1.6D Smell, Taste, Touch, & Pain

Olfactory System (Olfaction)

Sensory system detecting airborne chemical molecules through nasal epithelium receptors; uniquely bypasses thalamus, sending signals directly to limbic system triggering emotional memories.

Thalamus

Central relay station routing sensory information to cortex for all senses except smell; transmits touch and pain signals to somatosensory cortex.

Pheromones

Airborne chemical signals released by individuals affecting behavior or physiology of same species members; detected through specialized olfactory receptors for communication.

Gustation

Chemical sense detecting dissolved food molecules through lingual taste buds; five basic categories include sweet, salty, sour, bitter, umami sensations.

Taste Receptors

Specialized chemoreceptor cells within taste buds on tongue papillae; detect dissolved chemicals in saliva, transmitting signals via gustatory pathway to brain.

Umami

Fifth basic savory taste signaling protein-rich foods; detected by glutamate receptors, commonly experienced with meat, cheese, and monosodium glutamate.

Oleogustus

Sixth basic taste category for fatty acids distinct from other tastes; detected by specialized receptors influencing food preferences and nutritional intake.

Medium Tasters

Individuals with moderate taste bud density representing majority of population; experience average sensitivity to flavors including bitterness between supertasters and nontasters.

Nontasters

Individuals with fewer than average taste buds causing reduced flavor sensitivity; particularly less responsive to bitter compounds like phenylthiocarbamide compared to supertasters.

Gate Control Theory

Spinal cord mechanism where large nerve fibers carrying touch can close neurological gate blocking small fiber pain signals; explains why rubbing injuries reduces pain.

Phantom Limb Sensation

Experiencing tactile sensations or pain in amputated body parts; occurs because brain's somatosensory cortex map retains representation despite physical limb absence.