The Sense of Smell

Importance of Smell

• Animal Superiority: Dogs detect odors at concentrations $100$ times lower than humans, assisting in navigation, identification, and detection.
• Human Uses:
  • Food Safety: Distinguishing fresh from rotten food and avoiding previous illness-causing foods.
  • Tracking: Locating sources of gas leaks, fires, or desirable aromas.
  • Chemosignaling: Bodily odors may communicate information, though less studied in humans.
  • Enrichment: Adds richness to existence; its loss (e.g., with COVID-19) highlights its significance.

Olfactory Equipment

• Active Organ: The nose is an active instrument; sniffing maximizes odor detection.
• Olfactory Epithelium: Lines the roof of the nasal cavity, containing receptor cells for smell.
• Receptor Cells: Covered with minute, hair-like antennae that project through mucus to contact air containing odorants.