BCMB 230 1st Edition Lecture 11 Outline of Last Lecture I Classification of Neurotransmitters II Biogenic Amines III Drugs associated with Neurotransmitters IV Peripheral Nervous System Outline of Current Lecture I Sensory Physiology II Information We Get From Receptors III Sensory Anatomy Current Lecture I Sensory Physiology non chemical stimulus receptor signal transduction afferent pathway CNS sensation perception Sensation is the same for people it relies on the same physiological mechanisms Perception is different for people can be based on what people associate with the sensation or the context they experience with the sensation This pathway is clinically important when looking at a patient s pain pathway II Information We Get From Receptors Four Kinds stimulus type two factors that let us know stimulus type receptor type stimulated and the portion of brain stimulated Types of receptors chemoreceptors taste smell visceral sensation act very much like receptors for chemical messengers photoreceptors sense of vision mechanoreceptors respond to distortion of receptor touch stretch thermal receptors part of somatosensory tell what temperature is skin Noucereceptors specific for pain stimulus location To find where a stimulus is 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 need a receptive field area that responds to stimuli low density of receptors large receptive field high density of receptors small receptive field two stimuli on one receptive field will only feel like one stimuli ex touching difference in acuity being able to distinguish between two related stimuli stimuli that are physically close together high acuity easy to tell stimuli apart low acuity difficult to tell stimuli apart Sensitivity what s the smallest stimulus that you can detect ex smallest amount of light the lightest touch determined by the graded potential at the receptor reaching the threshold or not confused sometimes with acuity What part of the brain it goes to body map on the brain that tells you where the stimulus is located face and fingers have higher acuity have more receptors everywhere else has a lower acuity has less receptors Lateral inhibition have inhibitory pathways connecting afferent pathway stimulus tells adjacent receptors not to respond allows you to key on the center of the stimulus stimulus strength To tell how big a stimulus is the graded potential at the receptor detect the action potential signal strength is frequency of action potential which usually depends on size of graded potential which depends on the size of the stimulus sensory recruitment signal recruits nearby sensors in response to the same stimuli stimulus duration To tell stimulus duration depends on type of receptor you have two main classes sensory adaptation happens over a short period of time to an individual rapidly adapting receptor get action potential right when you get stimulus and then when it is turned off slowly adapting cluster of action potentials at first that is readily steady ex pain information touch smell III Sensory Anatomy Hair cell sensory neuron example of a mechanoreceptor in the ear open mechanically gated K channels K goes into the cell leads to depolarization normally potassium ions go out causing hyperpolarization this is specific for this location only opens Ca 2 channels which depolarizes the cell further releases signal appears in inner ear responds to sound Three main anatomical areas of the ear Vestibular apparatus has two main parts 1 vestibule utricle saccule 2 semicircular canals x y z 3 Cochlea In the vestibule have otolithic organ Three semicircular canals have an ampulla at the base where the hair cells are