Nose

Nose anatomy includes the external bridge shaped by bone and cartilage and the internal nasal cavity divided by a septum. As air enters the nostrils, it swirls over ridges called turbinates that slow the flow and maximize contact with mucous membranes. This process warms cold air, humidifies dry air, and traps dust or microbes in sticky mucus.

Tiny hairs near the nostrils catch larger particles, while cilia farther back sweep mucus toward the throat to be swallowed. Blood vessels just beneath the lining help regulate temperature, explaining why the nose turns red in chilly weather. The sinuses—air-filled spaces in surrounding bones—lighten the skull and act as resonance chambers for the voice.

The upper portion of the nasal cavity houses the olfactory epithelium, a patch of sensory neurons with receptor proteins tuned to specific molecules. When odor molecules dissolve in the mucus, they bind to these receptors and trigger electrical signals that travel through the olfactory nerve into the brain's limbic system. This direct connection explains why smells can evoke strong memories and emotions instantly.

The nose also influences taste and overall respiratory health. When a cold or allergies swell the nasal lining, airflow decreases and smell perception drops, making foods seem bland. Healthy nasal passages filter pollutants before air reaches the lungs, while breathing through the nose encourages diaphragmatic respiration and efficient oxygen exchange.

Caring for the nose includes staying hydrated, avoiding tobacco smoke, and using protective gear in dusty workplaces. Saline rinses can relieve congestion by thinning mucus, and allergy management keeps tissues from inflaming chronically. Researchers explore electronic noses for detecting hazards, as well as regenerative therapies to restore smell after injury or infection.