Olfaction

What is olfaction?

The chemical sense of smell.

How many odors can humans detect?

Humans can detect several hundred thousand odors.

What percentage of odors are considered noxious?

80% of odors are considered noxious.

What is the location of the olfactory epithelium?

High in the nasal cavity around the cribriform plate of the ethmoid bone.

What are the three main types of cells in the olfactory epithelium?

Basal cells, olfactory receptor cells, and supporting cells.

What is the role of basal cells in the olfactory epithelium?

Basal cells are epithelial stem cells that become new receptor cells.

What do olfactory receptor cells bind to?

Olfactory receptor cells bind to odorants.

What type of cells are olfactory receptor cells?

Bipolar cells.

What structure forms the olfactory nerve?

The unmyelinated axons of olfactory receptor cells.

What is the function of supporting cells in the olfactory epithelium?

Support and maintain the function of olfactory receptor cells.

What is the role of Bowman's gland?

Secretes mucus in the olfactory epithelium.

What structures do odorant molecules bind to?

Cilia on olfactory receptor cells.

What is the axon path of olfactory neurons?

Axons project to the olfactory bulb.

What is the significance of the olfactory bulb?

It is where the olfactory nerves synapse with mitral and tufted cells.

What are second-order neurons in olfaction?

Mitral and tufted cells located in the olfactory bulb.

What do the bulb fibers proceed through?

The olfactory tract.

Into what two striae does the olfactory tract divide?

Medial olfactory stria and lateral olfactory stria.

What does the medial olfactory stria connect?

It reaches the opposite olfactory bulb through the anterior commissure.

Where does the lateral olfactory stria project?

To the primary olfactory cortex.

What two regions form the primary olfactory cortex?

The piriform cortex and entorhinal cortex.

What system is the olfactory system considered a subdivision of?

The limbic system.

What is the role of the piriform cortex?

It relays information to the orbitofrontal olfactory cortex.

What does olfaction uniquely do compared to other senses?

Olfaction reaches the cortex directly without synapsing with the thalamus.

What areas does olfactory information travel to from the olfactory bulb?

Orbitofrontal cortex, piriform cortex, and entorhinal cortex.

What is the anatomical significance of olfactory bulb size between species?

Relative size of olfactory bulbs varies between rat and human brains.

What is the olfactory tract's role in the brain?

Transmits olfactory information from the bulbar neurons to cortical areas.

How are action potentials generated in olfactory receptor cells?

Through membrane depolarization in response to odorants.

What ion channels are involved in olfactory signal transduction?

Ca2+, Na+, and CAMP channels.

What is the role of olfactory receptor proteins?

They bind to specific odorants and initiate signaling.

In olfaction, what is the 'dendritic process'?

The part of the olfactory receptor cell where cilia are located.

What happens to the olfactory signals after they synapse in the bulb?

They are processed and relayed to various brain areas.

What is the process of odor detection in olfactory cells?

Odorant binding triggers depolarization and action potentials.

What do the cilia on olfactory receptor cells do?

They increase surface area for odorant binding.

What type of signals do olfactory neurons send?

Electrical signals in the form of action potentials.

What effect do odorant molecules have on the olfactory epithelial cells?

They activate receptors, initiating the olfactory process.