lecture 14-sensory II chemoreception and auditory system

Olfactory system gustatory system auditory system

Anatomy of Olfactory neurons

• Cilia

  • (act like dendrite points downward) into mucous layer

  • have odorant receptor protein

• Axon

  • project upwards through the ethmoid bone

  • synapse in olfactory bulb on 2th sensory neuron

signal transduction in the Olfactory system

1. odor molecule binds to G protein-coupled receptor

2. activated G protein (GOIF) activates Adenylyl cyclase

3. AC converts ATP to cAMP

4. cAMP opens cyclic nuclotide-gated Na channel

5. sufficient receptor potential produces Action potential at the axon hillock

Olfactory Sensory signal Pathway

olfactory neuron → Cranial Nerve I → Olfactory tract → olfactory cortex → (both) cerebral cortex and limbic system

• smell is linked to emotion and memory

how many taste cell in one taste bud?

50-150 cells

characteristic about tase cell

• taste cells are non-neuronal (specialized cell) , each is sensitive to a particular "tastant ligand”

• tase cells are polarized

  • receptor region at apical membrane (facing the lumen)

  • communicates with primary sensory neuron at basal membrane

• intracellular signal pathway is different for each type of taste cell.

what are the types of taste cell ?

• Type I support cells

• Type II receptor cell

  • Sweet, umami, bitter

• Type III

  • Sour