BIOL 240 Chapter Notes - Chapter 7: Chemoreceptor, Cyclic Adenosine Monophosphate
Document Summary
Smell: olfactory receptors are in the olfactory epithelium. Epithelium lies on top of the nasal cavity and cover 3cm^2 in each of the two sides and has 10 million receptor cells; less than vision but more than hearing (40,000) Epithelium is pigmented: richness of color correlates w olfactory sensitivity: humans have pale yellow while cats have a dark mustard brown- explains why cat have a stronger sense of smell, receptor cells are ciliated neurons. Each cell has a single dendrite that extends into the olfactory epithelium and branches to form nonmotile cili that increase the cells surface area so it has a better chance in catching odourant molecules. Largest known gene family - 1000 genes- 3-5% of the genome of vertebrates- but only around 400 are expressed in humans. When an odorant binds its receptor, it activates the a golf protein which increases camp concentration > camp gated channels open > depolarizing.
