Special Senses and Endocrine Note Card

Olfaction: organs (olf ep + lamina) on either side of the nasal septum. Cells = receptor. Olfactory epithelium contains receptor cells, sup cells, and regen basal cells. Covers inf surface of crib plate. Underlying lamina propria-areolar tissue, num. BV, nn, olf glands. Their secretions abs h2o and form mucus. Air swirls in nasal cav (concha+meatus), turbulence brings air cmpds to olf orgs. H2o sol and lipid sol mats can diffuse into overlying mucus can stim receptors. Recpt=highly mod neurons. Knob projects beyond epithel. 20 cilia shaped dendrites extend into mucus. Exposed to odorants (sm org). Odorant binds to g prot recep in plasma membrane of an olf recep cell dendrite. Activation of aff fiber does not guarantee perception. Convergence takes place on pathway, inhib at intervening syns can prev sensations from reaching olf cortex (cerebral hemi). Central adaptation=less awareness. Receps adapt little. Bundles go through crib plate to reach olf bulb of cerebrum. 1st syn. Eff fib innerv neurons of olf bulb,. Provides cenral adap. Leave bulb to olf cort, hypothal (assoc w mem), and limbic. Diff smell=odorant attach pattern. Odorant binds, activate prot, atp-camp, camp binds closed na, open, na in, depol membrane. Reaches cerebral cortex directly. Other sens are relayed by thalamus. Distinct 2-4k stim. No struct diff on recep cell. 50 primary smells. Gen potential. Adenyl cyclase activates atp to camp. CNS interps cell by pattern of recep activity. Odorants in low concs. Axons from olf ep collect into budnles that reach bulb. Leaving bulb travel olf tract to cort. Etc. Gustation: organ=tongue. Cell=taste bud=recep+spec epithel. 2 sens: sour bitt, salt, sweet, umami, water. Unexitable membs, form syns with processes of sens neurons. Recep cell undergoes a graded depol triggers rel of chem transmitters at syn. Trans depol sens neuron, gen potential, ap prop to cns. Sun involved, dyn delay. Mod of sensitivity of recep by presyn facil or inhib. 90% gust cells...