PSL300H1 Lecture Notes - Lecture 8: Olfactory Bulb, Olfactory Receptor, Olfactory Nerve
Document Summary
Chemoreception evolutionarily old: bacteria use it to guide their movements; animals without brains use it to find food and mates. Chemoreception may have evolved into chemical synaptic communication. This epithelium lies at the top of the nasal cavity, covering ~3 cm2 each of the 2 sides. It contains ~10 million receptor cells in total. No one knows why, but the richness of its color correlates with olfactory sensitivity: in us it is pale yellow, in 1 cats a dark mustard brown . Each cell has a single dendrite that extends into the olfactory epithelium. There it branches to form non motile cilia (cells dont use atp to move cilia around) that increase the surface area of the cell, so it has a greater chance of catching odorant molecules. Each receptor cell has (many copies of) one type of odorant receptor molecule on its membrane. We have ~400 kinds of receptor cell, i. e. ~ 400 primary odors .
