Spinal Cord White Matter - Anatomy & Functions
Bipolar Neurons – Structure and Functions
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Neurons that have two cytoplasmic extensions attached to their
cell body are structurally classified as bipolar.
- One process serves as the
axon and the other the
dendrite. Both processes can have many smaller branches.
- Bipolar neurons are found in the retina of the eye, roof of the nasal cavity, and inner ear. They are always sensory and carry information about vision, olfaction, equilibrium, and hearing.
- In the eye, bipolar neurons form the middle layer of the
retina.
- Here they
conduct impulses from photoreceptors (rods and cones) to ganglion cells.
- The ganglion cells then carry the visual signals to the brain via the optic nerve.
- The bipolar neurons in the nasal cavity are found in the
olfactory mucosa where they serve as receptors.
- When odorants are
drawn into the nasal cavity, they bind to cilia that extend from the dendritic ends of the receptors.
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- In response,
impulses are generated in the axons of the bipolar neurons. The axons carry the impulses through holes in the cribriform plate of the skull to the olfactory bulbs of the first cranial nerve.
- In the
inner ear, bipolar neurons make up the vestibular and cochlear branches of the vestibulocochlear nerve (cranial nerve VIII).
- The
vestibular branch carries signals into brain about balance (equilibrium).
- The
cochlear branch carries signals about hearing.


