Sensory System

• Vertebrate nervous system

  • Central ns: brain and spinal cord
  • Peripheral ns: nerves that connect CNS to receptors
• Sensory receptor cells - monitor changes in internal and external environment
• Lamprey (olfactory)

  • Single nostril
• Chondrichthyes (olfactory)

  • Septa to passage through nasal sacs
• Actinopterygii (olfactory)

  • Two naris and sensory plates
• Others (olfactory)

  • nose
• Gustatory receptors (taste)

  • On skin in some fish
  • Throughout pharynx and mouth in amphibians and reptiles
  • Tongues in mammals
• Red and cone cells

  • Visible electromagnetic radiation
• Scotopic system - rods, sensitive to dim light (not color)
• Photopic system - cones, color sensitive
• Tapetum lucidum - reflective layer behind retina for extra extraction of light
• Cataracts or glaucoma - blindness
• Pit organ cells

  • Loreal pit
  • Infrared thermoreceptors
• Mechanicals, temp, electrical receptors

  • Cutaneous receptors - detect mechanical changes to environment at surface, free nerves endings and associated nerves endings
  • Proprioceptors - located in muscles, tendons, joints: continuous sensory feed back to CNS
• Lateral line, ear, electroreceptors

  • Neuromast (w/ scales)
  • Inner ear is similar in structure in vertebrates
  • External acoustic meatus in squamates, tympanum in frogs
  • Mammals have more located inside canal than others/longer canal