7.4

• Specific deficit in hearing high frequencies.

  Age-related hearing loss
• ringing of ears

  Tinnitus
• bypass damage to the auditory hair cells by converting sounds picked up by a microphone on the patient’s ear to electrical signals, which are then carried into the cochlea by a bundle of electrodes. These signals excite the auditory nerve.

  Cochlear Implant
• True or False, although cochlear implants can provide major benefits, they do not restore normal hearing.

  True
• Sensations from your body.

  Somatosensations
• System that mediates these bodily sensations.

  somatosensory system
• Three Separate Systems of the Somatosensory System:


  exteroceptive system, proprioceptive system, interoceptive system
• Senses external stimuli that are applied to the skin.

  exteroceptive system
• Monitors information about the position of the body that comes from receptors in the muscles, joints, and organs of balance.

  proprioceptive system
• Provides general information about conditions within the body (e.g., temperature and blood pressure).

  interoceptive system
• three somewhat distinct divisions of the exteroceptive system:

  a division for perceiving mechanical stimuli (touch)

  one for thermal stimuli (temperature)

  one for nociceptive stimuli (pain)
• This is the simplest cutaneous receptors. Neuron endings with no specialized structures on them. Particularly sensitive to temperature change and pain.

  free nerve endings
• Onion-like largest and deepest cutaneous receptors that adapt rapidly, they respond to sudden displacements of the skin but not to constant pressure.

  Pacinian corpuscles
• respond to gradual skin indentation

  Merkel’s Disks
• respond to skin stretch

  Ruffini Endings
• Identifying objects by touch

  Streognosis
• Two Major Somatosensory Pathways

  dorsal-column medial-lemniscus system

  anterolateral system
• tends to carry information about touch and proprioception

  dorsal-column medial-lemniscus system
• tends to carry information about pain and temperature

  anterolateral system
• Lesions of the dorsal-column medial-lemniscus system do not eliminate touch perception or proprioception