Bio 30 - Ch 12 The Senses

• What is a sensation?

  • activation of the neurons
  • action potential
• What is perception?

  • interpretation in the brain
  • processing in the CNS
• What is the sclera?

  • outer protective layer of eye
  • maintains shape
• What is the choroid?

  • full of blood vessels for nourishment
  • contains melanin (stops light from scattering)
• What are the suspensory ligaments?

  • connect ciliary body with lens
  • holds in place
  • controls shape of lens
• What is the iris (ring of muscle)?

  • changes size of pupil
  • controls amount of light entering
• What is the pupil?

  • opening for light to enter inner eye
• What are the lens?

  • behind iris
  • changes shape to focus image on retina
  • focuses light rays onto fovea centralis
• What is the cornea?

  • clear front of eye
  • "window"
  • bends light rays into eye
• What is the aqueous humor?

  • water like
  • keeps dome shape
• What is the ciliary muscle?

  • changes shape of lens in order to focus
• What is the vitreous humor?

  • jelly like
  • holds retina in place
• What is the retina?

  • inner layer
  • has photoreceptors (rods & cones)
• What is the fovea centralis?

  • contains high density of cones
  • provides acute vision
• What is the optic disc?

  • ganglion cells merge to form optic nerve
  • incapable of detecting light
• What is the optic nerve?

  • carries electrochemical impulses from eye to occipital lobe
• What are rods?

  • light/dark
  • contain rhodopsin
  • lights go out, rhodopsin gets regenerated
  • low threshold = easier to activate
  • found mostly in peripheral area
• What is rhodopsin?

  • inhibitory pigment that breaks down when exposed to light
• What are cones?

  • colour
  • contain photopsin
  • see other colours = different degree of signals going to brain
  • sensation (blue, green, red) = activated
  • higher threshold = harder to activate
• What is photopsin?

  • inhibitory pigment that breaks down in response to different wavelengths
• What is optic chiasm?

  • criss cross info to get to correct side
• What is the pinna?

  • redirect vibrations to auditory canal
• What is the auditory canal?

  • leads to eardrum
  • amplifies sound waves
  • making them louder
• What is the tympanum?

  • vibrates in response to sound waves
• What are the ossicles?

  • vibration magnifiers
  • transmits sound waves from eardrum to inner ear
• What is the eustacian tube?

  • extends from middle ear to throat
  • equalize air pressure from both sides
• What is the cochlea?

  • hearing receptors
  • mechanical energy of sound converts to electrochemical impulses that transmits to brainstem
• What is the oval window?

  • recieves vibrations from stapes
• What is the semicircular canal?

  • contains mechanoreceptors that detects rotational equilibrium
• What is the auditory nerve?

  • bending of the stereocilia
  • message relayed to nerve then sends an impulse to the temporal lobe
• What structures make up the auditory pathway?

  • pinna
  • auditory canal
  • tympanum
  • ossicles
  • oval window
  • cochlea
  • organ of corti
  • auditory nerve
  • temporal lobe
• What happens to the oval window when it vibrates?

  • creates movement in the fluid in the inner ear
• What is the organ of corti?

  • site where vibration is translated into a sensation (action potential)
• What is the tectorial membrane?

  • where the ends of stereocilia are embedded in
  • stimulates hair cells
• What is the basilar membrane?

  • has hair cells which produce stereocilia
  • supports hair cells
  • spreads sound vibrations that allow brain to interpret sound
• What causes the membrane to move?

  • vibrations in fluid
• What does the movement of hairs do to he nerve endings?

  • depolarizes it, which can result in action potential
• Where do semicircular canals send signals to?

  • the cerebellum
• What happens when you move or rotate in any dimension?

  • fluid moves in your canals
• What happens to the fluid moving?

  • pushes against hairs in the canal