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Receptors

Receptors. Receptors. Sensory receptors – specialized cells or cell process that monitors conditions in the body or the external environment Sensory information goes to the CNS and is called a SENSATION Conscious awareness of sensation is PERCEPTION. General Senses. Temperature Pain Touch

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Receptors

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  1. Receptors

  2. Receptors • Sensory receptors – specialized cells or cell process that monitors conditions in the body or the external environment • Sensory information goes to the CNS and is called a SENSATION • Conscious awareness of sensation is PERCEPTION

  3. General Senses • Temperature • Pain • Touch • Pressure • Vibration • Proprioception (body position)

  4. Special Senses • Smell • Taste • Balance • Hearing • Vision

  5. Receptor Sensitivity • Receptors are sensitive to specific stimuli • Called receptor specificity • Simplest receptors are dendrites of sensory neurons • Free nerve endings • Receptive field • Larger the field the poorer the ability to localize a stimulus

  6. Sensory Processing • Sensory information must be sent to the CNS for processing • Arriving information is processed and interpreted by the CNS at both conscious and subconscious levels

  7. Sensory Limitations • We do not have receptors for every possible stimulus • Receptors have characteristic ranges of sensitivity • CNS must interpret the stimulus. Our perception of the stimulus is also an interpretation and not always a reality

  8. General Senses • Receptors for general senses are scattered through out the body • EXTEROCEPTORS – external environment • INTEROCEPTORS – conditions inside the body

  9. Nature of Stimulus • 1. Nociceptor • 2. Thermoreceptors • 3. Mechanoreceptors • 4. Chemoreceptors

  10. Nociceptors • Pain receptors • Superficial skin, joint capsules, bone, around walls of blood vessels • Free nerve endings, large receptive fields • Exact location pf painful sensation is often difficult to determine • Three types of nociceptors • Extremes of temperature • Mechanical damage • Dissolved chemicals from damaged cells

  11. Pain – Fast and Slow • Fast pain(prickling pain) – deeps cuts • Reach CNS very quickly – primary sensory cortex • Receives conscious attention • Painful sensations stop only after the tissue damage has ended • Slow pain(burning and aching pain) – similar injuries as fast pain • Sensation begins later and lasts longer • Aware of the pain but have only a general idea of the area affected

  12. Thermoreceptors • Found in the dermis, skeletal muscle, liver, and hypothalamus • Free nerve endings • Cold receptors are 3-4 times more numerous than warm receptors • Temperature sensations carried along same pathways as pain sensation • Thermoreceptors quickly adapt to stable temperature, very active when temperature is changing

  13. Mechanoreceptors • Sensitive to stretch, compression, twisting. • Three classes of mechanoreceptors • Tactile receptors • Baroreceptors(pressure changes in walls of blood vessels, urinary, digestive and reproductive systems) • Proprioceptors(monitor the position of joints and muscles)

  14. Tactile Receptors • Fine touch and pressure • Receptors may be free nerve endings or encapsulated • Encapsulated receptor examples are: • Tactile (Meissner’s) corpuscles for fine touch • Lamellated (Pacinian) corpuscles for heavy pressure

  15. Encapsulated receptors

  16. Baroreceptors • Stretch receptors that monitor changes in pressure • Found in walls of blood vessels, and respiratory, digestive, and urinary organs • Monitor blood pressure, help regulate cardiac function and blood flow • Monitor degree of lung expansion • Monitor visceral reflexes such as urination

  17. Baroreceptors

  18. Proprioceptors • Monitor position of joints, the tension on tendons and ligaments, and the state of muscle contraction

  19. Chemoreceptors • Specialized neurons that detect changes in the concentration of specific chemical or compounds • Changes in pH or carbon dioxide are monitored

  20. Chemoreceptors

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