Midterm Discussions and Taste Lectures


  • Chemical Senses Lecture Overview

    • This segment shifts to discussing chemical senses, particularly taste.

    • Taste is distinct from olfaction and has its own processing pathway.

  • Taste Bud Anatomy

    • Overview of taste buds, focusing on gustatory cells.

    • Explanation of cell replacement due to environmental exposure.

    • Gustatory cells release neurotransmitters but do not fire action potentials directly.

    • Description of the signal pathway leading from taste cells to the brain.

  • Taste Pathway Basics

    • Taste signal travels through the brainstem to the thalamus and gustatory cortex.

    • Taste texture processed separately through somatosensory cortex.

  • Functions of Taste

    • Two main functions: identification of nutritious food and toxicity assessment.

    • The importance of bitter tasting as a cue for potential toxins is highlighted.

  • Overview of Tastes

    • Five primary tastes: sour, umami, sweet, salty, and bitter.

    • Taste sensation is mediated through distinct receptors, specifically G-protein coupled receptors (GPCRs).

  • Neuroanatomy of Taste

    • Detailed description of how taste processing begins in the tongue and involves sensory neurons and ganglia.

    • Key structures in the taste signal pathway identified, including various ganglia involved.

  • Taste Taste Buds and their Distribution

    • Explanation that taste buds are not uniformly distributed on the tongue.

    • Note regarding individual tastes and their receptor specificity.

  • Molecular Transduction of Taste

    • Discussion of specific taste receptors and their physiological functions (i.e. sour - protons, salt - sodium).

    • Importance of identifying receptor channels and their role in transduction.

  • Bitter Taste Complexity

    • Explanation of the large variety of bitter compounds.

    • Identification of GPCRs activated by bitter substances, indicating evolutionary significance.

  • Sweet Taste and Its Mechanisms

    • Discussion of sweet receptors, including GPCRs and their binding properties with sugars.

    • Mention of artificial sweeteners like aspartame and their peculiarities in binding the sweet receptor despite being dipeptides.

  • Umami Taste

    • Detailed exploration of umami, glutamate as a key component found in savory foods.

    • Description of receptors responsible for umami sensation and cultural significance.

  • Spicy Taste and Capsaicin

    • Explanation of capsaicin and its role in spicy foods (affect on temperature receptors).

    • Distinction between heat sensation and taste using capsaicin as a research tool.

  • TRP Channels and Temperature Sensation

    • Overview of TRP channels that mediate both capsaicin sensitivity and temperature perception.

    • Discussion surrounding the evolutionary significance of these receptors in taste and temperature interaction.

  • General Insight into Flavor

    • Understanding flavor as a subjective experience, integrating taste, smell, and texture.

    • Implications of flavor perception on dietary choices and sensory experience.

  • Closing Remarks

    • Encouragement for students to submit their homework and wrap-up lecture details.

  • Notes on Assessments

    • Review deadlines and policies, emphasizing submission of homework regardless of delays.