Physiology of taste how chemical signals are generated and taste perception created

1. Special Senses : Taste
Dr Zaid Azhar

2. Taste
• Gustation: Sensation of
taste.
• Taste Bud: Epithelial cell
receptors clustered in
barrel-shaped taste buds.
• Taste buds depolarize
upon stimulation and if
reach threshold, release
neurotransmitters that
stimulate sensory
neurons.

3. Taste
• Each taste bud contains taste cells responsive to each of the
different taste categories.
• A given sensory neuron may be stimulated by more than 1
taste cell in a number of different taste buds.
• One sensory fiber may not transmit information specific for
only 1 category of taste.
• Brain interprets the pattern of stimulation with the sense of
smell; so that we perceive the complex tastes.

4. Distribution of taste receptors
• 5 basic modalities of
taste.
• Salt: Na+ passes through
channels and activates
specific receptor cells,
depolarizing the cells.
• Sour: Presence of H+.
• Sweet and bitter:
Mediated by receptors
coupled to G-protein
• Umami: pleasant,
savoury taste, glutamate
receptor

5. Receptor Potential

6. Taste nerves
• Anterior 2/3rd of
tongue: CN VII Facial –
chorda tympani
• Posterior 1/3rd of
tongue: CN IX
Glossopharyngeal

7. Central taste pathway

8. Clinicals
• Complete loss – aguesia
• Partial loss – hypoguesia
• Distortions of taste – dysguesia