Taste & Smell

• What is the importance of taste sensation?

  Drives appetite and protects from poisons
• What are the five basic taste sensations?

  • Salty
  • Bitter
  • Sweet
  • Sour
  • Umami
• What compounds stimulate the salty taste sensation?

  NaCl and mineral salts like Mg, K
• Which compounds are associated with the bitter taste sensation?

  Many organic compounds like caffeine
• What types of substances are associated with the sweet taste sensation?

  Sugars, fructose, glucose, lactose
• What does umami mean in Japanese?

  Delicious taste, savory or meaty
• How do sensory nerve fibers from taste buds reach the brainstem?

  They travel by three different nerves
• Which cranial nerve carries information from the anterior 2/3rd of the tongue?

  The facial nerve (cranial nerve VII)
• Which cranial nerve carries information from the posterior 1/3rd of the tongue?

  The glossopharyngeal nerve (cranial nerve IX)
• What is the innervation for taste buds in the pharynx, epiglottis, and palate?

  Vagus nerve (CN X)
• How many fungiform papillae does a person have approximately?

  ~195 fungiform papillae
• How many taste buds are found on each fungiform papilla?

  3-5 taste buds
• How many circumvallate papillae does a person have approximately?

  7-12 circumvallate papillae
• How many taste buds are on each circumvallate papilla?

  More than 100 taste buds
• What is the arrangement of circumvallate papillae on the tongue?

  Arranged in a circular row before sulcus terminalis
• What is the innervation for circumvallate papillae?

  Cranial nerve IX
• What is the shape of the taste buds located along the sides of the tongue?

  Leaf-shaped taste buds
• What is the role of supporting cells in taste buds?

  Support and maintain gustatory receptor cells
• What is the function of basal cells in taste buds?

  Replace old and damaged gustatory receptor cells
• What are Type I cells in taste buds responsible for?

  Provide structural support and maintain ionic balance
• What do Type II cells in taste buds detect?

  Sweet, bitter, and umami tastes
• What do Type III cells in taste buds detect?

  Sour tastes
• How is information relayed from taste receptor cells?

  By neurotransmitter to sensory fiber terminals
• Where do primary gustatory fibers synapse?

  In the solitary tract nucleus of medulla oblongata
• What is the role of the cerebral cortex in taste perception?

  Conscious perception or identification of taste
• Which part of the brain is involved in emotional tastes and memory function?

  Limbic system (hippocampus, hypothalamus, amygdala)
• What does the glossopharyngeal nerve (IX) supply?

  Touch and taste to the posterior 1/3 of the tongue
• What does the vagus nerve (X) innervate?

  Taste buds in the larynx
• What does the facial nerve (VII) supply?

  Taste to the anterior 2/3 of the tongue
• What does the trigeminal nerve (V) supply?

  Sensation to the anterior 2/3 of the tongue
• What is the overall mechanism of taste transduction?

  1. Taste stimuli activate receptors
  2. Signal transduction occurs
  3. Neurotransmitters are released
  4. Signals sent to the brain
• What receptors are involved in spiciness and pain sensation?

  TRPV1 receptors in the tongue epithelium
• What activates TRPV1 receptors?

  Heat, capsaicin, and acid
• What happens to taste sensation as people age?

  Number of taste buds decreases and shrinks
• What can speed up the loss of taste and smell?

  Diseases, smoking, and harmful particles
• What are common sensory disorders related to taste?

  • Hypogeusia: Diminished taste sensation
  • Ageusia: Loss of taste sensation
  • Dysgeusia: Disturbed taste sensation
  • Taste blindness: PTC tasteless to some
  • Phantom taste perception: Lingering unpleasant taste
• What are common sensory disorders related to smell?

  • Hyposmia: Reduced ability to detect odors
  • Anosmia: Inability to detect odors
  • Dysosmia: Distorted sense of smell
• Where are taste buds distributed in the oral cavity?

  • Tongue papillae
  • Palate
  • Pharynx
  • Laryngeal epiglottis
  • Entrance of the oesophagus
• What is the size of taste buds?

  Ovoid bodies measuring 50-70μm
• What types of cells make up taste buds?

  Supporting cells, basal cells, gustatory cells