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2011-12-05 16:04:22
sensory physiology

sensory physiology
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  1. describe the criteria used for classifying sensory receptors by the origin of the stimulus:
    • exteroceptors: external, special senses, touch
    • interoceports: internal organs
    • proprioceptors: muscles, tendons, joints, that sense body position, movement
  2. differentiate between the general and special senses and give an exmple of each:
    • general senses
    • found all over the skin, muscles, and viscera
    • include touch, pressure, stretch, temp, pain

    • special senses
    • limited to the head, innervated by CNS
    • include vision, hearing, equilibrium, taste, smell
  3. identify the receports that are unencapsulated and the fxn of them:
    unencapsulated: dendrites that are not wrapped in connective tissue, very simple receptors

    • types of receptors
    • free (fine) nerve endings: pain, temperature
    • tactile discs: light touch (texture, edges, shapes) and pressure on skin (tonic, slow to adapt)
    • hair receptors: light touch that bends hair, hair movement, ( a bug walking on skin)
  4. -identify the receptors that are encapsulated and the fxn of them:
    encapsulated: nerve endings wrapped in glial type cells or connective tissues

    • types of receptors
    • tactile corpuscles: flattend out schwann cells, light touch, texture, phasic, found in the hairless skin areas such as hands and soles of feet
    • end bulbs: endings are thru bulbs of connective tissue, light touch, texture, phasic, found on tongue and lips
    • lamellar corpuscles: senseory dendrite travels thur the center of the corpuscle (inner myelin layer) deep pressure vibration, phasic, found in the joints, dermis, viscera
    • blubous corpuscles: ending are thru the corpuscle, heavey touch, pressure, stretch, found in the tendons and dermis
    • muscle spindles: within structures, stretch, propioceptors, tonic, muscle
    • tendon organ: ending within structures, tension on tendons, proprioceptors
  5. describe how pain is sensed by the nervous system:
    • pain: discomfort caused by injury or noxious stimulation, leading to evasive action
    • injured tissue release bradykinin (potent pain stimulus) and prostaglandins
    • these activate nociceptors and trigger pain

    • fast pain: via myelinated fibers at 12 to 30 m/s, sharp, localizated, stabbing pain
    • slow pain: via unmyelinated fibers, 0.5 to 2 m/s, long lasting, dull pain
  6. explain the concept of referred pain:
    • referred pain: results from the convergence of neural pathways in the CNS.
    • the brain cant ID the exact sourse and assumes the most likely one
    • pain in viscera is thought to come from somewhere else
    • Example: heart attact, pain is felt radiating from the left sholder and medial part of the arm
    • essential for diagonosis
  7. explain how modulation of pain works:
    • endogenous opioids: (internally produced opium-like substances) block the transmission of pain signals in the spinal cord, so you dont receive pain
    • examples: soliders wounded in battle, childbirth, runners high, or 2nd wind
  8. Outline the structures of the CNS that transmit and process general sensory information:
    • somatosensory signals from the head,travel by way of CN to the pons, madulla oblongata
    • first order neurons (corical pain recognition) synapse with 2nd order neurons
    • 2nd order neurons (spinothalamic) decussate, lead to contralateral thalamus
    • 3rd order neurons complete route to cerebellum
    • exception: proproceptive signals, 2nd order neuron carries signal to cerebellum
    • other tracts: limbic system (fear), hypothalmus (relaxation, nausea)
  9. Name the five primary taste sensations:
    • bitter: alkaloids, coffee, cacao, olives
    • sour: acids (acetic, citric)
    • salty
    • sweet: sugars, sucrose, maltose
    • umami/amino acids: beef, tomatos
  10. describe the chemical senseation of gustation (taste):
    chemicals stimulate taste buds, chemcials must be dissolved to be tasted
  11. Describe the anatomy of gustation (taste):
    • 4000 taste buds distrubuted on papillae (surface protrusions)
    • regrardless of location, all buds look the same
    • vallate papillae: 7-12 papillae, with about 250 taste buds each
    • filiform papillae: no taste buds, sense of texture of food, grooming in animals
    • fungiform papillae: 3 taste buds each, concentrated at the tip and sides of the tongue
  12. describe the physiology of gustation (taste):
    • CN VII collects sensory info from anterior 2/3rds of the tongue
    • CN IX collects from the posterior 1/3rd
    • CN X collects from taste buds, palate, pharynx, epiglottis

