Special Senses

• Sclera


  Outer layer, white part, helps maintain shape of eye & protects it
• Choroid


  Middle layer, contains blood vessels
• Retina


  Inner layer, light rays focus an image on it
• Rods


  Sensitive to dim light
• Cones


  Sensitive to bright light and color
• Optic disc


  Nerves gather together here to form optic nerve, known as blind spot
• Cornea


  Clear part in front of iris, clear so that light rays can pass through
• Iris


  Colored part of eye, muscular
• Lens


  Structure located behind iris and pupil, elastic and disk shaped
• Optic nerve


  Image travels to cerebral cortex via this
• The process of seeing

  1. Light hits retina

  2. Photoreceptors turn light into signals

  3. Signals travel to optic nerve

  4. Optic nerve sends signals to the brain
• Structures/Functions of the Ear

  • Outer ear
  • Middle ear
  • Inner ear
• Pinna (auricle)


  Outer ear, collects sounds waves
• Auditory canal


  Ear canal
• Tympanic membrane


  Eardrum, separates outer and middle ear
• Malleus, incus, stapes


  Bones in middle ear transmit sound waves from eardrum to inner ear
• Eustachian tube


  Equalizes pressure in middle ear
• Cochlea


  Spiral shaped organ of hearing
• Semicircular canals


  3 structures of inner ear, help maintain body balance
• The pathway of hearing

  1. Sound

  2. Auricle

  3. Auditory canal

  4. Middle ear bones

  5. Cochlea

  6. Vestibulocochlear nerve

  7. Brain
• Structures/Functions of Nose

  • Nasal cavity
  • Cilia
  • Septum
  • Olfactory bulb
• Nasal cavity


  Humidify and warm the inspired air
• Cilia


  Respiratory defense
• Septum


  Helps with airflow
• Olfactory bulb


  Receives info about smells and sends it to the brain
• Structures/Functions of the Tongue

  • Papilla
  • Taste buds
• Papilla


  Help grip food while chewing
• Taste buds


  Allow you to taste