Sensory System

• General senses


  Widely distributed throughout the body
• General senses


  • Include tactile receptors in skin, joints and muscles
• Special senses


  Located in the head
• Special senses


  • Gustation (taste)
  • Olfaction (smell)
  • Vision (seeing)
  • Audition (hearing)
• Receptive field


  Area a receptor can detect stimuli
• Range of the receptor


  Not all receptors have the same range
• Smaller the receptive field

  The more sensitive and precise the receptor
• Some areas of the body have more receptors with smaller fields (palms, fingers, face)
• Some areas of the body have fewer receptors with bigger receptive fields to cover the distance (trunk, arms, legs etc)
• Areas with more receptors


  Have more sensory cortex devoted to it
• Cutaneous receptors


  Sensory receptors in the skin
• Types of cutaneous receptors

  • Mechanoreceptors
  • Nociceptors
  • Thermoreceptors
• Mechanoreceptors


  Detect physical movements, vibrations
• Nociceptors


  Detect pain as well as tissue damage not only on the surface (SOMATIC) but within the body (VISCERAL)
• Nociceptors


  Respond only to Noxious stimuli and generate nerve impulses which the brain interprets as "Pain"
• Thermoreceptors


  Detect temperature ranges
• Thermoreceptors are widely distributed
• Baroreceptors


  Detect changes in pressure
• Baroreceptors are found in carotid arteries
• Photoreceptors


  Detect light, color and movement
• Photoreceptors are in the retina of the eye
• Proprioceptors


  Relay info on limb position
• Proprioceptors are found in joints and ligaments
• Rods


  Live mostly around the edge of the retina
• Cones


  Are concentrated right in the center of the retina
• The location of taste receptors is in the oral cavity, with the valiate being in the back, filiform being around the center, and fungiform being around the edges (front).
• The location of olfactory receptors is through the Cribiform plate of the ethmoid bone, olfactory bulb, olfactory tract (to cerebral cortex, and fibers of olfactory nerves.
• The auditory ossicles are the malleus, incus and stapes
• Disarticulation or fusing of the auditory ossicles can lead to conduction deafness
• Ring of Muscle


  Controls Shape and accomodation of eye
• Pupil

  Hole in iris that let's light in
• Cornea


  Thick layer of transparent cells that protect eye and are principle means of focus rays by refraction entering eye.
• Iris

  Colored ring of Muscle Controls pupil size
• Jelly lens

  Fine focus rays on retina by accommodation
• Retina

  Layer of light sensitive cells (rods and cones) change light into electrical signals.
• Optic nerve


  Carried electrical impulses in brain for image information processing.
• In Gustation, taste buds are wrapped in

  Taste stratified squamous epithelium, resting above lamina propria, and houses neuroepithelium/supporting cells. Trench is on top.