Quick Facts
A dendrite is one of the threadlike extensions of the cytoplasm of a neuron, which typically branch into tree-like processes. In unipolar and bipolar neurons, there is a single dendrite, which proximally resembles an axon but branches distally; in multipolar neurons there are many short, branching dendrites. Dendrites form most of the receptive surface of a neuron (Dorland, 2011).
Related parts of the anatomy
Structure and/or Key Features
Dendrites are a component of olfactory sensory neurons. Each dendrite extends from the cell body to the mucus layer overlying the olfactory epithelium. Within the mucus layer, each of these dendritic ends broadens, forming a characteristic knob-like configuration from which up to 20 cilia, or olfactory hairs, diverge from and extend parallel to the epithelial surface. These cilia increase the surface area available for the membrane of the olfactory sensory neurons to identify odor molecules in the mucus layer (Standring, 2016).
Inhaled airborne odorant molecules are dissolved in the mucus that overlies the olfactory epithelium and bind to odorant-binding proteins. These proteins convey the odor molecules to the cilia of the dendrites where they bind and activate designated receptors on the dendritic cell membranes. Sensory information is subsequently conveyed to the cell body of the olfactory sensory neuron, and on to the olfactory bulb and cerebral cortex (Longstaff, 2005).
Anatomical Relations
Olfactory sensory neurons are bipolar neurons that are situated within the olfactory epithelium. Each neuron has two ends. One end has a 2 μm in diameter solitary unbranched dendrite, which extends inferiorly towards the epithelial surface. The other end has a 0.2 μm in diameter unmyelinated axon, which extends superiorly, and traverses the basement membrane on its way to the lamina propria (Standring, 2016). Their cell body lies interposed between the axon and the dendrite in the middle segment of the olfactory epithelium.
Function
The dendrites are key components of the olfactory sensory neurons that extend towards the epithelial surface. The cilia present on the ends of the dendrites increase the surface area available for the olfactory sensory neuron membrane to identify odor molecules in the mucus layer that overlies the olfactory epithelium (Standring, 2016).
Clinical Correlates
—Anosmia
References
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Longstaff, A. (2005) Neuroscience. BIOS instant notes 2nd edition: Taylor & Francis.
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edition: Elsevier Limited.
