BIOLOGY 225 Lecture Notes - Lecture 14: Pseudounipolar Neuron, Color Vision, Nociceptor
Document Summary
Sensory receptors: free dendrite endings - ex. Pain and temp receptors: dendrites endings embedded in nonneural tissue pressure tissue, form synapse w other neurons photoreceptors, modified epithelial cells activate sensory neurons, functional categories. Chemoreceptor, photo-, thermo-, mechano- (sensitive to pressure change), nociceptors (pain receptors; have higher activation threshold than other skin receptors: sensory receptor neuron pseudounipolar neuron. Allow us to perceive each sensation individually, as long it reaches the threshold level: the frequency of action potential determines magnitude of perception. Vision: the vertebrate (camera) eye, rod cells. About 125 million cells: cone cells. Not as light sensitive; provide color vision. About 6 million cells: rods and cones. Opsin + retinal more photosensitive and present in rods; rod cells are more functional in dim light: retinal. In dark: 11-cis; causes bend at carbon and can bind to opsin molecule. Rhodopsin (opsin + rhodopsin)- present in cones and allows for color vision.
