Ch15NotesSum11

Ch15NotesSum11 - Ch. 15 Neural Integration I: Sensory...

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1 Fig. 15-1, p. 507 Ch. 15 – Neural Integration I: Sensory Pathways and the Somatic Nervous System Pathways = nerves, nuclei, and tracts that link the processing centers of the CNS with the rest of the body • Discussed in Ch. 15 : –1 . Sensory pathways • Both somatic sensory pathways and visceral sensory pathways –2 . Motor pathways •O n l y somatic motor pathways of the SNS are discussed in Ch. 15 Visceral
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2 Sensation and receptors Sensory receptors = specialized cells or cell processes that detect stimuli about conditions inside or outside of the body, and send that info to the CNS – The job of a receptor is transduction = the translation of a stimulus into action potentials (the “language” of the NS) Sensation = the info arrives in the CNS –Vs . perception = you are consciously aware of the sensation (only ~ 1% of sensations are perceived!) • No transduction no sensation • Senses : General senses : touch, pressure, vibration, temperature, pain, and proprioception • Receptors for the general senses are distributed throughout the body and are relatively simple in structure Special senses (Ch. 17): olfaction (smell), vision (sight), gustation (taste), equilibrium (balance), and hearing • Receptors for the special senses are found in special sense organs and are more complex in structure Receptor specificity Receptor specificity = (modality specificity) = receptors are specialized to detect different types of stimuli (modalities), e.g. light, sound, pressure, etc. – E.g. you can’t see with your ears – Receptor specificity results from the specific structure of the receptor cell and/or the presence of accessory structures – Receptor specificity examples : •1 . Pain receptors are free nerve endings (= the dendrites of sensory neurons) that respond to tissue damage from pressure, chemicals, heat, etc. – I.e. they have a simple structure, and are somewhat non-specific •2 . Photoreceptors in the eye have complex receptor cells, surrounded by a specialized pigment and CT layers, that respond
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3 Fig. 15-2, p. 508 Receptive fields Receptive field = the area monitored by a single receptor cell Smaller receptive fields more precise localization of the stimulus (e.g. the fingertips) Larger receptive fields less precise localization of the stimulus (e.g. the back) Transduction Guyton and Hall, 1996 • A stimulus causes a change in the membrane potential of a receptor – The change = a graded potential called a receptor potential – The stronger the stimulus the larger the change – The stimulus can cause depolarization (if it is excitatory) or hyperpolarization (if it is inhibitory) • A depolarizing receptor potential can also be called a generator potential The greater the generator potential, the more frequently action potentials are
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This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

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Ch15NotesSum11 - Ch. 15 Neural Integration I: Sensory...

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