They can improve the sense of smell by increasing the area available to absorb airborne chemicals, and they can warm and moisten inhaled air, and extract heat and moisture from exhaled air to prevent desiccation of the lungs. Olfactory turbinates are found in all living tetrapods, and respiratory turbinates are found in most mammals and birds. Animals with respiratory turbinates can breathe faster without drying out their lungs, and consequently can have a faster metabolism. For example, when the emu exhales, its nasal turbinates condense moisture from the air and absorbs it for reuse. Dogs and other canids possess well-developed nasal turbinates. These turbinates allow for heat exchange between small arteries and veins on their maxilloturbinate (turbinates positioned on maxilla bone) surfaces in a counter-current heat-exchange system. Dogs are capable of prolonged chases, in contrast to the ambush predation of cats, and these complex turbinates play an important role in enabling this (cats only possess a much smaller and less-developed set of nasal turbinates). This same complex turbinate structure help conserve water in arid environments. The water conservation and thermoregulatory capabilities of these well-developed turbinates in dogs may have been crucial adaptations that allowed dogs (including both domestic dogs and their wild prehistoric gray wolf ancestors) to survive in the harsh Arctic environment and other cold areas of northern Eurasia and North America, which are both very dry and very cold.Reptiles and more primitive synapsids have olfactory turbinates that are involved in sensing smell rather than preventing desiccation.
Each pair is composed of one concha in either side of the nasal cavity, divided by the septum.The superior conchae are smaller structures, connected to the middle conchae by nerve-endings, and serve to protect the olfactory bulb. The openings to the posterior ethmoidal sinuses exist under the superior meatus.The middle conchae are smaller. In humans, they are usually as long as the little finger. They project downwards over the openings of the maxillary and anterior and middle ethmoid sinuses, and act as buffers to protect the sinuses from coming in direct contact with pressurized nasal airflow. Most inhaled airflow travels between the inferior concha and the middle meatus.The inferior conchae are the largest, and can be as long as the index finger in humans, and are responsible for the majority of airflow direction, humidification, heating, and filtering of air inhaled through the nose.The inferior conchae are graded 1–4 based on the inferior concha classification system (known as the inferior turbinate classification system) in which the total amount of the airway space that the inferior concha takes up is estimated. Grade 1 is 0–25% of the airway, grade 2 is 26–50% of the airway, grade 3 is 51–75% of the airway and grade 4 is 76–100% of the airway.There is sometimes a pair of supreme conchae superior to the superior conchae. When present, these usually take the form of a small crest. Function
The conchae comprise most of the mucosal tissue of the nose and are required for functional respiration.