Olfactory pathway Domina Petric MD Introduction The olfactory
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Olfactory pathway Domina Petric, MD
Introduction • The olfactory mucosa contains the olfactory receptor neurons that are responsible for scent transduction. • The transduction occurs in the olfactory receptors located on cilia at the ends of the olfactory receptor neurons. 12/21/2021 copyright 2006 www. brainybetty. com 2
The olfactory epithelium • The olfactory epithelium includes several distinct cell types. The most important of these is the olfactory receptor neuron: • a bipolar cell that gives rise to a small in diameter, unmyelinated axon at its basal surface • axon transmits olfactory information centrally 12/21/2021 copyright 2006 www. brainybetty. com 3
The olfactory cilia • At its apical surface, the receptor neuron gives rise to a single process. • The process expands into a protrusion from which several microvilli, olfactory cilia, extend into a thick layer of mucus. • Two other cell classes are also in the olfactory epithelium: basal cells and sustentacular (supporting) cells. 12/21/2021 copyright 2006 www. brainybetty. com 4
The oflactory receptors • Olfactory receptors are protein molecules attached to the olfactory receptor neurons. • There about 1, 000 kinds of olfactory receptors. • All the olfactory receptors are the same on each olfactory receptor neuron. 12/21/2021 copyright 2006 www. brainybetty. com 5
Passive vs. assisted pathway Odorant molecules can reach the olfactory receptors via a passive pathway or an assisted pathway. 12/21/2021 copyright 2006 www. brainybetty. com 6
The passive pathway Molecules reach the olfactory mucosa via inhaled air. 12/21/2021 copyright 2006 www. brainybetty. com 7
The assisted pathway The molecules attach to an olfactory binding protein that transports them directly to the olfactory receptors. 12/21/2021 copyright 2006 www. brainybetty. com 8
The electrical signal is sent via the axons of the olfactory neurons to structures called glomeruli on the left and right olfactory bulbs. 12/21/2021 copyright 2006 www. brainybetty. com 9
http: //archive. cnx. org 12/21/2021 copyright 2006 www. brainybetty. com 10
The olfactory pathway • Information is conducted from the olfactory bulbs by the lateral olfactory tract to the primary olfactory cortex. • it goes to the thalamus (mediodorsal nucleus) and on to the orbito-frontal cortex. • Here the conscious smell perception occurs. 12/21/2021 copyright 2006 www. brainybetty. com 11
Limbic system The limbic system is involved in the perception of emotions and is responsible for the "affective" component of smell. 12/21/2021 copyright 2006 www. brainybetty. com 12
Literature • http: //www. ucalgary. ca • http: //archive. cnx. org • https: //www. ncbi. nlm. nih. gov/b ooks/NBK 10896/ (Neuroscience, 2 nd edition) 12/21/2021 copyright 2006 www. brainybetty. com 13