Human Nose

The human nose as an organ performs many functions aside from just being a conduit to the respiratory and olfactory systems. Within a split second, it modifies the moisture of inhaled air to a constant relative humidity of 75%, and the temperature to a constant of 98.6°F, irrespective of the temperature (winter or summer) outside. It’s the first line of defense for inhaled foreign particles - large particles are captured by hairs and smaller ones get caught in mucus.

The shape of the nose also changes vocal resonance and affects your voice. The nose also helps to keep water out of the body. We can't close our nose, but its shape, position, size of the nostrils, and nostril hairs themselves (which are hydrophobic), all serve to block water from entering the nasal passages.