Lecture 10: Olfaction and Gustation

• What do sensory systems for gustation and olfaction respond to?

  Molecules mixed with air and saliva
• How do gustation and olfaction complement each other?

  They enhance interpretation of food and smell
• What is the primary special sense in animals?

  Olfaction (smell)
• How does the sensitivity of animal olfaction compare to humans?

  Animals have a far more sensitive sense of smell
• What induces the sensation of gustation?

  Binding of chemical molecules with receptors
• What are the main components of the olfactory system?

  Olfactory bulb, tract, gyrus, and lobe
• Why is olfaction essential for animals?

  It helps locate food and detect danger
• Where are olfactory cells found?

  On the ethmo-turbinate bones of the nasal cavity
• What do olfactory cells give rise to?

  Olfactory nerve fibers that terminate in the bulb
• What type of neurons are found in the olfactory mucosa?

  Bipolar neurons
• What is the function of the olfactory knob?

  It gives rise to 10-20 cilia
• What must odorant molecules do to stimulate olfactory cells?

  Enter mucus and bond with binding protein
• What is the role of the olfactory-binding protein?

  To carry or concentrate odorant molecules
• What emerges at the opposite end of the sensory neuron?

  A single nonmyelinated axon
• How do the axons of olfactory neurons differ from other cranial nerves?

  They form small fascicles called fila olfactoria
• Where do the fascicles of axons pass through?

  Foramina in the cribriform plate
• What happens to the axons in the olfactory bulb?

  They synapse with tufted and mitral cells
• What do taste buds contain?

  Taste receptor cells
• Where are taste receptor cells located in dogs?

  In various types of papillae on the tongue
• What types of papillae contain taste buds in dogs?

  Fungiform, vallate, and foliate
• Where are fungiform papillae primarily located?

  Throughout the rostral two-thirds of the tongue
• Where do vallate papillae occupy on the tongue?

  Caudal portion of the dorsal tongue
• Where are foliate papillae found?

  Dorsolateral part of the caudal tongue
• How many taste buds do dogs have?

  About 1700
• How many taste buds do humans have?

  About 9000
• How many taste buds do cats have?

  About 470
• What are the locations of different taste sensations on the tongue?

  1. Meaty taste - rostral two-thirds of the tongue
  2. Sweet taste - rostral and lateral portions
  3. Salty and sour taste - lateral sides, caudal to sweet
  4. Bitter taste - caudal portion of the tongue