lecture_notes_11_(ta)

lecture_notes_11_(ta) - Lecture 10: Sensory Systems II...

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Lecture 10: Sensory Systems II – Receptor Physiology Reading: same as Lecture 9 Somatosensory - somatosensory receptors are located in the skin, skeletal muscles, tendons and ligaments. They are subdivided into distinct categories (modalities) that provide for the sensations of touch (mechanoreceptors) (Figure 6-6) , pain (nociceptors) , temperature (thermoreceptors) , and proprioception (mechanoreceptors) , which signals muscle tension and limb position. Each of these categories is subdivided into separate submodalities to signal the full range of sensory stimuli. An example of this is the separate classes of receptor cells in the skin that signal light touch and pressure. Mechanoreceptors convert mechnical deformation of the skin into a receptor potential. Visual - visual receptors, referred to as photoreceptors , are specialized cells (not neurons) located on the outer surface of the retina (Figures 6-10,6-22,6-25,6-29) . They are composed of two classes of cells termed rods and cones (Figures 6-22,6- 25) . The rods are sensitive to low levels of light (scotopic vision). The cones are sensitive to higher levels of light (photopic vision) and composed of three subclasses that are sensitive to light of different wavelengths (Figure 6-27) . Photoreceptors contain specialized intracellular membranes, located in their outer segments, which can convert the absorption of light into a hyperpolarizing receptor potential. This in turn leads to a reduction in the amount of neurotransmitter released onto the retinal neurons. Major components of the eye – cornea, pupil lens, aqueous humor, vitreous humor, retina, choroid, sclera, optic disc (Figure 6-10) . THREE MAIN LAYERS TO THE EYE: -SCLERA (CONNECTIVE TISSUE, VISIBLE WHITE PORTION OF THE EYE) / CORNEA (TRANSPARENT WINDOW THROUGH WHICH LIGHT PASSES). - CHOROID (NOURISHES THE RETINA)
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lecture_notes_11_(ta) - Lecture 10: Sensory Systems II...

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