Our Five Senses Systems

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Our Five Senses Systems

• Vision
• Hearing
• Taste
• Smell
• Touch

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Properties of Sensory Systems

• Stimulus
• Internal
• External
• Receptors
• Sense organs - structures
• specialized to respond to stimuli
• Conduction
• Afferent pathway
• Nerve impulses to the CNS
• Translation
• CNS integration and information processing
• Sensation and perception your reality

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Different Types of Receptors

• Mechanoreceptors respond to touch, pressure,
  vibration, stretch, and itch
• Thermoreceptors sensitive to changes in
  temperature
• Photoreceptors respond to light energy (e.g.,
  retina)
• Chemoreceptors respond to chemicals (e.g.,
  smell, taste, changes in blood chemistry)
• Pain Receptors sensitive to pain-causing stimuli

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Anatomy of the Eyeball

• Function of the eyeball
• Protect and support the photoreceptors
• Gather, focus, and process light into precise
  images

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The Inner Layer (Retina)

• Retina is the innermost layer of the eye lining
  the posterior cavity
• It contains the photoreceptors cones and rods

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Photoreceptors

• Two main types
• Rod cells
• More sensitive to light
• Allow vision in dim light
• In periphery
• Cone cells
• Operate best in bright light
• High-acuity
• Color vision blue, green, red cones
• Concentrated in fovea

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The Ear Hearing and Equilibrium

• The ear receptor organ for hearing and
  equilibrium
• Composed of three main regions
• Outer ear functions in hearing
• Middle ear functions in hearing
• Inner ear functions in both hearing and
  equilibrium

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The Outer (External) Ear

• The air inside your ear canal vibrates which
  causes the ear drum to also vibrate
• The ear drum forms the boundary between the
  external and middle ear

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The Middle Ear

• Contain the ear ossicles smallest bones in the
  body
• Malleus
• Incus
• Stapes
• Attach to the eardrum which vibrates as
  soundwaves come through the ear

Figure 16.17
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The Inner (Internal) Ear

• Inner ear a cavity consisting of three parts
• Semicircular canals
• Vestibule
• Cochlea
• The inner ear cavity is filled with fluid
  vibrations produce pressure waves in this fluid
• The sound receptors (mechanoreceptors) are minute
  hair cells located inside the cochlea

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The Chemical Senses Taste and Smell

• Taste gustation
• Smell olfaction
• Receptors classified as chemoreceptors
• Respond to chemicals

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Taste Gustation

• Taste receptors
• Occur in taste buds
• Most are found on the surface of the tongue
• Located within tongue papillae

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Taste Buds

• Collection of 50 100 epithelial cells
• Contain long microvilli extend through a taste
  pore
• Four basic qualities of taste
• Sweet, sour, salty, and bitter
• A fifth taste umami, deliciousness
• No structural difference among taste buds

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Smell (Olfaction)

• The lining of the nose has olfactory receptors,
  (chemoreceptors)
• Nasal surfaces are coated with secretions from
  olfactory glands
• Olfactory reception involves detecting dissolved
  chemicals as they interact with odorant-binding
  proteins

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Touch

• The skin contains many different types of
  receptors
• Pain receptors detect whether objects are sharp
  or dangerous
• There are hot and cold thermoreceptors
• There are also mechanoreceptors that detect
  pressure and movement on your skin

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