Olfactory pathway Domina Petric MD Introduction The olfactory

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Olfactory pathway Domina Petric, MD

Olfactory pathway Domina Petric, MD

Introduction • The olfactory mucosa contains the olfactory receptor neurons that are responsible for

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

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

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

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

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

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

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

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

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

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

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.

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