A cat's nose is an organ or organ system. By definition, organs are made up of two or more tissues. So what is a tissue? By definition, a tissue is made up of many similar cells. You know what a cell is. They occur in various types with various functions, such as the mucous-producing ciliated cells that trap dust and germs along the airway. On the outside there are also specialized skin cells that are sometimes a little wet, like a dog's nose. Of course there are other tissues, such as the cartilage that gives the nose its internal bracing, other bracing cartilages that keep the airway open, the sinus cavities, and (really important) those nerve cells that detect scent and transmit that information to the brain.

Cat Noses: Inside the cat's nose, separated by a nasal septum, is a labyrinth of bony platelike projections called the conchae. The conchae nearly fill the interior of the nose. They are covered by an olfactory mucosa, providing a surface of around 3-6 square inches. This size is twice the amount in a human's nose. In the mucosa are olfactory cells that detect scents. The olfactory cells are only at the top back of the nasal cavity, so the scents only reach the cells if the cat is sniffing (rather than just breathing). Below the nasal cavity are also curved cartilage tubes. These tubes are called the vomeronasal organ, or Jacobson's organ. These tubes connect to small holes behind the upper incisor teeth. This arrangement allows the cat to "taste scent" by opening its mouth and allowing the scent to penetrate through the tubes. When a cat does this, it looks like it is grimacing, and it also seems to be in a trancelike state. This activity is called the "Flehmen response". In human's the Jacobson's organ is only rudimentary, so we can't process scent information the same way cats can. Source: Understanding Cats -- Their History, Nature and Behavior, by Roger Tabor, The Reader's Digest Association, Inc., Pleasantville, NY, 1995, pp. 64-65.