PSL300H1 Lecture Notes - Lecture 27: Olfactory Bulb, Chemoreceptor, Olfactory Nerve
Document Summary
Evolutionary old: bacteria use chemoreception to guide movement, animals w/o brains use chemoreception to find food & mates. May have evolved into chemical synaptic communication. In the olfactory epithelium: at the top of the nasal cavity. Covers ~ 3cm2 of space on each side (2 sides total 6 cm2 total) ~ 10 million receptor cells in total. Pigmented epithelium: richness of colour olfactory sensitivity, pale yellow in humans not sensitive, dark mustard brown in cats much more sensitive. Ciliated neurons: has single dendrite that extends into olfactory epithelium, in the olfactory epithelium branches nonmotile cilia, increases surface area of the cell higher chance of catching odorant molecule. Each receptor type specifically for one type of odorant molecule. Humans: ~400 receptor cell types ~400 primary odors . Extremely sensitive: some can detect 1 single molecule (receptor threshold, need ~40 cells to react to perceive of the smell (perceptual threshold)