    • all taste fibers project into medulla oblongata
    • 2nd order neurons to the hypothalamus activate salivation, gaggin, vomiting
    • 3rd order neurons to the cerebrum where we are conscious of the taste
  13. describe the anatomy of olfaction:
    • olfactory mucosa: roof of the nasal cavity
    • olfactory bulbs (olfactory cells), basal cells replace olfactory cells every 60 days
    • olfactory cells are neurons, each cell has 350 kinds of receptors to bind to oderant molecules
    • cribiform plate has channels for olfactory bulbs
  14. describe the physiology of olfactotion:
    • odorant molecule binds to receptor
    • triggers action potiential at the axon of olfactory cell
    • signal is transmitted to the brain
  15. Name the crainal neres and structures that transmit and process gustatory sensory info:
    • crainal nerves
    • vii facial nerve: anterior 2/3rds
    • xi glossophraygneal nerve: posterior 1/3rd
    • x vagus nerve: palate, phyranx, epiglottis
  16. Name the crainal nerves and structures that transmit and process olfaction sensory information:
    • orbitofrontal cortex: flavor, intergration of taste and smell
    • olfactory tract: uniquness, tracts do not go thru hippocampus

    secondary distinations: smells can be remembered, evoke emotions so amgydal, is emotions, hippocampus is memory, hypothalmus is reflexes
  17. Identify the structures of the outer ear:
    • auricle
    • auditory canal
  18. identify the structures of the middle ear and explain their fxn:
    • tympanic membrane: vibrations in response to sound
    • ossicles: stapes (stirup), incus (anvil), malleus (hammer) vibrations are passed to the osscicles from tympanic membrane
  19. identify the structures of the inner ear and explain the fxn:
    • auditory (eustachian) tube: passage way to the throat, equalizes pressure on either side of ear drum (swallowing, yawn)
    • vestibule: equilibrium
    • cochlea: hearing
    • semicircular ducts: equilibrium
    • round window: equalizes fluid in cochlea
    • boney labyrinth: houses membranous labyrinth, "tube within a tube"
    • perilymph: fluid cushion between labyrinths (CSF)
    • endolymph: protection inside labyrinths (ICF)
  20. Describe the anatomy of the cochlea and explain how it contributes to hearing:
    • scala vestibuli: perilymph
    • scala tympani: perilymph
    • oval window --> scala vestibuli -->pressure pushes down --> scala tympani --> round window bends, releases pressure --> builds up pressure in estachian tube
  21. describe the structure of the vestibule, and semicircular canals
    • 2 chambers: saccule, utricle
    • 3 semicircular ducts
  22. describe static equilibrium:
    the preception of the head orientation when stationary
  23. describe dynamic equilibirum:
    • preception of motion and acceleration
    • liner acceleration: change in velocity in a straight line
    • angular acceleration: change in rate of rotation (porsche rounding a corner in a car)
  24. Explain the principle events involved inthe physiology of hearing and equalibrium:
    • otoliths: add weight and inertia, "little stones"
    • otholithic membrane: applies pressure to hair cells as changing orientation, acceleration
    • hair cells stimulate nerve endings
    • saccule and utricle movement: detect change in position
    • saccule only: verticle acceleration/decceleration
    • utricle only: horizontal acceleration/deccerleration
    • anterior/posterior semicircular ducts: verticle, right angels to each other
    • lateral semicircular ducts: 30 degrees off of horizontal
    • endolymph lags behind due to inertia
    • (semicircular ducts, like spinning in a chair)
  25. Name the crainal nerves ans sstructures of the CNS involved in the transmission and processing of hearing and equalibirum:
    • structures
    • vestibular cortex to the vestibular nucli: awarness of spatial orientation and movement
    • pons: keeps eyes fixated on target, compensatory eye movement
    • cerebellum: motor coordination
    • spinal cord: helps maintain balance, postural reflexs

