BSC2086 Anatomy Physiology II Exam 1 You Should Be Able To Lesson 1 General Senses Describe the differences between the afferent and efferent divisions of the nervous The afferent division of the nervous system carries sensory information to the CNS Sensory pathways sensory neurons and their receptors The efferent division of the nervous system carries motor information commands away from the CNS to effectors muscles glands descending Nuclei motor tracts and motor neurons that control peripheral effectors Describe the types of stimuli that are detected by our general senses and special system ascending o Made up of o Made of up senses General Senses Temperature Pain Touch Pressure Vibration Proprioception Special Senses Olfaction smell Vision sight Gustation taste Equilibrium balance Hearing What is the difference between these two senses General senses describe our sensitivity to temperature pain touch pressure vibration o Sensory receptors distributed throughout the body relatively simple in structure Special senses are olfaction smell vision sight gustation taste equilibrium and proprioception balance and hearing o Sensory receptors located in sense organs are structurally complex Explain the difference between sensation and perception Sensation is the arriving information from these senses Perception is the conscious awareness of a sensation Explain why receptor specificity and the size of the receptive field are important in stimulus detection and localization Receptor Specificity The characteristic sensitivity of a receptor o The more specific the receptor the more specific the type of information it provides 1 BSC2086 Anatomy Physiology II Exam 1 You Should Be Able To May result from structure of receptor cell or the presence of accessory cells structures Complex receptors are more specific only respond to certain stimuli Ex Eyes usually only exposed to light provide very specific information Receptive Field The area monitored by a single receptor cell o The larger the receptive field the more difficult it is to localize a stimulus o Skin can only describe general area of stimulus light touch o Tongue can be very precise about location of a stimulus Explain how specific stimuli are relayed to the central nervous system what is labeled line Sensory information routed according to location nature of stimulus o Different sensations arrive at their corresponding regions of the cortex Ex Visual information to visual cortex Labeled Line The link between a peripheral receptor and cortical neuron o Each labeled line consists of axons carrying info about one modality type of o CNS interprets the modality entirely off of the labeled line Ex Rub your eyes see a flash of light because it arrives at the visual cortex is interpreted as a visual perception o Identity of active labeled line indicates the type of stimulus o Where the labeled line arrives within the sensory cortex determines its perceived stimulus location Ex Activity in a labeled line that carries touch sensations stimulates facial region of primary sensory cortex you perceive a touch on the face Describe adaptation and how it can affect our perception of a stimulus Adaptation A reduction in sensitivity in the presence of a constant stimulus o You gradually become less aware of a stimulus that is constant and painless o Incoming sensory information is then processed in centers along the spinal cord or brain stem at the subconscious level o Ex Clothes on your skin a temperature change What is the difference between central and peripheral adaptation Central Adaptation Adaptation that occurs along sensory pathways inside the CNS o Sensory neurons remain active o Generally involves inhibition of nuclei along a sensory pathway o Restricts the amount of detail that arrives at the cerebral cortex Peripheral Adaptation Adaptation that occurs when the level of receptor activity changes o Responds strongly at first but gradually declines 2 BSC2086 Anatomy Physiology II Exam 1 You Should Be Able To o Reduces the amount of information that reaches the CNS o Characteristic of phasic receptors fast adapting receptors Thermoreceptors Temperature receptors You rarely notice room temperature unless it changes suddenly Explain the difference between tonic and phasic receptors Tonic receptors are slow adapting receptors that are always active o Show little peripheral adaptation o Background level of stimulation Phasic receptors are fast adapting receptors that are normally inactive o Become active whenever change occurs o Provide info about the intensity rate of change of a stimulus Describe the three broad categories of sensory receptors Exteroceptors provide information about the external environment Proprioceptors report the positions of skeletal muscles and joints Interoceptors monitor visceral organs and functions Describe the four types of general sensory receptors What are some specific examples of these receptors and their function Nociceptors Pain receptors o Free nerve endings with large receptive fields o Can be stimulated by many different stimuli o Tonic receptors slow adapting o Three types based on what they re sensitive to Extremes of temperature Mechanical damage Dissolved chemicals o Function to make one aware of damage to the body seek medical treatment Thermoreceptors Temperature receptors o Free nerve endings located in the dermis skeletal muscles liver and o Phasic receptors very active when temperature is changing but quickly adapt to hypothalamus a stable temperature o Function to detect the temperature of our environment Mechanoreceptors Sensitive to stimuli that distort their plasma membranes o Contain mechanically gated ion channels Gates open or close in response to Stretching Compression Twisting Other distortions of membrane 3 BSC2086 Anatomy Physiology II Exam 1 You Should Be Able To o Three 3 classes Tactile receptors Baroreceptors Proprioceptors o Generally function to provide us information related to touch pressure and Source of stimulation shape size texture movement Changes in pressure in an organ Position of joints tension and state of muscular contraction Chemoreceptors Chemical receptors o Respond only to water soluble lipid soluble substances dissolved in bodily position fluids o Exhibit peripheral adaptation in seconds central adaption may occur o We are not consciously aware of the sensations they provide o Function to monitor pH and carbon dioxide and oxygen levels in arterial blood o Located in
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