Olfaction DLA

Question 1

Describe Chemical stimuli

Answer 1

• Olfactory stimuli are airborne molecules of our environment, entering the nasal cavity through our nostrils (orthonasal olfaction) or originating from food or drinks in our oral cavity (retronasal olfaction).
• Most odorant molecules stimulate more than just one of the approximately one thousand different types of olfactory receptor neurons. Depending on which sets of receptors are activated, we can differentiate between tens of thousands of different odorants (for example citrus, peppermint, or almond).
• But, in comparison to our sense of smell, we can only differentiate between four or five taste qualities.
• Therefore, our olfactory system contributes very much to the pleasure we experience when eating an elaborate meal.
• In addition, chemoreceptors of the trigeminal somatosensory system contribute to our sensory experience of food, including capsaicin-sensitive heat receptors (red chili pepper), menthol-sensitive cold receptors (mint) and receptors sensitive to mustard oil (wasabi, horseradish) that add pungency

Question 2

What does olfactory nerve do?

Answer 2

(CN I)→Axons of the olfactory receptor neurons

Question 3

What does the basal cell do?

Answer 3

(Stem cell)→Cell division and differentiation/regeneration

Question 4

What does the olfactory receptor cell do?

Answer 4

(Olfactory sensory receptor neuron)

Question 5

What is a supporting cell?

Answer 5

Sustentacular cell

Question 6

What is the function of cilia of olfactory cells?

Answer 6

Increase of surface area (transduction site)

Question 7

Describe olfactory signal transduction

Answer 7

• Metabotropic signal transduction
• Second messenger: cyclic AMP

Odorant molecule→Receptor binding→G-protein→Enzyme→ Second messenger→Current through ion channel→Depolarization→ Transmitter release

Question 8

What are olfactory pathways?

Answer 8

• The olfactory bulb receives input through the axons of the olfactory receptor neurons forming the olfactory nerve (CN I)
• Output neurons of the olfactory bulb run their axons through the olfactory tract and the medial and lateral olfactory stria. They synapse on structures of the limbic system and the olfactory cortex, without having passed through the thalamus (= sensory systems exception)

Question 9

Where is the olfactory cortex?

Answer 9

• Olfactory cortex areas include the piriform cortex and the entorhinal cortex