    • CN
    • iii ocloumotor
    • iv trochlear
    • xi abducens
  26. Identify the accessory structures of the eye, including the extrinsic eye muscles and discuss their fxn:
    • eyebrows, eyelids, eyelashes: eye protection
    • conjunctiva: transparent mucose membrane, covers anterior eye except cornea, highly vascular, prevents eyes from drying out
    • lacrimal apparatus: lacrimal gland, lacrimal canal, lacrimal sac, nasopharyngeal duct, drain tears into the nasal cavity
    • tears: cleanse and lubricate, deliver oxygen and nurtirents to conjunctiva, prevent infections

    • Extrinsic eye muscles/innervation
    • superior oblique: trochlear nerve
    • lateral rectus: abducens
    • superior, medial, inferior rectus, and inferior oblique muscle: oculomotor
  27. describe the tunica fibrosa layer of the eye including its structures and fxn:
    • fibrous outer layer
    • sclera: "whites of the eyes", dense connective tissue
    • cornea: transparent sclera, admits light and refracts light
  28. describe the tunica vasculosa layer of the eye, including its structures and fxn:
    • vascular layer
    • choroid: highly vascularized and heavily pigmented
    • ciliary body: musclar rign around the lens and secretes aqueous humor
    • iris: controls pupil diameter, contains chromatopores(contains melanin for color)
  29. describe the tunica interna layer of the eye and include is structures and fxn:
    • inner neural layer
    • retina: photoreceptors
    • optic disc: blind spot, no receptors present, never, blood vessels enter/exit
    • optic nerve:
  30. describe vitrious humor:
    gel, maintains eyeball shape, keeps retina in place
  31. describe what cataracts are and how they affect the eye:
    • cloudiness of the eye
    • can replace lens with plastic lens
  32. describe what glaucoma is and how it affects the eye:
    • pressure inside as aqueous humor is not reabsorbed fast enough
    • aqueous humor -->pressure on lens --> vitrous body --> pressure on retina and compresses blood supply --> retina cell damage and optic nerve atropy
  33. Explain refraction image formation
    • refraction: when light rays bend upon striking at an angle
    • no refraction at cornea when straight on, cornea bends light rays the most, the lens fine tunes image
  34. explain accomidation image formation:
    • accomidation: change in lens curvature to focus on near objects
    • ciliary muscles contract, loosening the suspensatory liagments and relaxing the lens to thicken up
    • more convex lens refract light more to focus rays on retina
  35. explain the actions that change the size of the pupil:
    • a. distance ojbect already in focus: ciliary bodies are relaxed, sepensory ligaments are taut, lens is flattend
    • b. near object out of focus: cilary muscles are relaxed
    • c. near object in focus: firing of PSNS nerves, contract (tighten) ciliary bodies, and slacken sepensatory ligaments, and the lens is rounded and thick
  36. describe hyperopia (farsightedness) including where the image comes into focus relative to the retina under these conditions:
    • eyeball is too short
    • focal plane behind the retina
    • convex lens converges light rays
  37. describe myopia (nearsightedness) including where the image comes into focus relative to the retina under these conditions:
    • eyeball is too long
    • focal plane is in front of the retina
    • concave lens diverges rays
  38. describe the retina:
    • pressed against the choroid by vitrous humor
    • needs oxygen and nutirtens from choroid
    • fovea centrails: image focus, large # of cones
    • optic disc: blind spot
  39. a darkly pigmented layer, the most posterior part of the retina, that serves to absorb lights so that it doesnt degrade the visual image is called:
    pigment epithelium
  40. describe the the structure and fxn of rods photoreceptors:
    photoreceptors: cells that absorb light and generate a chemical or electricle signal

