BSC2086 Test 1 Study guide Lesson 1 Check off list nervous system o Afferent Describe the differences between the afferent and efferent divisions of the Sensory Receptors they detect stimuli Specialized cells that monitor specific conditions in the body or external environment When stimulated a receptor passes information to the Central Nervous System CNS in the form of action potentials along the axon of a sensory neuron they are sensory neurons relay the info down their axons Sensory pathways nerves nuclei and tracts that deliver sensory information to the Central Nervous System Deliver somatic and visceral sensory information to their final destinations inside the CNS using nerves axon bundles in the Peripheral Nervous System PNS Nuclei cell bodies located in the CNS Tracts axon bundles in the CNS Nuclei contains the cell bodies of motor neurons Motor tacts and nerves carries commands to effectors muscles and glands Somatic motor portion of the efferent division controls peripheral effectors Somatic motor commands travel from motor center in the brain along somatic motor pathways of motor nuclei tracts axons in the CNS nerves axons in the PNS o Efferent The Somatic nervous system SNS is comprised of motor neurons and pathways that control skeletal muscles o In summary the afferent sends sensory information to your brain and the EFFerent sends commands to the body to EFFECT the body Describe the types of stimuli that are detected by our general senses and special senses o General senses Temperature Pain Touch Pressure Vibration Proprioception monitors the position and movements of skeletal muscles and joints o Special senses Olfaction smell Gustation taste Vision Equilibrium balance Hearing Pathways for Equilibrium Sensations 1 Vestibular receptors Activate sensory neurons of vestibular ganglia Axons form vestibular branch of vestibulocochlear nerve VIII Synapse within vestibular nuclei 2 Four functions of Vestibular Nuclei Integrate sensory info about balance and equilibrium from both sides of the head Relay info from vestibular complex to cerebellum Relay information from vestibular complex to cerebral cortex Provide conscious sense of head position and movement Send commands to motor nuclei in brain stem and spinal cord Cochlear duct receptors provide sense of hearing Auditory ossicles convert pressure fluctuation in air into MUCH GREATER PRESSURE FLUCTUATIONS in perilymph of cochlea Frequency of sound is determined by WHICH PART of cochlear duct is stimulated Intensity volume is determined by NUMBER of hair cells stimulated Pressure waves consist of regions where air molecules are crowded together Wavelength Distance between two adjacent wave troughs Pitch our sensory response to frequency Six steps of sound transduction 1 Air pressure taps the tympanic membrane 2 Vibration of tympanic membrane causes vibration of malleus incus and stapes to amplify sound 3 Oval window vibrates and pushes the perilymph in the scala vestibuli Pressure of perilymph moving through the scala vestibuli and into scala Auditory pathway Cochlear branch tympani is relieved by bulging of the found window 4 Movement of perilymph in scala tympani distorts basilar membrane High frequency sounds vibrate basilar membrane closer to oval window low frequency sounds vibrates farther away 5 Movement of basilar membrane moves hair cells in relation to tectorial membrane bends stereocilia of hair cells releases neurotransmitter NT from hair cell 6 NT stimulates sensory neuron to send action potentials through cochlear branch of vestibulocochlear nerve Formed by afferent fibers of spiral ganglion neurons Enters medulla oblongata Synapses at dorsal and ventral cochlear nuclei Information crosses to opposite side of brain and ascends to inferior colliculus of midbrain Synapse in medial geniculate nucleus of thalamus Projection fibers deliver info to auditory cortex of temporal lobe of both hemispheres Reduces impact of damage to a cochlea or its ascending pathway Ascending auditory sensations Hearing range From softest to loudest represents a trillionfold increase in power Young children have greatest range o What is the difference between these two senses The general senses occur all over the body you feel pain on your hand and your knee Special senses occur in their specific special organ you can see with your eyes but not with your ears They are provided by special sensory receptors Special sensory receptors are located in sense organs such as the eye or ear and are protected by surrounding tissues Explain the difference between sensation and perception o Sensation The arriving info from the senses Stimulation of a receptor produces action potentials along the axon of a sensory neuron The frequency and patter of action potentials contain information about the strength duration and variation of the stimulus o Perception Conscious awareness of a sensation Your perception of the nature of a stimulus DEPENDS ON THE PATH it takes inside the CNS o Sensation comes for the sensation then perception comes from the brain Explain why receptor specificity and the size of the receptive field are important in stimulus detection and localization o Receptor specificity each receptor has a characteristic sensitivity your hands do not smell nor taste etc o Receptive field Area monitored by a single receptor cell the larger the receptive field the more difficult it is to localize a stimulus o This is important because certain parts of the body are more sensitive than others In lab we showed this by doing the two point experiment where you had to identify when you could feel two points It is important that some parts of the body are more sensitive than other because they need to be for our safety Our hands come in contact with a lot more dangerous things than our back does so it makes more sense that they would have smaller receptive fields and therefore be able to detect more specific stimuli Explain how specific stimuli are relayed to the central nervous system what is labeled line o An arriving stimulus reaches cortical neurons via the labeled line o Labeled line link between receptor and cortical neuron o Each labeled line carries info about ONE modality form such as physical force like pressure dissolved chemicals sound light Describe adaptation and how it can affect our perception of a stimulus o Adaptation Reduction in sensitivity of a constant stimulus Your nervous system quickly adapts to stimuli that are painless and
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