BIOL 2312 Chapter 44.1-44.3: Chapter 44.1- 44.3 Sensory Systems
7 Feb 2017
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Sensory receptors detect both external and internal stimuli. Mammalian hearing converts airborne stimulus into a waterborne one. Does this as evolutionary run off-- most of the external receptors evolved in water before land. Vertebrate sensory systems that function well in water: Cannot function in the air and thus not found in terrestrial animals. Terrestrial sensory systems that work well for land. Receptors categorized by the type of stimulus that best stimulates dendrites: React to bending and stretching of the sensory neuron in response to changes in temperature, or chemicals in the extracellular fluid. Sensory information is conveyed in a 4 step process: 1. ) stimulation: a physical stimulus impinges on a sensory neuron or an associated but separate receptor. Transduction: the stimulus energy is transformed into graded potentials in the dendrites of the sensory neuron. Transmission: action potentials develop in the axon of the sensory neuron and are conducted to the cns along an afferent nerve pathway.
