipolar neurons are not found in vertebrates (seen in insects for activating muscles/glands).

Bipolar neurons

• Have one axon and one dendrite.
• Example: retinal bipolar cells—relay signals from photoreceptors to ganglion cells (which send signals to the brain).

Pseudounipolar neurons

• Start as bipolar in development, then processes fuse so one process leaves the soma and splits into two branches.
• Common among sensory neurons: one branch receives peripheral input; the other carries impulses to the spinal cord.

A neuron’s structure is closely tied to its function—how it receives, integrates, and transmits information.