aniphys CH7:sensing enivroment

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  1. % of animal species with image-forming eyes
  2. category of sensation; touch, light, sound
  3. features that characterize stimuli within a particular modality
  4. neuron whose axon carries the signal to the central nervous system is called
    primary afferent neuron
  5. process by which receptor cells change stimulus energy into the energy of a nerve impulse
  6. weakest stimulus that will produce a response in a receptor 50% of the time
    threshold of detection
  7. general process of sensory receptors
    detection-amplification-encoding and discrimination-adaptation-gating of ion channels-electrical response of membrane-transmission to brain
  8. senses muscle length
    stretch receptors
  9. TTX
    block volt gated Na+ channels eliminating APs
  10. produces APs during only part of the stimulation
    phasic recptor
  11. fires APs throughout the duration of stimultation
    tonic reptors
  12. when  the recptor potential spreads to the spike-initiating zone and directly modulates the generation of APs
    generator potential
  13. stimuli encoded only over a limited range of intensity
    dynamic range
  14. amplitude of receptor potentials is approx proportional to
    logarithm of the stimulus intensity
  15. prolonged exposure to stimulus causes change in amplification of receptor events, alters way it encodes
    sensory adaptation
  16. individual receptors or sensory afferents cover only a fraction of the total dynamic range of the sensory system
    range fractionation
  17. more sensitive to light and respond to dimmer stimuli
    rod photoreceptors
  18. respond to bright light that saturates rods
    cone photoreceptors
  19. pacinian corpuscle
    vibration, pressure receptor
  20. where does sensory adaptation take place
    • 1. by receptor cells as filters.
    • 2 receptor cells may run down. pigment bleached
    • 3.enzyme cascade activated by receptor may be inhibited.
    • 4. electrical properties of receptors change during sustained
    • 5.membrane of spike initiating zone become less excitable
    • 6.takes place in higher order cells in the CNS
  21. responds to dissolved molecules
    gustatory receptors (taste)
  22. respond to airborne molecules
    olfactory receptors (smell)
  23. response to H+
  24. for salts, cells responds to positive ions only
  25. G protein dependent mechanisms of taste modalities
    bitter and sweet
  26. complex nasal cavities in olfactory dependent animals
  27. nasal olfactory transduction cascade:
    enzyme, adenulate cyclase, that when activated by G protein catalyzes and increase in intracellular cAMP
  28. how mechanorecptors stimulus activated:
    stretch or distortion of its plasma membrane
  29. area of the eardrum
    approx 0.6 cm^2
  30. area of oval window
    0.032 cm^2
  31. frequency in which a cell responds moststrongly
    electrical resonance frequency
  32. transduce photons of light into electrical signals
  33. light absorbing organic molecule
  34. bent light
  35. in compound eyes optic unit is called
  36. ommatidium take in about:
    2-3 degrees of visual field
  37. vertebrate eye receptor take in
    0.02 degree of the visual field
  38. part of the reticular cell where the plasma membrane is thrown into densely packed microvilli.
  39. incident light rays are refracted when passed through the clear outer surface of the eye
  40. once passed through the cornea and lens the inverted image on the rear internal surface of the eye
  41. distance at which an image passed through the lens comes into focus
    focal length
  42. lens is held in place by the radially oriented
    zonular fibers
  43. contraction of ciliary muscles to shape lens
    accomodation. pulls choroid forward allows natural contraction
  44. farsightedness
  45. left and right eyes are positioned by the ocular muscles so that the images fall on analogous parts of the two retinas
    binocular convergence
  46. visual pigments in which 3-dehydroretinal is the light absorbing molecule
  47. activated rhodospin activates a G protein
  48. nutritional deficiency of vitamin A
    decreases the amount of retinal that can be synthesized and hence decreases the amount of rhodopsin. ie. night blindness
  49. releases transmitter continuosly in the dark
    vertebrate visual receptor
  50. protein component of visual pigments
  51. parallel light rays form distnt object focused on retina with ciliary muscles relaxed. clear vision with relaxed muscles
  52. parallel light rays focus behind reina. diffuclty seeing close
  53. parallel light rays focussed in front of retina. cant focus distant objects
  54. refractive eror due to cornea or lens shape
  55. rods
    • 125 million
    • long,thin diameter 2-3 mm
    • can change length
    • very few in foxea centralis
    • increase in density tword periphery
    • specialize in low intensiy illumniation
    • twilight and night vision
  56. cones
    • 5.5 millio
    • shor, fat diamter 4-10 um
    • used for high intensity, clear
    • color determination 3 pigments rgb
    • several phptochemicals similar to rhodospin
    • different spectral sensitvity
Card Set:
aniphys CH7:sensing enivroment
2013-10-29 10:11:47
animal physiology ekert sensing enviroment

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