PHIS 206 1st Edition Lecture 8 Outline of Last Lecture I Cortical Association Areas II Memory III Amnesia IV Cerebellum V Brain Stem connects cerebellum and cerebrum VI Reticular Formation Outline of Current Lecture I Afference II Sensation v Perception III Sensory System IV Receptor Generator Potentials V How Receptors Work VI Receptor Properties VII Afferent Delivers to Brain VIII Sensory Neuron Input IX Sense Pain X Perception XI Autonomic Nervous System XII Somatic Nervous System XIII 2 Neurons Autonomic Nervous System Current Lecture I II Afference blood pressure etc brain knows it but we don t Other type carries information about the outside world sensory systems have receptors that are specialized to interact with energy and convert it to action potentials Sensation v Perception sensations raw information that comes in can have some sensations same as others These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute III IV V VI VII VIII perceptions varies b w person to person Sensory System has to interact with some energy in the outside environment sensory receptors interact with certain frequencies attuned to stimuli has to be able to convert energy into some input transducers converting environmental activities into action potentials Receptor Generator Potentials sensory receptor properties 1 interacts with some form of energy in the environment 2 acts as transducer of energy to action potentials adequate stimulus stimuli that receptors are very sensitive to How Receptors Work When stimulated Na channels in membrane opens decrease negativity of membrane potential receptor potential those receptors that are not neurons Graded stimuli present weak stimulus small change in receptor potential but no action potential have to reach threshold Most receptors frequency of action potential is related to stimulus strength Frequency coding when stimulus is strong more action potentials Ex loud sound more action potentials unit time Population coding increase strength of stimulus more neurons fire Receptor Properties adaptation continue to stimulate gradually receptors will stop responding EX Fix eyes on object w o moving head or eyes receptors respond to the rate of change of stimulus neurally mediated receptors blood pressure up when running and then adapt in a couple of minutes Over long periods of time receptors do not work Exceptions tonic receptors generate action potentials at the same level when continuously stimulated Afferent Delivers to Brain visual receptors optic nerve see light Neurons are specialized Label lined coded nature of stimulus and amplitude of stimulus referred pain direct association with label lined pain afference pathways same spinal cord brain pathways back forth Sensory Neuron Input area from which sensory neuron can be stimulated receptive fields very large present 2 stimuli far apart but still not able to tell they are 2 stimuli ears very small close able to make finer distinctions fingers sensory acuity ability to discriminate b w 2 sensory that are close by IX X XI XII XIII Sense Pain pain receptors naked nerve neurons ending in a particular location 2 Types 1 Fast Pain 1st Pain carried in A Delta neurons are mild can pinpoint sensitive to mechanical chemical 2 Slow Pain 2nd Pain carried in C Delta neurons non poorly localized pain continued until stimulated sensitive to pressure Energy in cells Ex breaking leg bone non adaptable sensors continuous pain Perception analgesia system releases opiums into brain causes pleasure pain endorphins indigenous morphin like compounds Autonomic Nervous System involuntary activities blood pressure lungs etc 2 subsections 1 Sympathetic fight or flight becomes activated 2 Parasympathetic response to non physical activity eating Somatic Nervous System makes muscles move 2 Neurons Autonomic Nervous System Parasympathetic Sympathetic Preganglionic Long ACh Short ACh Postganglionic Short ACh Long Norepinephrine
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