Sensory Receptors PDF

39 Sensory Receptors  Sensory perception : reception and perception of information from both inner medium/movement , pain) and outer medium (vision , hearing * In biophysics receptors are energy transductors...

39 Sensory Receptors  Sensory perception : reception and perception of information from both inner medium/movement , pain) and outer medium (vision , hearing * In biophysics receptors are energy transductors Types of Sensory Receptors 1) According to their 2) According to their 3) According to the acting energy complexity place of origin and the way of their receptions. free · mechanoreceptors · nerve ending (pain) · Telereceptors : detect thermoreceptors stimuli from distance · · sensory bodies (sight-hearing-smell · photo receptors (cutaneus sensation) · Exteroreceptors : detect · sensory cells stimuli by touching/contacting. (sensory organs , smell-taste ) (Cutaneus... sensation , taste · Interoreceptors : pain in internal organs , so that stable environment · Proprioreceptors : detection of position of movement (like in muscles/ tendons) Receptor Cells and Their Common Features Consist : outer · of 2 segments Segment , which receives the stimulus and inner segment which has mitrochondria lenergy). > - when stimulus activates the euter segment > - ion chanels on the cell membrane open a close. This leads to flow of ions into or out of the cell > - causing change in membrane potential (t)()degisiyer. This change is called receptor potential When > - the receptor potential is large enough + depolarization can happen (inside being more + charged > - When receptor potential reaches the treshold-> action potential can happen. (-5SmV) Receptor Potential · Receptor potential is the depolarization change in the cell. Stimuli comes - opens channels+ receptor potential occurs. · · Receptor current : flew of ions. * Intensity of stimulus is proportional to receptor potential / receptor. current Cintensity 4 , recept potential 1)  Weber-Fechner and Steven's Law log (Is) off Weber-Fecher intensity Im k : · = sensation increases with intersity of stimulus non-linearly. IR= Int of sensation. Is = Int of stimulus 3 Steven : this relation can be expressed exponentially. Is so he explains the relation Ip = k2. better at very low or high Stimulus intensities. a> exponent specific for - sense modality (low , hish) · ky , ke > - proportionality constants Adaptation · If intensity of a stimulus stays constant for a long time , the excitability of most receptor decreases Organism. can respond efficiently to relevat or chaging aspects of their environment instead of constantly acting to stable stimuli. > - The adaptation degree is different for different cells. Eg its. degree is low in pain sensation as a result of protection mechanism.