A P STUDY GUIDE EXAM 1 Lesson 1 nervous system 1 Describe the differences between the afferent and efferent divisions of the a Afferent Division of the Nervous System involves i Receptors detects the stimuli ii Sensory neurons relays the information down their axons iii Sensory pathways nerves nuclei and tracts that deliver sensory information to the CNS b Efferent Division of the Nervous System involves i Nuclei contains the cell bodies of motor neurons ii Motor tracts and nerves carries commands to effectors muscles and glands 2 Describe the types of stimuli that are detected by our general senses and special senses What is the difference between these two senses a Sensory Receptors specialized Senses i Specialized cells that monitor specific conditions in the body or external environment ii When stimulated a receptor passes information to the CNS 1 In the form of action potentials along the axon of a sensory neuron b Sensory Pathways i Deliver somatic and visceral sensory information to their final destinations inside the CNS using 1 Nerves axon bundles in the PNS 2 Nuclei cell bodies located in the CNS 3 Tracts axon bundles in the CNS c Somatic Motor Portion of the Efferent Division i Controls peripheral effectors d Somatic Motor Commands i Travel from motor centers in the brain along somatic motor pathways of 1 Motor nuclei 2 Tracts axons in the CNS 3 Nerves axons in the PNS e Somatic Nervous System SNS i Motor neurons pathways that control skeletal muscles f General Senses i Describe our sensitivity to ii Temperature iii Pain iv Touch v Pressure vi Vibration vii Proprioception monitors the position and movements of skeletal muscles and joints g Special Senses i Olfaction smell ii Vision sight iii Gustation taste iv Equilibrium balance v Hearing vi The Special Senses 1 Are provided by special sensory receptors vii Special Sensory Receptors 1 Are located in sense organs such as the eye or ear 2 Are protected by surrounding tissues 3 Explain the difference between sensation and perception a Sensation b Perception i The arriving information from these senses i Conscious awareness of a sensation 4 Explain why receptor specificity and the size of the receptive field are important in stimulus detection and localization a The Detection of Stimuli b Receptor specificity i Each receptor has a characteristic sensitivity your hands do not smell nor taste your eyes do not hear etc i Area is monitored by a single receptor cell ii The larger the receptive field the more difficult it is to localize c Receptive field a stimulus is labeled line 5 Explain how specific stimuli are relayed to the central nervous system what a Arriving stimulus reaches cortical neurons via labeled line link between receptor and cortical neuron i Each labeled line carries info about 1 modality form such as 1 Physical force such as pressure 2 Dissolved chemical 3 Sound 4 Light 6 Describe adaptation and how it can affect our perception of a stimulus What is the difference between central and peripheral adaptation a Adaptation i Reduction in sensitivity of a constant stimulus ii Your nervous system quickly adapts to stimuli that are painless and constant 1 Ex New smells rings earrings iii Stimulation of a receptor produces action potentials 1 Along the axon of a sensory neuron iv The frequency and pattern of action potentials contain information 1 About the strength duration and variation of the stimulus v Your perception of the nature of that stimulus depends on the 7 Explain the difference between tonic and phasic receptors path it takes inside the CNS a Tonic receptors i Are always active ii Show little peripheral adaptation iii Are slow adapting receptors 1 Ex Pain receptors nociceptors remind you of an injury long after the initial damage has occurred b Phasic receptors i Are normally inactive ii Become active for a short time whenever a change occurs iii Are fast adapting receptors iv Provide information about the intensity and rate of change of a stimulus v Ex Thermoreceptors detect rapid changes in temp 8 Describe the three broad categories of sensory receptors a Exteroceptors provide information about the external environment b Proprioceptors report the positions of skeletal muscles and joints i Provide a purely somatic sensation ii No proprioceptors in the visceral organs of the thoracic and abdominopelvic cavities 1 You cannot tell where your spleen appendix or pancreas is at the moment c Interoceptors monitor visceral organs and functions 9 Describe the four types of general sensory receptors a 1 Nociceptors Pain Receptors are common In the superficial portions of the skin In joint capsules i ii iii Within the periostea of bones iv Around the walls of blood vessels v Analgesia inability to feel pain vi Hyperalgesia increased sensitivity to pain vii May be sensitive to 1 Temperature extremes 2 Mechanical damage 3 Dissolved chemicals such as chemicals released by injured cells viii Are free nerve endings with large receptive fields 1 Branching tips of dendrites 2 Not protected by accessory structures 3 Can be stimulated by many different stimuli 4 Two types of axons Type A large myelinated and Type C small unmyelinated fibers ix Myelinated Type A fibers 1 Carry sensations of fast pain or prickling pain such as that caused by an injection or a deep cut 2 Sensations reach the CNS quickly and often trigger 3 Relayed to the primary sensory cortex and receive somatic reflexes conscious attention x Type C fibers 1 Carry sensations of slow pain or burning and aching pain and thalamus 2 Cause a generalized activation of the reticular formation 3 You become aware of the pain but only have a general b 2 Thermoreceptors idea of the area affected i Also called temperature receptors ii Are free nerve endings located in 1 The dermis 2 Skeletal muscles 3 The liver 4 The hypothalamus overall regulation of body temp iii Temperature sensations 1 Conducted along the same pathways that carry pain sensations 2 Sent to a The reticular formation b The thalamus c The primary sensory cortex to a lesser extent c 3 Mechanoreceptors d 4 Chemoreceptors i Sensitive to stimuli that distort their plasma membranes ii Contain mechanically gated ion channels whose gates open or close in response to 1 Stretching 2 Compression 3 Twisting 4 Other distortions of the membrane vibrations i Respond only to water soluble and lipid soluble substances dissolved in surrounding fluid ii Receptors exhibit peripheral adaptation over period of seconds 1
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