    • outer segment of rods: cylinrical, neatly arrayed stacked 1000 membranous discs, each disc is gobular proteins called rhodopisn
    • inner segment of rods: mitochondria, and other organelles
    • base of rods: cell body

    fxn: membranes hold pigment molecules in a postition that results in the most efficient light absorption, and produce images in only shades of grey
  41. describe the structure and fxn of cone photoreceptors:
    photoreceptors: cells that absorb light and genereate a chemical or electrical signal

    • outer segement of cones: tapers to a poin, discs are paraelle infoldings of the plama membrane
    • inner segement of cones: mitochrindria, and other organelles
    • base: cell body w/ nucelus

    fxn: day vision, and color vision
  42. describe the characteristics of rod photoreceptors:
    • 130 million
    • concentrated at retina periphery
    • low vision light
    • highly senstive
    • low/no color - shades of grey
    • low resolutins
  43. describe the characteristics of cone photoreceptors:
    • 6.5 million
    • concentrated at retina center (fovea cnetral)
    • day vision light
    • lower sensitivity
    • color discernment
    • fine resolution
  44. trace the signaling pathway for vision including cell types and CNS structures that tansmit and process visual information
    • Structures
    • opsin: a major part of rhodopsin, protein
    • retinal: a major part of rhodopsin, a vitamin A deriveative
    • cis- retinal: an isomere present in the absencse of light
    • trans-retinal: "bleached", isomere produced in the presense of light

    • pathway
    • 1. (in the dark) rhodopsin (cis-retinal) absorbs photon of light
    • 2. (in the light)cis-retinal isomerizes to trasn-retinal
    • 3. opsin triggers a rxn, cessation of dark current, signals created in optic nerve
    • 4. trans-retinal separates from opsin
    • 5. ( in the dark again) trans-retinal is enzmatically converted back to cis-retinal
    • 6. opsin and cis-retinal enzymatically combind to regenerate rhodopsin
  45. describe how vision would be affected if the visual pathway was severed at the optic nerve:
  46. Which of the following receptors are found only in the eyes?

  47. The position and movement of the body is sensed by __________ and can be found in _________.

    chemoreceptors; inner ear
    proprioceptors; muscles and tendons
    phasic receptors; inner ear
    nociceptors; muscles and tendons
    exteroceptors; eye
    proprioceptors; muscles and tendons
  48. Which of the following is NOT a modality of unencapsulated nerve endings?

    movement of hairs
    light touch
  49. Which of the following is not a taste sensation?

    all of the above are taste sensation
  50. Which of the following is NOT an encapsulated nerve ending?

    tactile disc
    bulbous corpuscle
    lamellar corpuscle
    tactile corpuscle
    tactile disc
  51. What type of receptors are involved in olfaction?

  52. Based upon proportionality in Figure 14.22, which of the following body regions should have the finest two-point touch discrimination?

  53. After a period of wearing your shirt, you become unaware that you are wearing one; the constant touch of the material on your skin is no longer continually apparent. Which type of receptors is responsible for this phenomenon?

    tonic receptors
    phasic receptors
    phasic receptors
  54. Put the following events in the transmission and modulation of pain signals in the correct order.

    midbrain relays signals to medualla oblongata
    nociceptors stimulates 2nd order nerve
    enkephalins inhibit 2nd order nerve
    3rd order neuron relays signal to somesthetic cortex
    • nociceptors stimulates 2nd order nerve
    • 3rd order neuron relays signal to somesthetic cortex
    • midbrain relays signals to medualla oblongata
    • enkephalins inhibit 2nd order nerve