BIOC32H3 : Sensory systems summary
Document Summary
There are sensory receptors for many different modalities. There are receptors that sense, for example, chemical stimuli (chemoreceptors), mechanical movement (mechanoreceptors), light (photoreceptors), temperature (thermal receptors), noxious substances (nocioceptors), etc . In general, a receptor protein on a sensory (receptor) cell detects the stimulus. This usually causes the opening of ion channels either alone or in conjunction with activation of second messenger systems. Ultimately there is a change in membrane potential that leads a signal being sent to an integrating centre in the brain. The sensory receptor itself may send the signal to the brain (i. e. , sensory neurons) or the sensory cell may release neurotransmitters onto another neuron (interneuron) that conveys the signal to the brain (i. e. , epithelial sensory receptor cells). One important integrating centre is the nucleus of the solitary tract (nucleus tractus solitarius; nts) located in the brainstem at the junction between the medulla oblongata and the spinal cord.
