Olfactory, Gustatory Objectives: For each sense identify… specialized organs, anatomy receptor structure and specializations receptor signal transduction mechanism coding of intensity and duration pathway of conduction to the CNS

Olfaction Sense organs: nose & olfactory epithelium Receptor type: neuron w/ memb. G-proteins Receptor signal transduction mechanism Coding of intensity and duration Pathway of conduction to the CNS Coding for perceived sensation - receptors are specific for only a few ‘smells’

Olfaction Sense organs: nose & olfactory epithelium Olfactory area in humans is about 2.5 cm 2 w/ approx. 5 million sensory receptor cells. Recognize thousands of odors.

Neuronal receptor synapses with CN I - goes to olfactory cortex in medial temporal lobe

Olfactory receptors are specific to a few molecules G-proteins - bind one or a class of molecules cAMP is second messenger in some receptors …….leading to Na+ channel opening Receptor : neuron w/ membrane G-proteins

The receptors are located randomly in the epithelium, each neuron has its own type of receptor IMDJSLDFYFMDLDSUDKDKFIGOTPRSTUTDI receptors odorants But their axons cluster by receptor type (thus, by odor) in the olfactory bulb “citrus”“moldy”“wet grass”

Gustation - the sense of taste Sense organs: tongue & throat, taste buds Receptor type: non-neuronal

Transduction: Each taste has a specific mechanism to depolarize cell,  ICF Ca 2+, release NT Salty – Na + influx Sour – H +, block K + Bitter – G-protein:IP 3 Sweet – G-protein: cAMP, block K +

Taste path: CN VII (facial) CN IX (glph.) CN X (vagus)  medulla  thalamus  gustatory cortex