BIOL 215 Study Guide - Midterm Guide: Lateral Geniculate Nucleus, Rhodopsin, Visual Cortex
Document Summary
Only type of sensory cell that is so depolarized (resting membrane potential -35mv) Guanylyl cyclase converts gtp into a high concentration of the second-messenger cgmp. The cgmp keeps the cgmp ligand-gated channels in an open state. Ongoing influx of na+ and ca2+ (that"s why cell is so depolarized) Bipolar cells communicates directly with photoreceptors with its inhibitory synapses. After photoreceptor hyperpolarizes, photoreceptor no longer able to inhibit bipolar (glutamate) which allows bipolar cells to excite ganglion cells which allows a signal to be sent to the lgn to the occipital lobe. For cones: (for rods it"s rhodopsin instead of opsin) Retinal (derivative of vitamin a) changes conformation and dissociates from opsin. Opsin then changes shape and is able to interact with transducin (g-protein) Transducin activates cgmp-phosphodiesterase (pde), which rapidly degrades cgmp. This allows the ion channels to close, which hyperpolarizes the cell. Retinal goes back to its normal shape and reassociates with opsin.
