Exam 1 Study GuideBSC2085 – Anatomy & Physiology 2Lesson 11. What is the difference between the afferent division and the efferent division of the nervous system? Which involves the sensory pathway? Which involves the motor pathway? What are their components?• Afferent Division: o Receptors (detects the stimuli) Specialized cells that monitor specific conditions in the body or external environment When stimulated, a receptor passes information to the CNS in the form of action potentials along the axon of a sensory neuron o Sensory neurons (relays the information down their axons)o Sensory pathways (nerves, nuclei, and tracts that deliver sensory information to the CNS) Deliver somatic and visceral sensory information to their final destinations inside the CNS using: Nerves (axon bundles in the PNS) Nuclei (cell bodies located in the CNS) Tracts (axon bundles in the CNS)• Efferent Division: Controls peripheral effectors, motor neurons and pathways that control skeletal muscles.o Nuclei (contains the cell bodies of motor neurons) o Motor tracts and nerves (carries commands to effectors – muscles and glands) Travel from motor centers in the brain along somatic motor pathways of: Motor nuclei, tracts (axons in the CNS – central nervous system), nerves (axons in the PNS – peripheral nervous system)2. What are the 6 general senses? What are the five special senses? Why is receptor specificity important to the detection of a specific stimulus. What does that have to do with labeled lines in the nervous system?• General Senses o Temperatureo Paino Toucho Pressureo Vibrationo Proprioception – monitors the position and movements of skeletal muscles and joints• Special Senses- Are provided by special sensory receptors located in sense organs such as the eye or ear are protected by surrounding tissueso Olfaction (smell)o Vision (sight)o Gustation (taste)o Equilibrium (balance)o Hearing • Receptor specificity o Each receptor has a characteristic sensitivity (your hands do not smell nor taste, your eyes do not hear, etc.)• Receptive field o Area is monitored by a single receptor cello The larger the receptive field, the more difficult it is to localize a stimulus• Labeled Lineso Arriving stimulus reaches cortical neurons via labeled line (link between receptor and cortical neuron) o Each labeled line carries info about one form (which involves specificity!) Physical force (such as pressure) Dissolved chemical Sound Light3. What is the difference between sensation and perception? If a receptor has a large receptive field, is it easier or harder to localize a stimulus? What if the receptor has a small receptive field?• Sensation: Taste, hearing, equilibrium, and vision provided by specialized receptor cells; The arriving information from these senses• Perception: Conscious awareness of a sensationo Your perception of the nature of that stimulus depends on the path it takes inside the CNS• The larger the receptive field, the more difficult it is to localize a stimulus, therefore, the smaller the receptive field, the easier it is to localize a stimulus (fingertips, lips, etc). 4. What is adaptation and how are tonic and phasic receptors involved? What is the difference between central adaptation and peripheral adaptation?• Adaptationo Reduction in sensitivity of a constant stimuluso Your nervous system quickly adapts to stimuli that are painless and constanto Ex. New smells, rings, earrings• Tonic Receptorso Are always activeo Show little peripheral adaptationo Are slow-adapting receptors Ex. Pain receptors (nociceptors) remind you of an injury long after the initial damage has occurred• Phasic Receptorso Are normally inactiveo Become active for a short time whenever a change occurso Are fast-adapting receptorso Provide information about the intensity and rate of change of a stimulus Ex. Thermoreceptors detect rapid changes in temp• Central Adaptation (book definition)o Adaptation also occurs along sensory pathways inside the CNS. For example, a few seconds after you have been exposed to a new smell, awareness of the stimulus virtually disappears, although the sensory neurons are still quite active. This process is known as central adaptation. Central adaptation generally involves the inhibition of nuclei along a sensory pathway.• Peripheral Adaptation (book definition)o Peripheral adaptation reduces the amount of information that reaches the CNS. Central adaptation at the subconscious level further restricts the amount of detail that arrives at the cerebral cortex. Most of the incoming sensory information is processed in centers along the spinal cord or brain stem at the subconscious level. Although this processing can produce reflexive motor responses, we are seldom consciously aware of either the stimuli or the responses.5. What are the four types of sensory receptors? What is the difference between the pain information sent by type A fibers and type C fibers?• Sensory Receptorso Nociceptors (pain receptor; common) In the superficial portions of the skin In joint capsules Within the periostea of bones Around the walls of blood vessels• Analgesia – inability to feel pain• Hyperalgesia – increased sensitivity to pain Sensitive to• Temperature extremes • Mechanical damage • Dissolved chemicals, such as chemicals released by injured cells Are free nerve endings with• Large receptive fields• Branching tips of dendrites • Not protected by accessory structures • Can be stimulated by many different stimulio Thermoreceptors (temperature receptor) Are free nerve endings located in:• The dermis• Skeletal muscles• The liver• The hypothalamus Temperature sensations Conducted along the same pathways that carry pain sensations sent to:• The reticular formation• The thalamus• The primary sensory cortex (to a lesser extent)o Mechanoreceptors (physical distortion) Sensitive to stimuli that distort their plasma membranes Contain mechanically-gated ion channels whose gates open or close in response to:• Stretching• Compression• Twisting• Other distortions of the membraneo• Baroreceptors o Detect pressure changes in the walls of blood vessels and in portions of the digestive, reproductive, and urinary tracts• Proprioceptors o Monitor the positions of joints and muscleso The most structurally and functionally complex of general sensory
View Full Document
Unlocking...