The nose is an integral part of respiration and olfactory sensation. Both roles include varying components and techniques that work effectively and efficiently.
The nose is a cartilaginous organ on the face responsible for inhalation and exhalation of air and processing of scents and smells. Air is inhaled through the nose, and nose hairs catch the larger particles of dust and debris. Cilia and mucous in the nasal passages humidify, warm the air and catch any remaining foreign bodies before the inhaled air is passed down through the pharynx, larynx and trachea into the lungs.
Smells are processed simultaneously with respiration as the inhaled air passes over chemoreceptors, otherwise known as the olfactory epithelium. Soluble molecules are absorbed by the chemoreceptors, while proteins collect the non-soluble molecules and transport them to the chemoreceptors. All of this information is transported by axons in the olfactory nerve to the olfactory bulb. The olfactory bulb is responsible for conveying messages to the brain to organize and understand the scents inhaled.
Once all of this has occurred, the lungs exhale the left over air out through the nose to complete the cycle. In this manner, the nose is responsible for both inhalation and exhalation.