pwerpint - Click to edit Master subtitle style 7/12/11...

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Unformatted text preview: Click to edit Master subtitle style 7/12/11 Special Senses 7/12/11 Stimulus/Receptor A stimulus is sensory input that causes changes within the body pain, heat, pressure, sound Receptors are specialized structures that receives stimulus and converts it to another form of energy transduction Receptors may be simple bare nerve endings or complex such as sense organs 7/12/11 Stimulus/Receptor Sensory receptors transmit 4 kinds of information 1 . Modality type of stimulus such as vision, pain 2. Location which nerve fibers are sending signals to the brain Receptive field Intensity sound may be loud or soft/light maybe bright or dim Duration how long a stimulus lasts; when the stimulus is prolonged, the firing of the neuron gets slower and become less aware of the stimulus - adaptation 7/12/11 Classification of Receptors 1 . Stimulus modality Thermoreceptors Chemoreceptors Nociceptors Photoreceptors Mechanoreceptors 2 . Origin of stimulus Exteroceptors Interoceptors Proprioceptors 7/12/11 Somatic Sensation Originate from receptors present at more than one location in the body Temperature, pain, touch, vibration, awareness of body movements Essential in helping to coordinate movements, avoid dangers and maintain body temperature Located throughout the body in the skin, joints, skeletal Parts of the body with the greatest sensitivity involve more neurons 7/12/11 Special Senses Special senses restricted to particular areas of the body Taste tongue Smell nose Hearing ear Balance ear Vision - eye 7/12/11 Nociceptors Pain receptors Pain is adaptive and necessary sensation Two types of nociceptors Myelinated pain fibers; fast pain sharp pain, localized stabbing pain Non-myelinated pain fibers; slow pain dull, diffuse pain Injured tissues release chemicals that 7/12/11 Nociceptors Pain signals reach brain via 2 routes From head brain stem by 4 cranial nerves to pons then descend to medulla oblongata; then to thalamus and cerebral cortex From neck and below travel by 3 ascending spinal cord tracts to thalamus then to cerebral cortex 7/12/11 Nociceptors Referred Pain Pain from visceral is often misinterpreted as coming from skin Example pain from heart attack along left shoulder and down medial side of left arm Referred pain is convergence of neural pathways; nerve input from heart and skin converge on same spinal interneurons Then input goes from thalamus to cerebral cortex Pain modulation 7/12/11 Nociceptors 7/12/11 Chemoreceptors Respond to chemicals in an aqueous environment Receptors are excited by food chemicals in saliva ; excited by airborne chemicals that dissolve in mucus The receptors for taste and smell complement each other and respond to many of the same stimuli 7/12/11 Taste Chemoreceptors...
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pwerpint - Click to edit Master subtitle style 7/12/11...

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