Taste and Smell

Taste and Smell

∙ Both senses use chemoreceptors

∙Stimulated by chemicals in solution

• mouth = saliva

• nose = mucous

∙ Both senses complement each other and respond to many of the same stimuli

Olfaction - the sense of smell

Olfactory receptors are in the roof of the nasal

cavity

∙Are Neurons with long cilia (olfactory hair)

∙ Chemicals must be dissolved in mucus for

detection

Olfaction and the brain

Impulses are transmitted via the olfactory nerve (cranial

nerve I)

∙ Interpretation of smells is made in the cortex (olfactory

area of temporal lobe)

The Tongue and Taste

• ∙ The tongue is covered with projections called papillae

• ∙ Filiform papillae – sharp with no taste buds

  • papillae sometimes contains taste buds but trap bacteria and food dye particles

  • grips onto utensils or cups when eating/drinking

• ∙ Fungiform papillae – central-dorsal with taste buds

• ∙ Circumvallate papillae – large papillae with taste buds (in back of tongue)

• ∙ Foliate- small, clustered, each side of the tongue with taste buds

Black hairy tongue

happens if no hygiene

Gustation - the sense of taste

• ∙ Location of taste buds

• ∙Most are on the tongue

• ∙Soft palate

• ∙Cheeks

• ∙Taste buds house the receptor organs

Histology of Tongue

Burning tongues

• Does burning your tongue actually kill tastebuds?

  • yes, but every 8-10 days, tastebuds are recreated through mitosisZ

Structure of Taste Buds

∙ Gustatory cells are the chemoreceptors

∙ Have gustatory hairs (long microvilli)

∙Hairs are stimulated by chemicals dissolved in saliva

∙ Impulses are carried to the gustatory complex (parietal lobe) by several cranial nerves because taste buds are found in different areas

Taste Sensations

• ∙ Sweet receptors

  • ∙Sugars

  • ∙Saccharine

  • ∙Some amino acids

• ∙ Sour receptors

  • ∙Acids

• ∙ Bitter receptors

  • ∙Alkaloids

• ∙ Salty receptors

  • ∙ Metal ions

• ∙ Umami (MSG)

  • ∙ glutamic or aspartic acid